# How to Compare Ducted, Ductless, and Mixed Heat Pumps Before a New-Home Design Freeze

Source: https://brictale.com/build/materials/compare-new-home-ducted-ductless-mixed-heat-pump-systems-before-design-freeze
Published: 2026-09-28
Audience: Homeowner
Published by Brictale, a consumer home-intelligence publication. https://brictale.com

## Short answer

Carry the architecture that satisfies every room load and comfort requirement while leaving a coordinated route for ducts or line sets, ventilation, condensate, electrical work, service access, and future rooms. Compare all three options on one load report and floor plan. Before freezing the design, have the HVAC designer verify OEM performance and matching, the electrician verify the load schedule, and the team record permits, responsibilities, and commissioning evidence for your actual state and local authorities.

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# How to Compare Ducted, Ductless, and Mixed Heat Pumps Before a New-Home Design Freeze

Carry the architecture that satisfies every room load and comfort requirement while leaving a coordinated route for ducts or line sets, ventilation, condensate, electrical work, service access, and future rooms. Compare all three options on one load report and floor plan. Before freezing the design, have the HVAC designer verify OEM performance and matching, the electrician verify the load schedule, and the team record permits, responsibilities, and commissioning evidence for your actual state and local authorities.

This guide is for a United States homeowner at schematic design or before design freeze. It does not size equipment, interpret a project’s code, approve a refrigerant installation, or replace a licensed HVAC designer, electrician, architect, energy rater, or the authority having jurisdiction (AHJ). No project location was supplied, so no city-, county-, or state-specific rule is asserted here. Record the actual state, county, municipality, or other permitting authority for the home before relying on any local requirement.

For other published homeowner decisions, browse the [Brictale homeowner blog](/blog).

## The decision is a system architecture choice, not a unit brand choice

Choose the architecture that can be proven against the room-by-room loads, comfort brief, routes, ventilation plan, electrical schedule, service access, and warranty conditions on the same house plans. A ducted system distributes conditioned air through a central air handler and ducts; a ductless system places indoor units in the rooms or zones; a mixed system combines those distribution methods. The right answer is the one whose complete project scope still works after every trade has drawn its part.

### The three architectures in plain language

In a ducted architecture, one or more outdoor units connect to an indoor air handler. The air handler sends supply air through ducts to registers and receives return air through a return path. The equipment may be in a basement, closet, conditioned attic, crawlspace, or another location allowed by the design and the applicable installation instructions. One central system can make the house visually quiet, provide a single filtration point, and distribute air to rooms that are not open to one another. Its price is spatial: the home must reserve room for the air handler, supply ducts, returns, chases, bulkheads, grilles, access panels, and condensate management.

In a ductless architecture, each indoor unit conditions the space directly. The outdoor unit connects to one or more indoor units with refrigerant piping, control wiring, and a condensate arrangement. Indoor units can be high-wall units, floor consoles, or concealed or ceiling-mounted units, depending on the product family. PNNL’s Building America guidance identifies the availability of duct and air-handler space, the conditioned area, zoning, ventilation, dehumidification, low-temperature capacity, filtration, and noise as comparison inputs; it also says the homeowner and designer should calculate loads, locate units, assess electrical requirements, and commission the system. [PNNL’s ductless heat-pump guidance](https://basc.pnnl.gov/resource-guides/ductless-mini-split-heat-pumps) is useful here because it describes a process, not just a product category.

In a mixed architecture, some rooms or zones are served by a ducted air handler and others by ductless indoor units. A concealed short-duct air handler may serve several nearby bedrooms while wall or ceiling units serve a great room and an addition. Another mixed arrangement may use a central ducted system for most rooms and an independent ductless zone for a room with a different schedule or a route that cannot be reached economically. “Mixed” is not a performance guarantee. It is a coordination decision with more than one distribution method, more model combinations, and more opportunities for mismatched controls or unclear ownership.

![Ducted, ductless and mixed heat-pump routes compared across rooms, equipment and handoffs](https://brictale.com/images/home/build/materials/compare-new-home-ducted-ductless-mixed-heat-pump-systems-before-design-freeze/architecture-route-comparison.webp)

### Why the unit-first shortcut fails

The same nominal capacity can behave differently when it is connected to a different indoor unit, operated at a different outdoor temperature, installed with a different line-set length, or asked to serve several rooms through one outdoor unit. A total floor-area estimate also hides room exposure, window area, internal gains, ceiling height, air leakage, envelope assemblies, and the effect of doors being closed. ENERGY STAR tells homeowners to use the actual characteristics of the home instead of a rule of thumb and to confirm that airflow meets the manufacturer’s performance specifications. [Read the ENERGY STAR quality-installation guidance](https://www.energystar.gov/saveathome/heating-cooling/hvac-quality-installation).

An equipment brochure can also leave out what the construction team must build. A ductless proposal may show six heads but omit the condensate pumps, branch box, line-set protection, wall backing, access panels, outdoor-unit stands, controls, and electrical circuits. A ducted proposal may show an air handler but omit return grilles, transfer paths, filters, supply plenums, duct insulation, balancing, and access to dampers. A mixed proposal may price the equipment correctly and still fail because nobody reserved the chase that connects the outdoor wall to the hidden indoor unit.

### What the homeowner is deciding

The homeowner owns the brief and the acceptance criteria. That means deciding, in writing:

- Which rooms need independent temperature schedules.
- Whether closed bedroom doors must remain comfortable without transfer grilles or open doors.
- Whether a quiet ceiling, a visible wall head, floor grilles, or service panels is acceptable.
- How important whole-home filtration, humidity control, and ventilation integration are.
- Whether future rooms, an unfinished basement, an accessory dwelling unit, or a later office should be reserved for.
- How much electrical capacity, outdoor equipment visibility, maintenance access, and first cost are acceptable.
- Which records must be delivered before the system is accepted.

The homeowner does not choose duct dimensions, wire sizes, refrigerant charge, structural supports, protective devices, or permit compliance from this guide. Those are professional design and installation tasks governed by the selected equipment documents and the project jurisdiction.

### Compact originality brief

Current answers from DOE, PNNL, ENERGY STAR, and manufacturer pages explain heat pumps, ductless systems, quality installation, or product families. They rarely join the floor plan, room loads, zone boundaries, routes, ventilation, condensate, electrical service, bid scope, warranty limits, and commissioning record in one pre-freeze decision.

The missing decision is not “which heat pump is best?” It is “which distribution architecture can this exact new home carry forward without an unresolved handoff?” The original contribution in this article is the **New-home heat-pump architecture release worksheet**. It normalizes ducted, ductless, and mixed options against identical inputs, assigns responsibility, and creates a release gate.

You can check the contribution by asking another HVAC designer to fill the same fields from the same floor plan, then comparing whether the proposed equipment, routes, electrical schedule, ventilation plan, AHRI record where applicable, and commissioning record agree. The worksheet is a synthesis of the cited sources and planning practice, not collected field data, an engineering standard, or firsthand testing.

**Method:** Record one floor plan and one room-by-room load report, normalize each option into the same fields and units, score only stated homeowner priorities, then require OEM expanded-performance data, an AHRI match where applicable, coordinated plans, and commissioning evidence before design freeze.

**Limitations:** This is a planning and handoff tool, not equipment sizing, engineering, a permit document, a code interpretation, or a substitute for the licensed HVAC, electrical, design, inspection, and commissioning professionals responsible in the project jurisdiction.

### The release test

Do not freeze the architecture until you can answer yes to all of these questions:

1. Is there a room-by-room heating and cooling load report using the current envelope, windows, orientation, infiltration assumptions, occupancy assumptions, and design temperatures?
2. Does every occupied room have a deliberate delivery and return or transfer strategy?
3. Does the plan show every air handler, indoor unit, outdoor unit, duct, refrigerant line set, control, condensate route, filter, grille, access panel, and service path?
4. Does the proposed electrical schedule include the actual equipment and accessories, with the electrician’s design review still pending where required?
5. Is whole-home ventilation separate from, or intentionally integrated with, space conditioning and documented in the plan?
6. Can the HVAC professional produce the exact OEM performance tables and matching evidence for the proposed combination?
7. Does the bid identify who supplies and installs every connection between HVAC, electrical, framing, drywall, roofing, controls, and ventilation?
8. Is the acceptance record defined before installation, including measured airflow where ducts exist, refrigerant and electrical checks, control operation, condensate behavior, and owner documents?

If any answer is no, the next decision is not ducted versus ductless. It is which missing input or handoff must be resolved first.

## Freeze the inputs before anyone compares equipment

Before comparing equipment, freeze a common input sheet: current plans, envelope assumptions, room-by-room loads, design temperatures, room schedules, zone boundaries, ventilation and filtration goals, physical routes, electrical constraints, and future-room assumptions. Each architecture must be tested against the same inputs, or the comparison merely rewards the proposal with the least complete scope.

### Start with the plan set, not a catalog

Collect the current architectural plan set and mark the version and date. Include floor plans with dimensions, ceiling heights, window and door schedules, exterior wall assemblies, roof and attic condition, foundation or crawlspace condition, insulation assumptions, air-sealing target if one is specified, solar orientation, and the proposed mechanical spaces. Add furniture or use patterns where they affect supply-register placement, indoor-unit sightlines, or noise. Turn those use patterns into a separate room-by-room comfort brief before the HVAC comparison.

For each room, record area in square feet, ceiling height in feet, number and size of exterior windows, exterior wall length in feet, adjacent conditioned and unconditioned spaces, expected occupancy, door position during normal use, and special loads such as cooking, electronics, or equipment. These are homeowner inputs and design coordination inputs; the HVAC designer decides which are relevant to the load method.

Mark rooms that must remain comfortable with doors closed. A ductless indoor unit in a great room is not automatically a delivery method for a closed office or bedroom. PNNL notes that a ductless system does not necessarily place an indoor unit in every room and that rooms without a head can become uncomfortable; transfer fans and return paths are possible design responses, but they must be deliberately designed. [See PNNL’s discussion of air distribution and zoning](https://basc.pnnl.gov/resource-guides/ductless-mini-split-heat-pumps).

### Record loads in Btu/h, not only tons

Ask the HVAC designer for room-by-room design heating load and design cooling load in Btu/h, together with the outdoor design temperatures in °F, indoor design temperatures in °F, humidity assumptions, and the software or method used. Ask for the total only after the room values are visible. “Three tons” is a rounded equipment label; it is not a room distribution plan.

Use a table like this for the handoff. Leave blank values blank rather than filling them from floor area.

| Input | Unit | Homeowner or designer action | Ducted record | Ductless record | Mixed record |
|---|---:|---|---|---|---|
| Room heating load | Btu/h | Obtain from current room-by-room load report | Same rooms and assumptions | Same rooms and assumptions | Same rooms and assumptions |
| Room cooling load | Btu/h | Obtain from current room-by-room load report | Same rooms and assumptions | Same rooms and assumptions | Same rooms and assumptions |
| Outdoor heating design temperature | °F | Confirm location and source with HVAC designer | Record value and source | Record value and source | Record value and source |
| Outdoor cooling design temperature | °F | Confirm location and source with HVAC designer | Record value and source | Record value and source | Record value and source |
| Indoor unit or register count | count | Choose comfort and appearance priorities | Registers and returns | Heads, cassettes, or consoles | Both |
| Duct length | ft | Reserve routes on plan | Supply and return by section | 0 or short-duct lengths | Ducted portions |
| Refrigerant line-set length | ft | Measure drawn route, not a straight-line guess | Outdoor-to-air-handler route | Each outdoor-to-indoor route | Each route |
| Branches or branch-box connections | count | Ask designer to identify | If the OEM requires them | If the OEM requires them | If the OEM requires them |
| Electrical schedule | V, A, circuit | Electrician reviews exact data | Equipment and accessories | Each required circuit and accessory | Combined schedule |
| Ventilation airflow | cfm | HVAC or ventilation designer documents | Separate or integrated | Separate or integrated | Separate or integrated |
| Condensate route | ft, slope, lift | Show gravity path or pump | Air handler and ducts | Each indoor unit as applicable | Every applicable component |
| Service access | ft or access area | Architect reserves clear working space | Air handler, filter, dampers | Every head and outdoor unit | Both |

The entries do not size equipment. They prevent a proposal from being compared on a different set of assumptions.

![Common heat-pump comparison worksheet with room loads, routes, ventilation and electrical inputs](https://brictale.com/images/home/build/materials/compare-new-home-ducted-ductless-mixed-heat-pump-systems-before-design-freeze/common-inputs-worksheet.webp)

### Get the design temperatures and jurisdiction into the record

Write the project address, county, municipality, state, and the name of the permitting office or other AHJ. Then ask the HVAC designer and architect which adopted mechanical, electrical, energy, fire, and building requirements apply to that location and project type. Record the edition and any amendments they rely on. A rule from one city or state is not a national rule.

For this assignment, the actual project jurisdiction is unknown. Therefore, this guide does not tell you that a particular clearance, permit, disconnect, refrigerant rule, ventilation rate, or equipment location is legal everywhere. The actual AHJ may be a city building department, a county department, a state agency, or another named authority. Ask that authority or the responsible licensed professional before the plans are frozen, and preserve the written answer or permit checklist in the project record.

Federal refrigerant requirements are a different scope. In the United States, EPA Section 608 requires certification for technicians who maintain, service, repair, or dispose of equipment that could release refrigerant, including attaching gauges and adding or removing refrigerant. [Check the current EPA Section 608 requirements](https://www.epa.gov/section608/section-608-technician-certification-requirements). The homeowner can ask for credentials and records; the homeowner should not open a refrigerant circuit or direct an unqualified person to do so.

### Add the living brief that load reports cannot express

Two designs can have comparable calculated loads and feel very different. Ask each household member to rank these from 1, most important, to 5, least important: quiet operation, independent schedules, invisible equipment, strong filtration, humidity control, low outdoor-unit visibility, simple maintenance, resilience during a power interruption, and capacity for future rooms. The purpose is not to create a mathematically true comfort score. It is to expose conflicts before a contractor prices them.

Ask specific questions:

- Is a visible high-wall unit acceptable above the bed, sofa, or artwork?
- Will doors be closed at night, and if so, what delivery path serves those rooms?
- Is a single replaceable filter at an accessible air handler valuable to the household?
- Is there a room where dry air is already a problem or summer humidity is a known concern?
- Will the basement, attic, garage, workshop, or addition be finished later?
- Where can outdoor units be heard from bedrooms, patios, or property lines?
- Who will clean filters, and who will pay for deep cleaning or service access?

These are not equipment specifications. They are acceptance criteria that keep the decision from being hijacked by the lowest visible bid.

### Build a future-room and failure brief

List spaces that may be added within the next ten years. For each, record area in square feet, likely use, whether it is inside the current envelope, and whether the current electrical service, outdoor-unit location, mechanical room, chase, and condensate path could support it. Do not ask today’s equipment to serve an unmodeled future load. Instead, ask the designer whether the architecture should reserve space, a route, a panel position, a stub, or a separate future system.

Record what must happen if one indoor unit, one outdoor unit, one control, or one electrical circuit is unavailable. A single multi-zone outdoor unit can create a different failure dependency from several independent single-zone systems. A ducted system may have one central air handler and one filter location but also one central blower. A mixed system can preserve conditioning in some zones while adding more controls and service records. These are decision consequences, not universal performance claims.

### The first homeowner handoff

Give the architect and HVAC designer one dated folder containing the plan set, room schedule, comfort brief, future-room list, project address, jurisdiction record, and the worksheet. Ask the HVAC designer to return a marked-up plan that shows the assumptions they used. If the load report changes after windows, insulation, ceiling heights, or room uses change, restart the comparison. Do not let an old load report silently survive a major plan revision.

The next decision is whether the three architectures can be compared fairly. If one proposal lacks room loads, routes, or ventilation scope, request the missing design work before requesting a price.

## Compare ducted, ductless, and mixed architectures on the same plan

Compare ducted, ductless, and mixed systems by the same nine lenses: room coverage, zoning, air movement, duct or line-set routes, ventilation and filtration, humidity, electrical scope, service access, and future flexibility. A matrix is useful only when every cell names an input, an owner, and a verification record.

### Lens 1: room coverage and zone boundaries

Draw a circle or boundary around every proposed zone and list the rooms inside it. For a ducted system, list each supply terminal, return or transfer path, and the design airflow assigned to the room. For a ductless system, list each indoor unit and the rooms it is expected to condition. For mixed systems, identify exactly where the handoff between systems occurs.

A zone is not simply a thermostat name. It is the area whose load, airflow, temperature sensing, control behavior, and door conditions are designed together. If a bedroom depends on air moving from a hall, state whether the door is expected to remain open, whether a transfer path is designed, and how sound and smoke-control concerns are addressed by the professionals. If the room is intended to be independent, give it an appropriate delivery method.

For ductless systems, PNNL notes that it may not make sense to place an indoor unit in every room and that rooms without heads may become uncomfortable. That makes the room coverage drawing a critical design record, not a cosmetic layout. [Use the PNNL resource to frame the zoning question](https://basc.pnnl.gov/resource-guides/ductless-mini-split-heat-pumps).

Failure case: the contractor sizes a living-room head to cover an adjacent hallway and two bedrooms because the doors are open during a site visit. The homeowner later closes the bedroom doors at night. The load calculation may have been correct for the living room, but the architecture was never correct for the occupied pattern. The safe next step is to return to the HVAC designer with the actual door and schedule assumptions, not to add a random head after finishes are complete.

### Lens 2: ducts, line sets, and the building envelope

For ducts, mark the route, cross section, insulation or enclosure condition, access points, penetrations, and whether each segment lies inside or outside the thermal boundary. PNNL explains that ducts or air handlers in unconditioned areas can lose heating and cooling through leakage and conduction, while locating them within the thermal boundary changes how those losses affect the home. [Read PNNL’s duct-location discussion](https://basc.pnnl.gov/resource-guides/ductless-mini-split-heat-pumps).

Do not use PNNL’s discussion as a reason to eliminate all ducts. A well-coordinated ducted system inside the conditioned envelope may satisfy filtration, appearance, comfort, and closed-door room coverage better than a collection of visible heads. The relevant comparison is not “ducts always lose energy” against “ductless never loses energy.” The relevant comparison is the actual route, boundary condition, leakage control, air handler location, and model performance.

For refrigerant line sets, mark the actual drawn path in feet, each vertical rise, each penetration, bends, protection, insulation, supports, and the route to each indoor unit. The HVAC designer must check the exact OEM limits for length, elevation, pipe size, branch arrangements, charge adjustment, and allowable indoor-unit combinations. The homeowner’s measurement is a coordination input, not permission to install a line set.

Failure case: a floor plan shows a short straight line from an outdoor unit to a second-floor head, but the real route goes around a beam, through a closet, and up two stories. The extra length, access, wall repair, and condensate path appear only after framing. The safe next step is to have the architect and HVAC designer draw the three-dimensional route before the framing plan is issued.

DOE’s Building America work on a plug-and-play duct approach illustrates why distribution needs calculation and testing. That project used a calculation spreadsheet to select the number of ducts needed for each zone and evaluated a particular new-construction approach under stated enclosure assumptions; its example is not a universal duct diameter or layout rule. [Review the DOE duct-system evaluation](https://www.energy.gov/cmei/buildings/plug-and-play-duct-system-evaluation).

### Lens 3: filtration, ventilation, and humidity

Treat filtration and ventilation as separate questions. Space-conditioning equipment recirculates indoor air; whole-home ventilation brings outdoor air into the home and exhausts or transfers indoor air according to the design. A heat pump does not automatically solve the home’s outdoor-air requirement, range-hood exhaust, bathroom exhaust, radon strategy, or pressure balance.

For each architecture, document the ventilation equipment, outdoor-air intake, exhaust, controls, filtration location, filter dimensions, access, noise, condensate, and interaction with heating and cooling. Ask whether the ventilation system is independent, connected to a ducted air handler, connected through an energy-recovery ventilator, or handled by another named design. Do not assume that a ductless head can distribute fresh air to rooms it does not serve. If an HRV or ERV is being considered, keep its proposal and verification record separate from the heat-pump architecture decision so the two scopes cannot disappear into one allowance.

DOE’s field study of 51 recently built homes in Florida, Georgia, and South Carolina measured ventilation equipment, airflow, and leakage and found that most homes in the study did not meet ASHRAE 62.2 requirements; the study is regional and measured, not a national code declaration. [Read the DOE ventilation study and its stated scope](https://www.energy.gov/cmei/buildings/ventilation-and-indoor-air-quality-recently-constructed-us-homes-measured-data). Use it to justify a ventilation handoff and verification record, not to copy a rate into a different jurisdiction.

PNNL describes general trends in which ductless systems may have poorer dehumidification or less filtration than some ducted systems, but it explicitly cautions that these characteristics are not inherent to every technology and that individual models must be compared. [Compare the exact model data through the PNNL guidance and OEM documents](https://basc.pnnl.gov/resource-guides/ductless-mini-split-heat-pumps). For a humid climate, ask the designer to show how sensible and latent loads, ventilation moisture, control setpoints, and any separate dehumidification are addressed.

Failure case: the homeowner specifies “high filtration” and the bid includes a small accessory filter on a wall head. [PNNL’s supplemental-filter example](https://basc.pnnl.gov/resource-guides/ductless-mini-split-heat-pumps) warns that some supplemental ductless filters cover only a small part of the airflow path, allowing much air to bypass the added filter. The next step is to request the exact filter location, rated performance, pressure impact, replacement cost, and maintenance method for the model—not to treat the word “filter” as proof of whole-home particle control.

### Lens 4: electrical schedule and controls

List every outdoor unit, indoor unit, air handler, branch box, crankcase or auxiliary heater if proposed, ventilation fan, condensate pump, control transformer, disconnect, service receptacle if required by the design, and accessory. Record manufacturer name, exact model, voltage, minimum circuit information, maximum overcurrent information, phase, and quantity from the current OEM data. The electrician then reviews the schedule against the service, panel, feeder, branch-circuit layout, and local requirements for the project jurisdiction. Keep this equipment schedule as a named electrical handoff, with the electrician’s review status and unresolved service questions visible before rough-in.

Do not compare “one system” with “three systems” as if the count alone determines electrical burden. A ductless system may have several small indoor units but few branch circuits; a ducted system may include a larger air handler or auxiliary heat; a mixed system may have both. The exact data and the electrician’s load calculation control.

PNNL notes that some single-zone ductless systems on the market use 115/120 V and modest current on certain sizes, but it also describes that as an available market configuration, not a universal rule. [Treat PNNL’s electrical discussion as a prompt to check the exact model](https://basc.pnnl.gov/resource-guides/ductless-mini-split-heat-pumps). Never infer a circuit size from a product category or an online comment.

Controls need the same discipline. Record thermostat or remote type, wired or wireless sensors, temperature-sensing location, outdoor reset or staging behavior if applicable, ventilation interlock, vacation mode, heat/cool changeover, low-temperature behavior, and what happens when communication is lost. Ask who supplies each control and who programs it. In a mixed system, define whether systems share a schedule, operate independently, or are prevented from fighting each other.

Failure case: the HVAC proposal includes a brand-specific controller while the electrical bid includes only a general thermostat wire. The plans do not show the control interface between a ducted air handler, a ductless head, and the ventilation unit. The next step is a controls submittal reviewed by HVAC, electrical, ventilation, and the architect before ordering equipment.

### Lens 5: condensate, access, and water damage prevention

Every component that can produce condensate needs a named route, termination, slope or pump, overflow strategy, access, and responsible installer. Mark the air handler drain pan, secondary protection where the designer requires it, each indoor-unit drain, pump if gravity is unavailable, cleanout or service access, and the final discharge location. The homeowner can inspect whether the route appears on the plan. A qualified professional must select and install the system to the OEM instructions and applicable requirements.

The architecture with fewer visible ducts can still have more small condensate decisions. A high-wall head may need a short gravity drain; a concealed unit above a ceiling may need an access panel and a pump; a mixed system may have all of those plus a central drain. The comparison is the total route and maintenance burden, not the number of refrigerant pipes.

Failure case: a concealed indoor unit is placed above a finished ceiling with no access, the drain slopes toward a beam, and the pump is hidden behind drywall. The project has saved visible equipment space but created a future water-damage and service-access problem. The next decision is whether to move the unit, redesign the drain, add access, or choose a different indoor-unit type before closing the ceiling.

### Lens 6: noise, appearance, and serviceability

Walk the plan as an occupant and as a technician. Mark what will be visible from beds, desks, sofas, dining tables, porches, and property boundaries. Mark line-set covers, registers, grilles, bulkheads, access panels, outdoor-unit sightlines, and the sound path through walls or ceilings. Then ask the HVAC designer for the manufacturer’s sound data for the exact model and operating condition, rather than treating a family name as a measured room experience.

For serviceability, draw a box around each component showing the access path, working side, filter removal, coil and blower access, electrical disconnect location, line-set connections, drain, and replacement path. The architect owns the space reservation; the HVAC installer verifies that the planned access is practical; the builder keeps the access from being closed by framing or finishes.

Failure case: a head is visually acceptable in the rendering but conflicts with a curtain pocket, art rail, or cabinet; a ducted return is hidden behind a door swing; an outdoor unit is placed under a roof drip line or where snow and landscaping block service. The safe next step is a coordinated reflected-ceiling and elevation review, not an on-site improvisation after drywall.

### Lens 7: maintenance and ownership

Write a maintenance schedule before choosing the architecture. Include filter access and interval, outdoor-coil inspection, condensate checks, drain cleaning, control-battery or software needs if applicable, professional inspection, and deep cleaning of indoor units. PNNL says ductless mesh filters commonly need cleaning about every two weeks as a typical manufacturer recommendation and that wall-mounted units may need deeper cleaning depending on use and conditions. [Use PNNL’s maintenance guidance as a planning prompt](https://basc.pnnl.gov/resource-guides/ductless-mini-split-heat-pumps), then replace it with the exact OEM schedule.

The owner’s maintenance promise should be realistic. If a filter is above a stairwell, the design has assigned a fall and access problem to future occupants. If a ceiling cassette needs specialized cleaning, record who will do it and how the room will be protected. If a ducted filter is in a cramped attic, compare that access burden against a visible filter cabinet in a conditioned utility room. Maintenance is part of the architecture because the best design on paper can degrade if ordinary care is inaccessible.

The next decision is whether the three options can be normalized into a comparable scope and scored against the household’s priorities.

## Turn the preferred architecture into coordinated routes and responsibilities

The preferred architecture becomes real only when the homeowner, architect, HVAC designer, electrician, ventilation designer, builder, and AHJ each have a named handoff and a verification record. Put the responsibility map on the same revision-controlled sheet as the comparison so that “included” means the same thing to every bidder.

### Responsibility map

| Decision or record | Homeowner | Architect or designer | HVAC designer / contractor | Electrician | Builder | Ventilation professional | AHJ or inspector |
|---|---|---|---|---|---|---|---|
| Comfort priorities and appearance | Owns and approves | Translates into plan constraints | Tests feasibility | Notes control and circuit effects | Prices allowances | Notes IAQ interaction | Not a substitute for owner preference |
| Current floor plan and envelope | Supplies household changes | Owns drawing revision | Uses it for loads and routes | Uses it for equipment locations | Builds to it | Uses it for ventilation | Reviews submitted documents as required |
| Room-by-room loads | Reviews assumptions | Supplies geometry and assemblies | Calculates and signs scope | Uses design data | Flags field changes | Coordinates outdoor-air loads | Applies local review process where applicable |
| Indoor and outdoor locations | Approves visible locations | Reserves space and access | Selects practical locations | Checks equipment and disconnect needs | Protects locations during build | Coordinates intakes and exhaust | Checks only within its authority |
| Duct and line-set routes | Confirms priorities | Draws chases, backing, penetrations | Confirms OEM limits and installation | Coordinates crossings | Frames and seals openings | Coordinates ventilation routes | Reviews adopted requirements if applicable |
| Electrical schedule | States future loads | Coordinates panel location | Provides exact equipment data | Designs circuits and service | Installs or coordinates rough-in | Provides fan/control data | Applies state/local electrical process |
| Ventilation and filtration | States IAQ needs | Reserves routes and access | Coordinates controls | Coordinates power | Installs penetrations and backing | Designs and verifies ventilation | Applies actual adopted requirements |
| Condensate | Approves visible discharge constraints | Reserves access | Designs and installs drains/pumps | Powers pumps if needed | Provides structure and finish coordination | Coordinates if shared | Reviews only where authority applies |
| Bid inclusions | Compares scope | Explains design allowances | Prices equipment and labor | Prices electrical work | Prices framing/finish impacts | Prices ventilation | Not a bidder or design substitute |
| Commissioning record | Accepts evidence | Confirms plan-to-field match | Measures and documents system | Documents electrical checks | Closes access and finishes | Measures ventilation | Performs required inspection under local process |
| Handover | Receives manuals, warranties, schedules | Archives plans | Demonstrates operation | Delivers electrical documentation | Delivers closeout | Delivers ventilation record | Delivers permit or inspection records when applicable |

The map is a coordination tool, not a legal assignment of liability. Contracts, state licensing rules, local permits, and the actual scope of each professional control the project.

### What each handoff must contain

The homeowner-to-architect handoff contains the room list, furniture and door expectations, visible-equipment preferences, future rooms, project address, and jurisdiction record. The architect returns a plan with mechanical spaces, chases, ceiling zones, backing, penetrations, access panels, and finish constraints.

The architect-to-HVAC handoff contains the dated plan set and envelope assumptions. The HVAC designer returns the room-by-room load report, design temperatures, proposed zones, indoor and outdoor equipment locations, routes, condensate, filters, ventilation interface, controls, and the exact model families considered.

The HVAC-to-electrician handoff contains the equipment schedule, accessories, voltage and current data, circuit assumptions, auxiliary heat if any, controls, pumps, and outdoor-unit locations. The electrician returns the service and panel impact, circuit schedule, disconnect and protection design, and a list of unresolved jurisdiction questions.

The HVAC-to-builder handoff contains scaled routes and sequence requirements: sleeves, line-set supports, duct openings, return paths, equipment pads or brackets, roof or wall penetrations, drain routes, and protection during construction. The builder returns field dimensions and reports conflicts before framing or drywall closes them.

The HVAC-to-ventilation handoff states whether the system is separate or integrated, the outdoor-air path, controls, filtration, pressure concerns, condensate, and balancing requirements. The ventilation professional returns a design and a measured test plan. Do not let “ventilation by others” hide an unpriced system.

The team-to-homeowner handoff contains the decision record, bid comparison, approved submittals, permits and inspection records, commissioning results, manuals, warranty documents, maintenance schedule, filter sizes, control instructions, and service contacts.

### Normalize the bid before comparing price

Request every bidder to price the same scope sheet. The sheet should separate equipment, duct distribution, refrigerant piping, branch components, controls, electrical, ventilation, condensate, structural supports, penetrations, insulation, drywall or finish repair, testing, commissioning, permits and fees, start-up, owner training, and closeout documents.

Use three columns for each line item: included, excluded, or allowance. For an allowance, write the amount, unit, and assumption. “Electrical by others” is not a complete scope. It should identify the equipment data delivered to the electrician and the physical work the HVAC bidder expects from that trade.

Ask whether labor includes recovery or evacuation procedures, pressure testing, leak checking, insulation, labeling, line-set protection, duct sealing, balancing, filter racks, drain protection, and control setup. The homeowner should not instruct a technician how to handle refrigerant, but the homeowner can require the bid to identify the qualified party and the closeout evidence.

### A reproducible scoring worksheet

Use the following method for the three options. First, fill the factual fields from the same plans. Second, give each criterion a priority weight from 1 to 5 based on the household brief. Third, give each architecture a rating from 1 to 5 only when the proposal has evidence; use “unknown” rather than a generous score. Fourth, calculate the weighted score:

`weighted score = sum(priority weight × architecture rating) ÷ sum(priority weights)`

This score is an organizing device, not a prediction of energy bills, comfort, life-cycle cost, or equipment life. It cannot override a failed load, missing route, missing permit path, incompatible equipment combination, or unsafe installation.

| Criterion | Evidence to attach | Weight 1–5 | Ducted rating 1–5 | Ductless rating 1–5 | Mixed rating 1–5 |
|---|---|---:|---:|---:|---:|
| Closed-door room coverage | Zone drawing and room delivery plan |  |  |  |  |
| Duct or line-set route fit | Scaled plan, section, and OEM route check |  |  |  |  |
| Ventilation integration | Ventilation design and control sequence |  |  |  |  |
| Filtration and access | Filter data, location, size, replacement path |  |  |  |  |
| Humidity strategy | Latent-load and control response |  |  |  |  |
| Electrical fit | Electrician’s schedule and service review |  |  |  |  |
| Noise and appearance | Exact sound data and elevations |  |  |  |  |
| Service and maintenance | Access drawing and maintenance schedule |  |  |  |  |
| Future-room flexibility | Reserved route, space, or documented limit |  |  |  |  |
| Bid completeness | Scope comparison with exclusions |  |  |  |  |

Do not turn a missing field into a rating of 3. Unknown is a decision blocker. A system can score well and still be rejected because the proposed indoor and outdoor models do not form a verified combination or because the route cannot be built.

### Illustrative modeled example: one plan, three architectures

The following scenario is illustrative and must not be used to size equipment. It shows how to expose assumptions and sensitivity. Assume a two-story, 2,400-square-foot home with eight currently conditioned spaces. A future 400-square-foot office is reserved in the brief but is excluded from the current load table and both current totals. The illustrative room-by-room design loads are:

| Space | Heating load (Btu/h) | Cooling load (Btu/h) | Proposed zone question |
|---|---:|---:|---|
| Great room | 18,000 | 18,000 | Independent daytime zone |
| Kitchen and dining | 7,000 | 4,000 | Adjacent to great room but separate gains |
| Primary bedroom | 6,000 | 5,000 | Closed-door night zone |
| Bedroom 2 | 4,000 | 3,000 | Closed-door night zone |
| Bedroom 3 | 4,000 | 3,000 | Closed-door night zone |
| Lower suite | 8,000 | 6,000 | Independent zone |
| Hall and bath | 3,000 | 2,000 | Delivery and transfer question |
| Utility and circulation | 2,000 | 1,000 | Not automatically served by a head |
| **Illustrative total for eight current spaces** | **52,000** | **42,000** | **Not an equipment size** |

The future office remains a separate planning input: `5,000 Btu/h` heating and `3,000 Btu/h` cooling, both marked “not included in current total.” The numbers are simply inputs to demonstrate the worksheet. The formula for each current total is `sum(room loads for the eight current spaces)`: `18,000 + 7,000 + 6,000 + 4,000 + 4,000 + 8,000 + 3,000 + 2,000 = 52,000 Btu/h` heating and `18,000 + 4,000 + 5,000 + 3,000 + 3,000 + 6,000 + 2,000 + 1,000 = 42,000 Btu/h` cooling. The HVAC designer must replace them with the actual report, examine diversity and equipment performance, and select equipment using the applicable professional method and exact OEM data.

Option A, the illustrative ducted architecture, might reserve one air-handler location, a central return strategy, about 220 linear feet of combined supply and return duct drawn on the plan, two zones, one outdoor unit, and one main line set. Those lengths are modeled coordination inputs, not measurements or a recommendation. The architect would need to show a conditioned route, registers, returns or transfers, filter access, drain, and a path through both floors.

Option B, the illustrative ductless architecture, might show six indoor units serving the eight current spaces, three outdoor units, six line-set routes totaling 190 ft, and separate delivery or transfer solutions for the rooms without a dedicated head. The future office is not one of those six units; it is only a reserved future route question. Again, these are modeled inputs. The HVAC designer would need to verify whether the chosen outdoor units can support the selected indoor-unit combinations at the required temperatures and whether the room schedules create acceptable control behavior.

Option C, the illustrative mixed architecture, might show a short-duct indoor unit for the three bedrooms and hall, two ductless heads for the great room and kitchen, one ductless head for the lower suite, three outdoor units, 90 ft of short duct, and 150 ft of line sets. The mixed option reduces some visible heads but creates more coordination between systems, controls, returns, filters, drains, and service contacts.

Suppose the homeowner assigns these weights: closed-door coverage 5, route fit 4, ventilation integration 4, filtration 4, humidity 3, electrical fit 3, appearance 2, service 4, future flexibility 2, and bid completeness 5. The weights sum to 36. A fictional, illustrative rating set might be:

| Criterion | Weight | Ducted | Ductless | Mixed |
|---|---:|---:|---:|---:|
| Closed-door coverage | 5 | 5 | 3 | 5 |
| Route fit | 4 | 2 | 5 | 4 |
| Ventilation integration | 4 | 5 | 3 | 4 |
| Filtration | 4 | 5 | 2 | 4 |
| Humidity | 3 | 4 | 3 | 4 |
| Electrical fit | 3 | 3 | 4 | 3 |
| Appearance | 2 | 5 | 2 | 4 |
| Service | 4 | 4 | 3 | 3 |
| Future flexibility | 2 | 3 | 4 | 4 |
| Bid completeness | 5 | 4 | 3 | 3 |
| **Weighted score** | **36** | **4.06** | **3.19** | **3.81** |

The three scores are calculated as follows: ducted `(5×5 + 4×2 + 4×5 + 4×5 + 3×4 + 3×3 + 2×5 + 4×4 + 2×3 + 5×4) ÷ 36 = 146 ÷ 36 = 4.06`; ductless `(5×3 + 4×5 + 4×3 + 4×2 + 3×3 + 3×4 + 2×2 + 4×3 + 2×4 + 5×3) ÷ 36 = 115 ÷ 36 = 3.19`; mixed `(5×5 + 4×4 + 4×4 + 4×4 + 3×4 + 3×3 + 2×4 + 4×3 + 2×4 + 5×3) ÷ 36 = 137 ÷ 36 = 3.81`. Under these fictional weights and ratings, ducted leads, mixed is second, and ductless is third; that ordering is only a transparent illustration. These ratings are not observations, product tests, energy predictions, or a recommendation for this opportunity. They demonstrate a transparent formula and show why a homeowner should keep each rating tied to an evidence record.

![Illustrative decision matrix scoring heat-pump architectures against stated homeowner priorities](https://brictale.com/images/home/build/materials/compare-new-home-ducted-ductless-mixed-heat-pump-systems-before-design-freeze/architecture-decision-matrix.webp)

### Sensitivity: when the decision changes

Now model a different household priority: visible equipment and duct chases are unacceptable, route fit becomes 5, appearance becomes 5, filtration becomes 2, and closed-door coverage remains 5. Keep the illustrative ratings unchanged and recalculate. The new weight total is 38. Ducted becomes `(146 + 1×2 + 3×5 - 2×5) ÷ 38 = 153 ÷ 38 = 4.03`; ductless becomes `(115 + 1×5 + 3×2 - 2×2) ÷ 38 = 122 ÷ 38 = 3.21`; mixed becomes `(137 + 1×4 + 3×4 - 2×4) ÷ 38 = 145 ÷ 38 = 3.82`. Ductless does not overtake ducted under this unchanged-rating sensitivity; ducted remains first, mixed second, and ductless third. That does not make the ordering correct for a real project if the proposal lacks a closed-door delivery plan, ventilation design, model match, or service access.

This sensitivity test is valuable because it distinguishes a preference conflict from a technical blocker. If a homeowner changes a preference and the preferred architecture changes, document the new preference. If an architecture fails a must-have—such as a room load, an OEM route limit, an electrical service constraint, or an AHJ requirement—do not rescue it with a higher subjective rating.

### The second handoff

Send the completed matrix, illustrative or actual route schedule, and the homeowner’s must-haves to the HVAC designer. Ask for a written response to every unknown. The designer should return exact system candidates, expanded performance at the project temperatures, indoor-unit combinations, line-set and branch checks, control sequence, and the parts of the matrix that cannot be verified until installation.

The next decision is whether the leading architecture can pass technical verification and produce a bid that includes all physical work.

## Verify capacity, compatibility, electrical, and ventilation before approval

Approve an architecture only after the professional design package shows room loads, operating conditions, exact OEM data, compatible indoor and outdoor components, electrical implications, ventilation, condensate, and a commissioning plan. Ratings, marketing pages, and nominal capacity labels are screening evidence; they are not release evidence.

### Check capacity at the conditions that matter

Ask for capacity at the heating design temperature, cooling design temperature, and any low-temperature condition that matters to the location. Ask whether the published values are rated, interpolated, or taken from an expanded performance table, and whether the control strategy or supplemental heat changes the result. Ask how the system behaves at minimum capacity when the load is small, especially in a low-load new home.

Do not calculate equipment size by dividing a total Btu/h load by 12,000 and rounding up. That can be a rough unit conversion, not a design method. A professional must consider the selected system’s available capacity range, staging, fan airflow, indoor-unit limits, sensible and latent performance, defrost behavior, auxiliary heat, and the actual load distribution.

ENERGY STAR warns that oversized equipment may cycle too frequently and reduce comfort, while poor airflow can reduce efficiency, increase utility bills, create dampness, reduce comfort, and shorten equipment life. [Use its sizing and airflow guidance as a review question](https://www.energystar.gov/saveathome/heating-cooling/hvac-quality-installation). The homeowner’s record should therefore include the load report and the performance evidence, not just a model number.

### Verify the indoor and outdoor combination

For every candidate, record the exact outdoor model, indoor model or models, branch box if applicable, controls, accessories, refrigerant type, line-set sizes, line-set lengths, elevation, and the document revision used. Ask the HVAC designer to identify the matching performance record or the manufacturer’s application table supporting the combination.

Ask the HVAC designer to provide a current AHRI certificate or reference when the exact combination is certified, or the exact OEM certification, application table, or expanded-performance record when that is the applicable evidence. Save the document or reference with the model numbers, revision, and date reviewed. The archived ACCA protocol recognizes a matched system through AHRI or CEE directory certification or OEM certification/performance data; [review its matched-system and installation-file guidance](https://www.energystar.gov/ia/home_improvement/home_contractors/QI_Verification_Protocols.pdf). Do not treat a family name, a marketing label, or an unverified seller statement as proof that your exact combination and rating are supported. If a ductless multi-zone combination is not represented by the relevant certification record, ask the designer to show the exact OEM expanded-performance and compatibility evidence and state what the record does and does not cover.

The verification record should say “matched” only when the actual components and the applicable source agree. A matched system is not necessarily the best architecture, and an unmatched combination is not made acceptable by a good brand reputation.

### Verify duct design and airflow

For each ducted section, record design airflow, supply and return path, duct dimensions, material, insulation or enclosure, expected static pressure, terminal locations, filter pressure drop, and balancing method. Ask who will calculate the duct design and who will field-measure airflow. The homeowner should receive the design airflow and the measured result by room or terminal where the commissioning scope supports it.

ENERGY STAR’s quality-installation guidance says airflow should meet manufacturer performance specifications and asks contractors to evaluate ducts and perform leakage testing where appropriate. [Review the ENERGY STAR installation questions](https://www.energystar.gov/saveathome/heating-cooling/hvac-quality-installation). The archived ACCA verification protocol linked through ENERGY STAR describes installation-file review and field verification, and lists design airflow, measured airflow, supply and return static pressure, duct leakage, and terminal airflow as reportable elements. [Review the protocol’s sample measurement fields](https://www.energystar.gov/ia/home_improvement/home_contractors/QI_Verification_Protocols.pdf).

Do not use a duct leakage target from another program, code edition, climate, or certification path without naming that source and confirming applicability. The actual project’s adopted code and program requirements belong to the project jurisdiction and the program administrator. If ducts are all inside the thermal envelope, still verify airflow, balance, noise, filters, and access; “inside” is not a substitute for correct design.

### Verify line sets and refrigerant work without doing it yourself

The homeowner can compare the drawn line-set lengths and access. The qualified HVAC contractor must verify pipe sizes, maximum lengths, vertical rises, branch connections, insulation, pressure testing, evacuation, charge calculation, leak checks, and final operation according to the exact OEM instructions and applicable rules. Keep the homeowner’s role to observation, documentation, and questions.

EPA Section 608 is a United States federal requirement for covered refrigerant work; state or local licensing and permit requirements may also apply. [Use the EPA certification page to understand the federal boundary](https://www.epa.gov/section608/section-608-technician-certification-requirements). Ask for the responsible technician’s credentials where applicable, the model-specific start-up record, and the final refrigerant-related measurements. Do not attach gauges, add refrigerant, open a circuit, or ask an unqualified helper to do so.

### Verify electrical design with the electrician

Give the electrician the final equipment schedule, not an early brochure. Ask for a written check of service capacity, panel space, feeder implications, circuit routes, disconnects, equipment grounding and protection, controls, condensate pumps, ventilation equipment, auxiliary heat, and any future-room allowance. The exact jurisdiction must be identified on the electrical plan; no national permit or circuit rule should be assumed from this article.

A ductless proposal with multiple outdoor units can create more outdoor disconnect and circuit locations. A ducted proposal with auxiliary electric heat can create a different peak demand. A mixed system can combine both. The number of outdoor units is therefore a coordination variable, not a score by itself.

The homeowner’s verification question is simple: “Does the electrical schedule name every heat-pump component and accessory, and has the electrician reviewed the actual data against this service and this jurisdiction?” If not, approval is premature.

### Verify ventilation and filtration as installed systems

Before move-in, keep a dedicated mechanical-ventilation verification record for design airflow, measured airflow, controls, responsibility, and follow-up. Do not let that record be implied by the heat-pump start-up sheet.

The ventilation professional should provide a design airflow in cfm, intake and exhaust locations, controls, filters, sound expectations, condensate if applicable, and a field-verification method. The HVAC and architect should show penetrations, access, and any interaction with the air handler or controls. The builder should preserve the ducts, sleeves, dampers, and access panels through construction.

At closeout, record measured ventilation airflow and control operation if those measurements are part of the project scope or program. DOE’s selected-southeastern-states study is a useful warning that installed ventilation can differ from intended ventilation; the article does not turn its regional findings into a national requirement. [Use DOE’s measured study to justify checking installed airflow](https://www.energy.gov/cmei/buildings/ventilation-and-indoor-air-quality-recently-constructed-us-homes-measured-data).

For filtration, record the exact filter dimensions, rated performance or applicable manufacturer information, pressure-drop limitation, access, replacement interval, and annual supply cost. If a ductless unit’s standard filter is washable, record the washing and drying procedure from the OEM manual. If an added filter covers only part of the flow path, do not represent it as whole-home filtration.

### Verify warranties as scope documents

A warranty is not a promise that every part of the installed system will be repaired for free. It is a document with a defined product, territory, installer condition, exclusions, registration rule, maintenance expectation, and process.

For example, the Mitsubishi Electric Trane HVAC US residential warranty revised June 1, 2026 defines covered connected indoor and outdoor units and, where required, a branch box, while excluding refrigerant piping, electrical wiring, controls, and accessories from that product definition. [Read the exact Mitsubishi warranty scope](https://dw2p0k56b2hr9.cloudfront.net/Residential_HM_WR_HX_WX_Heat_Pump_Systems_06012026_83a52e2c28.pdf). This is a model-family-specific example, not a claim about every manufacturer.

The same warranty says its coverage applies to licensed-HVAC-contractor installation following applicable building codes and permits, manufacturer instructions, and good trade practices; it also identifies proper matching, sizing, specification, and scheduled maintenance as relevant conditions. [Review the installation and maintenance terms](https://dw2p0k56b2hr9.cloudfront.net/Residential_HM_WR_HX_WX_Heat_Pump_Systems_06012026_83a52e2c28.pdf). Ask the bidder to state who pays labor, access, controls, piping, electrical work, pumps, and maintenance because those may not be covered parts.

Use the manufacturer’s current literature index to collect the exact installation, operation, application, control, and warranty documents for every model and accessory. [Open the Mitsubishi literature library](https://www.mitsubishicomfort.com/literature). Save the document title, revision, model numbers, and date reviewed. Do not use a discontinued PDF or a page for a neighboring model as proof of current compatibility.

### Technical approval gate

Mark each item pass, fail, or unresolved:

- Room loads: current plan, stated assumptions, design temperatures, and professional sign-off.
- Capacity: exact equipment performance at relevant outdoor temperatures and operating modes.
- Combination: exact indoor/outdoor/branch/control combination supported by AHRI or OEM evidence.
- Ducts: design airflow, route, boundary location, returns, filter, access, leakage and balance plan.
- Line sets: drawn route, length, elevation, size, protection, condensate, and OEM limit check.
- Ventilation: outdoor-air design, controls, access, filtration and field-verification method.
- Electrical: exact model data, circuits, service/panel review, disconnects, controls and pumps.
- Condensate: every drain, pump, overflow or protection detail, termination and access.
- Noise and appearance: model data plus plan/elevation review in the actual rooms.
- Maintenance: filters, coils, drains, service access, parts and owner schedule.
- Warranty: exact terms, installer condition, registration, exclusions, labor and documents.

One unresolved item may be acceptable during schematic design if it has an owner and due date. It is not acceptable at design freeze if it could force a route, equipment, panel, ceiling, wall, or finish change.

The next decision is whether the verified option is ready to become a contract scope and a frozen plan.

## Use a bid and handoff record that survives design changes

The contract scope should name every physical and documentary deliverable needed to carry the selected architecture from plan to operation. If an item is “by others,” the record must name the other party, the interface, the due date, and the acceptance evidence.

### The scope sheet

Create one line for each of the following and mark included, excluded, or allowance:

| Scope family | Questions the bid must answer | Handoff evidence |
|---|---|---|
| Load and selection | Who provides the current load report and model selection? | Dated load report and submittal |
| Outdoor units | How many, where, on what support, with what service path? | Site plan, elevation, support detail |
| Indoor units or air handler | Exact locations, types, controls, filters, backing and access? | Floor plan, ceiling plan, model list |
| Ducts | Supply, return, transfer, insulation, sealing, balancing? | Duct plan, airflow schedule, test plan |
| Refrigerant piping | Line-set size, route, protection, supports, insulation and charge? | OEM route check and start-up record |
| Branch components | Branch box, headers, fittings, access and labeling? | Compatibility record and access detail |
| Electrical | Equipment circuits, disconnects, controls, pumps, auxiliary heat? | Electrician’s schedule and inspection record |
| Ventilation | Equipment, intake, exhaust, filtration, controls, balancing? | Ventilation plan and measured airflow |
| Condensate | Gravity route, pump, overflow, discharge, access? | Drain detail and functional test |
| Framing and finishes | Sleeves, backing, chases, bulkheads, fire or air sealing? | Framing walk and photo record by owner/team |
| Commissioning | What measurements, at what conditions, by whom? | Signed start-up and commissioning record |
| Owner training | What is demonstrated and which manuals remain? | Owner sign-off and document index |

The table is not a permit form or a substitute for the construction contract. It is a way to expose missing scope before the contract price makes the omission expensive.

### Revision control

Name each issue: architectural plan date, load-report date, mechanical plan date, electrical schedule date, ventilation design date, equipment-submittal date, and bid date. On the comparison sheet, record which version each architecture used. If the great room window changes, the ceiling drops, or the panel moves, identify which documents must be rechecked.

Require a change notice when a field conflict alters indoor-unit location, duct route, line-set length, outdoor-unit location, electrical data, ventilation path, drain, filter access, or warranty condition. The homeowner should receive the consequence in plain language: added cost, schedule effect, comfort risk, maintenance effect, and which professional must approve the change.

### Sequence around the design freeze

The design sequence should be coordinated, even if the contracts are separate:

1. Homeowner confirms rooms, schedules, comfort priorities, appearance limits, future spaces, and project jurisdiction.
2. Architect issues a current plan and envelope assumptions.
3. HVAC designer prepares the room-by-room load report and proposes zones.
4. Architect and HVAC designer test duct, line-set, indoor-unit, outdoor-unit, drain, access, and ventilation routes in plan and section.
5. HVAC designer proposes exact candidate combinations and performance evidence.
6. Electrician reviews the equipment schedule against service, panel, circuits, controls, and local requirements.
7. Ventilation professional coordinates outdoor air, exhaust, filters, controls, access, and measurement.
8. Builder prices all scope lines, allowances, penetrations, framing, finishes, tests, and closeout.
9. Homeowner compares normalized bids and records the selected architecture and reasons.
10. The architect issues the frozen coordination set with unresolved items closed or explicitly deferred outside the freeze.

Freezing the design does not mean the homeowner can never change the system. It means the team has agreed on the version from which routes, openings, electrical work, bids, and later verification will be built. A later change should be treated as a controlled change, not a verbal substitution.

### Common bid failure cases

**The low bid omits distribution.** A quote shows the outdoor and indoor units but not ducts, grilles, line-set protection, branch components, drains, controls, or commissioning. Compare the scope sheet, then obtain a corrected price. Do not infer that “complete installation” includes work that is not listed.

**The bid changes the architecture without saying so.** One bidder quotes a central ducted system, another quotes several ductless heads, and a third quotes a mixed system. They cannot be compared by total price. Ask every bidder to price the same architecture first or label the proposals as different design alternatives.

**The route is an allowance.** A line-set route or duct chase is priced as a generic allowance without length, penetrations, supports, access, or finish repair. Require the drawn route and the allowance assumptions before award.

**The ventilation scope says “code compliant.”** That phrase may be too vague because the applicable adopted code and program, if any, are location-specific. Require the named jurisdiction, adopted edition or program, designed airflow, equipment, controls, and test record.

**The equipment schedule is a family name.** “Cold-climate inverter heat pump” or “multi-zone mini-split” is not an exact model combination. Require the submittal with indoor, outdoor, branch, control, accessory, and document revision identifiers.

**The builder closes access.** Ceiling, wall, attic, and closet access is treated as a finish decision after the mechanical plan. Put access panels, filter doors, service clearances, and replacement paths on the architectural and mechanical sheets before framing.

**The warranty is shown as a sales bullet.** A long parts warranty may not cover labor, piping, wiring, controls, accessories, damage from improper matching, missed maintenance, or work outside the stated installer conditions. Read the exact warranty and put its practical exclusions in the bid record.

### The homeowner’s contract questions

Ask each lead bidder to answer in writing:

- Who prepared the load calculation, and will it be updated if the plan changes?
- Who owns the equipment selection and compatibility check?
- Who draws and verifies ducts, line sets, condensate, ventilation and controls?
- Who is responsible for sleeves, backing, structural supports, fire or air sealing, and finish repair?
- Who pulls each permit or coordinates each inspection, and which actual authority is involved?
- Who performs start-up and commissioning, and what measurements are delivered?
- What happens if the proposed model is unavailable before installation?
- Can a substitute change capacity, efficiency, line-set limits, electrical requirements, controls, filters, or warranty?
- Who demonstrates the system and hands over manuals, records, model numbers and maintenance instructions?

The homeowner should not be asked to approve a substitute from a phone photograph. Require the same technical and scope review as the original selection.

### The third handoff

If a model or system changes before rough-in, issue a written heat-pump substitution handoff and repeat the capacity, compatibility, route, electrical, controls, warranty, bid, and permit review before releasing the change.

At contract award, issue the selected architecture worksheet, final matrix, exact submittal, coordinated plan set, scope sheet, jurisdiction record, responsibility map, and acceptance checklist. Every party should know which document controls if two drawings disagree. The next decision is when to inspect rough-in and what evidence must exist before the system is closed behind finishes.

## Release the system only after commissioning and warranty evidence

Accept the installed heat-pump architecture only when the field installation matches the frozen plans, the qualified professionals have completed their required checks, the system operates as designed, and the homeowner receives a usable record of what was installed and how to maintain it. A successful power-on is not the same as commissioning.

### Rough-in verification before closing walls

Before insulation, drywall, ceilings, or inaccessible finishes close the work, walk the routes against the approved plan. Photograph and label, subject to the project team’s documentation practice:

- Duct sizes, insulation or enclosure, returns, transfers, dampers and filter locations.
- Refrigerant line-set sizes, route, supports, penetrations, insulation and access.
- Indoor-unit backing, framing, drain and access panel locations.
- Outdoor-unit support, vibration isolation, service path and line entry.
- Electrical conduits, circuits, disconnects, grounding, controls and pump power.
- Ventilation intake, exhaust, filters, dampers, controls and access.
- Condensate drains, slopes, pumps, overflow protection, cleanouts and discharge.
- Sleeves, air sealing, weather sealing, fire stopping, and finish interfaces as specified by the responsible professionals.

The homeowner can attend and ask questions. The homeowner should not remove guards, enter unsafe areas, test live circuits, climb unprotected heights, pressurize lines, or approve concealed work that the responsible professional has not reviewed.

![Heat-pump design-freeze release path from plans and load checks to commissioning records](https://brictale.com/images/home/build/materials/compare-new-home-ducted-ductless-mixed-heat-pump-systems-before-design-freeze/design-freeze-release-gate.webp)

### Startup and commissioning record

Ask the HVAC contractor to provide a start-up and commissioning record with the exact installed models and serial numbers, date, outdoor conditions, indoor conditions, controls, operating mode, and test instruments or methods where relevant. Depending on the system and scope, request:

- Measured airflow and design airflow for ducted terminals or air handlers.
- Supply and return static pressure or the OEM-required airflow verification.
- Refrigerant type and the OEM-required pressure, temperature, charge, or electronic checks performed by the qualified technician.
- Electrical voltage, current, disconnect and control checks performed by the electrician or HVAC professional as assigned.
- Indoor-unit communication, sensor, thermostat, schedule, mode and fault-code checks.
- Condensate drain or pump test, overflow response, and visible discharge check.
- Ventilation airflow, control operation, intake and exhaust verification.
- Duct leakage and air balance measurements where the project scope, program, or design requires them.
- Outdoor-unit operation, defrost or low-temperature control behavior as applicable to the selected equipment.
- Owner demonstration, filter sizes, maintenance schedule and service contacts.

ENERGY STAR’s contractor resources describe assessing installed performance relative to design and identify measurements such as blower airflow, blower watt draw, and refrigerant charge. Its quality-installation materials also point to duct leakage and airflow evidence. [Use the ENERGY STAR resources to shape the project’s commissioning request](https://www.energystar.gov/partner-resources/residential_new/working/hvac/Requirements_Resources). The exact required tests depend on the equipment, contract, code, program, and professional scope; do not copy a voluntary checklist and call it legal compliance.

### Observe, interpret, and do not infer

**Observe:** a room is warmer or cooler than the setpoint during the first occupied week. **Interpret:** record outdoor temperature, indoor temperature at occupant level, setpoint, door position, operating mode, and whether the equipment is in defrost or a scheduled setback. **Do not infer:** that the equipment is undersized or defective from one observation. **Next step:** send the record to the HVAC contractor and compare it with the design and commissioning data.

**Observe:** a ductless indoor unit appears to run continuously. **Interpret:** record mode, setpoint, outdoor conditions, room temperature, and whether the unit is modulating. **Do not infer:** that continuous operation means failure; variable-capacity equipment may operate at low output. **Next step:** ask the contractor to review operating data and controls.

**Observe:** a ducted room has weak airflow. **Interpret:** check that the register is open, the filter is correctly installed, and the door or transfer path is as designed; do not remove panels or access live equipment. **Do not infer:** that a larger unit will solve the issue. **Next step:** request measured terminal airflow, static pressure, balance, duct leakage, and filter-pressure review.

**Observe:** indoor humidity remains high. **Interpret:** record indoor temperature and relative humidity, outdoor conditions, ventilation operation, cooling mode, and occupancy or moisture sources. **Do not infer:** that the heat pump category alone determines dehumidification. **Next step:** ask the designer or contractor to compare latent-load assumptions, equipment control, ventilation, and any separate dehumidification plan.

**Observe:** water appears at an indoor unit or drain termination. **Interpret:** stop using the affected component if the contractor advises, protect finishes, and document the location and operating state. **Do not infer:** that adding a pan or pouring a cleaner is an adequate repair. **Next step:** call the qualified HVAC contractor to inspect the drain, pump, slope, insulation, and overflow path.

**Observe:** an outdoor unit is louder than expected. **Interpret:** record time, operating mode, distance, nearby room, surface, weather, and whether the sound is fan, compressor, vibration or defrost related. **Do not infer:** that a sound rating from a different model or test condition predicts the room experience. **Next step:** ask the contractor to verify installation, supports, clearances, controls, and the exact OEM sound data.

### Safety boundaries for this decision

Electrical work, service-panel changes, disconnects, live testing, grounding, overcurrent protection, and wiring belong to the qualified electrical professional under the actual state and local requirements. Refrigerant piping, gauges, charging, recovery, evacuation, and circuit opening belong to the appropriately qualified HVAC technician; United States EPA Section 608 requirements apply to covered refrigerant work. Structural supports, roof penetrations, framing alterations, and concealed fire, air, or weather sealing belong to the responsible design and construction professionals.

Work at height, attic or crawlspace access, lifting outdoor units, roof work, ladder work, and confined or poorly ventilated spaces can injure occupants and workers. The homeowner can review plans, measurements, labels, scope, and records from a safe location. The homeowner should not improvise a lift, enter an unsafe crawlspace, bypass a control, drill a structural member, or open a refrigerant or electrical enclosure.

If you see or smell suspected mold, biofilm, slime, staining, or other contamination in a ductless head, filter housing, drain pan, grille, air handler, or ventilation/filtration component, do not diagnose it remotely from a photograph or disassemble the equipment to investigate. Do not disturb, scrape, brush, spray cleaner or biocide, or restart an affected HVAC component in a way that could spread material. Limit exposure, keep occupants away from the affected area, and document the condition without touching it. Ask a qualified HVAC professional to assess the equipment and moisture source; if the condition may extend into building materials or requires indoor-air or remediation judgment, refer it to an experienced qualified indoor-air or environmental professional. EPA says not to run an HVAC system known or suspected to be contaminated with mold because it could spread mold, and directs homeowners to consult its HVAC-cleaning guidance before further action. [Follow EPA’s mold and HVAC guidance](https://www.epa.gov/mold/mold-cleanup-your-home).

The AHJ and jurisdiction must be named for the project. A permit or inspection result is not a substitute for the homeowner’s comparison, and this remote article cannot assess the site, workmanship, fire separation, electrical service, equipment clearance, refrigerant installation, drainage, ventilation, or local code compliance. Ask the actual authority and the responsible licensed professionals.

### Closeout and ownership file

The final homeowner file should contain the approved plan revision, as-built changes, equipment submittals, serial numbers, AHRI reference or OEM compatibility record where applicable, load report, electrical schedule, ventilation design and measurements, commissioning report, permits and inspection records from the actual authorities, warranties, registration confirmation, manuals, filter information, maintenance schedule, service contacts, and owner training notes.

The owner should be able to answer five questions without calling the builder:

1. Which rooms does each system serve, and what should happen when doors are closed?
2. Where are the filters, drains, access panels, outdoor units, disconnects and controls?
3. Which maintenance can the owner safely perform, and which work needs a qualified professional?
4. Which exact models and accessories are installed, and which warranty document applies?
5. What record should be supplied if comfort, noise, humidity, airflow, water, or electrical problems appear?

For ductless systems, include the filter-cleaning and indoor-unit cleaning guidance for the exact model. PNNL’s residential resource says a typical manufacturer recommendation is to clean standard mesh filters about every two weeks and that deep cleaning depends on buildup, use and conditions; the OEM schedule controls your home. [Keep the PNNL maintenance warning with the owner file](https://basc.pnnl.gov/resource-guides/ductless-mini-split-heat-pumps).

### Final design-freeze release gate

Release the selected ducted, ductless, or mixed architecture only when the homeowner signs the decision record and the professionals close the technical gates:

- **Brief gate:** room uses, schedules, closed-door expectations, appearance, noise, filtration, humidity, future rooms and maintenance priorities are recorded.
- **Load gate:** current room-by-room loads, design temperatures and assumptions are attached.
- **Coverage gate:** every room has an intentional delivery, zone, return or transfer strategy.
- **Route gate:** ducts, line sets, controls, drains, ventilation, electrical paths, supports and service access are shown in plan and section.
- **Compatibility gate:** exact models and accessories agree with OEM tables and the current AHRI or other applicable certification evidence.
- **Electrical gate:** the electrician has reviewed the exact schedule against the service, panel, circuits and actual jurisdiction.
- **Ventilation gate:** the outdoor-air strategy, controls, filtration and field verification are assigned.
- **Scope gate:** each trade’s inclusions, exclusions, allowances, permits, finish work and commissioning duties are priced.
- **Warranty gate:** the exact warranty, installer conditions, registration, maintenance, exclusions and labor responsibility are in the owner file.
- **Construction gate:** rough-in inspection timing and the evidence required before closing walls are agreed.
- **Commissioning gate:** the acceptance measurements and owner training are part of the contract, not an afterthought.

If one gate is unresolved, record the owner, due date, consequence, and whether the issue can be resolved without reopening frozen plans. If it cannot, keep the design open. The most useful next decision is then specific: revise the room coverage, move the mechanical space, reserve a larger chase, split a zone, change the ventilation strategy, update the electrical service, select a different compatible combination, or reject the architecture.

### The decision in one sentence

Choose ducted when the home benefits from hidden, centralized distribution, accessible filtration, and deliberate closed-door coverage and can afford the space and route. Choose ductless when room-by-room control and reduced duct infrastructure are more valuable and the indoor-unit, ventilation, filtration, drain, and appearance plan is complete. Choose mixed when the plan genuinely has two different distribution problems and the added controls, routes, service records, and warranty boundaries are fully coordinated. Carry forward only the option that can prove every claim with the same plans, exact equipment evidence, named responsibilities, and a commissioning record.

## Evidence

- PNNL Building America says a ductless design should use heating and cooling load calculations for the spaces served, determine indoor- and outdoor-unit locations, use equipment-selection methods, assess the electrical system, and commission the completed system. [Ductless (Mini-Split) Heat Pumps](https://basc.pnnl.gov/resource-guides/ductless-mini-split-heat-pumps). Scope: Building America Solution Center guidance for residential ductless heat-pump planning and installation; the cited scope is process guidance, not a project-specific design or national code requirement.. Accessed: 2026-09-08.
- PNNL identifies space for ducts and a central air handler, conditioned area, zoning, ventilation configuration, cooling and heating efficiency, dehumidification, cold-climate capacity, filtration, and noise as comparison parameters, and notes that individual models must be compared because general technology trends are not inherent to every system. [Ductless (Mini-Split) Heat Pumps](https://basc.pnnl.gov/resource-guides/ductless-mini-split-heat-pumps). Scope: PNNL Building America residential ductless-versus-ducted discussion; trends are explicitly general and model-dependent.. Accessed: 2026-09-08.
- PNNL explains that ducts and air handlers outside the conditioned space can lose heating and cooling through leakage and conduction, while locating them inside the thermal boundary can avoid treating that transferred energy as a loss to outdoors. [Ductless (Mini-Split) Heat Pumps](https://basc.pnnl.gov/resource-guides/ductless-mini-split-heat-pumps). Scope: Building America discussion of duct location and distribution losses; no universal loss percentage is used in this article.. Accessed: 2026-09-08.
- PNNL says standard ductless mesh filters commonly have low particulate capture, describes a typical manufacturer recommendation to clean them about every two weeks, and recommends evaluating wall-mounted blower-wheel buildup and deep-cleaning needs based on use and conditions. [Ductless (Mini-Split) Heat Pumps](https://basc.pnnl.gov/resource-guides/ductless-mini-split-heat-pumps). Scope: PNNL Building America residential guidance; exact filter design, cleaning interval, and service method remain model- and manufacturer-specific.. Accessed: 2026-09-08.
- PNNL illustrates that supplemental filters on some ductless wall units cover only a small part of the overall filter area, so most air can bypass the supplemental filter and receive minimal additional filtration benefit. [Ductless (Mini-Split) Heat Pumps](https://basc.pnnl.gov/resource-guides/ductless-mini-split-heat-pumps). Scope: PNNL Building America example of a supplemental filter design on a ductless wall unit; it is not a statement about every model or accessory.. Accessed: 2026-09-08.
- PNNL says single-zone 115/120 V ductless heat pumps are available on the market in sizes from 6,000 to 12,000 Btu/h and describes modest current draw that can allow some installations on lightly loaded existing 15 A and 20 A, 120 V circuits; this is an available configuration, not a universal circuit rule. [Ductless (Mini-Split) Heat Pumps](https://basc.pnnl.gov/resource-guides/ductless-mini-split-heat-pumps). Scope: PNNL Building America electrical discussion of certain single-zone ductless products and existing-circuit examples; exact model data and project electrical design control.. Accessed: 2026-09-08.
- A DOE Building America new-construction project developed a duct-design methodology using calculations to select the number of ducts for each zone and evaluated air-delivery materials and layouts through testing and modeling under stated enclosure assumptions. [Plug-and-Play Duct System Evaluation](https://www.energy.gov/cmei/buildings/plug-and-play-duct-system-evaluation). Scope: DOE project information for a specific plug-and-play duct approach in cold-climate new construction; it is not a universal duct-size prescription.. Accessed: 2026-09-08.
- DOE reports that a field study of 51 recently built homes in Florida, Georgia, and South Carolina measured ventilation equipment, airflow, and leakage; it found that most homes did not meet ASHRAE 62.2 requirements and that properly working whole-house ventilation was associated with lower measured concentrations of several pollutants in that study. [Ventilation and Indoor Air Quality in Recently Constructed U.S. Homes: Measured Data from Select Southeastern States](https://www.energy.gov/cmei/buildings/ventilation-and-indoor-air-quality-recently-constructed-us-homes-measured-data). Scope: DOE/FSEC measured study in selected hot-humid and mixed-humid southeastern states; findings do not establish a universal rate or local code requirement.. Accessed: 2026-09-08.
- ENERGY STAR advises that equipment should be designed and sized from the actual characteristics of the home rather than a rule of thumb, and that airflow should meet manufacturer performance specifications; it also calls for checking refrigerant charge and evaluating duct leakage where ducts exist. [HVAC Quality Installation](https://www.energystar.gov/saveathome/heating-cooling/hvac-quality-installation). Scope: U.S. EPA ENERGY STAR homeowner guidance; it is quality-installation guidance, not a substitute for the project’s adopted code or professional design.. Accessed: 2026-09-08.
- ENERGY STAR commissioning resources describe post-installation assessment against design and identify measurements such as blower airflow, blower watt draw, and refrigerant charge; the ACCA verification protocol also reports system matching, electrical, ventilation, duct leakage, airflow, and air-balance elements. [Requirements & Resources for HVAC Contractors and HVAC Quality Installation Verification Protocols](https://www.energystar.gov/partner-resources/residential_new/working/hvac/Requirements_Resources). Scope: ENERGY STAR residential new-home program resources and linked ACCA verification protocol; program participation and the protocol are not automatically required for every U.S. home.. Accessed: 2026-09-08.
- The ACCA HVAC Quality Installation Verification Protocol describes reviewing an HVAC installation file and verifying field measurements, and its reporting examples include design and measured airflow, supply and return static pressure, duct leakage, and terminal airflow; it also recognizes a matched system through AHRI or CEE directory certification or OEM certification/performance data. [HVAC Quality Installation Verification Protocols (ANSI/ACCA 9 QVIP - 2009)](https://www.energystar.gov/ia/home_improvement/home_contractors/QI_Verification_Protocols.pdf). Scope: Archived voluntary ACCA quality-installation verification protocol hosted by ENERGY STAR; it is guidance for a verification effort, not an automatic legal, code, or contract requirement for every U.S. home.. Accessed: 2026-09-08.
- EPA says Section 608 regulations require technicians who maintain, service, repair, or dispose of equipment that could release refrigerants to be certified, including activities such as attaching gauges or adding or removing refrigerant. [Section 608 Technician Certification Requirements](https://www.epa.gov/section608/section-608-technician-certification-requirements). Scope: United States federal Clean Air Act Section 608 and 40 CFR Part 82, Subpart F; state and local licensing, permit, and supervision rules may add requirements.. Accessed: 2026-09-08.
- The Mitsubishi Electric Trane HVAC US residential limited-warranty statement revised June 1, 2026 defines the covered product as specified connected indoor and outdoor units and, when required, a branch box, while excluding refrigerant piping, electrical wiring, controls, and accessories from that product definition. [Limited Warranty Statement: Residential M-Series, P-Series and SMART MULTI Split Air Conditioner and Heat Pump Systems](https://dw2p0k56b2hr9.cloudfront.net/Residential_HM_WR_HX_WX_Heat_Pump_Systems_06012026_83a52e2c28.pdf). Scope: The named Mitsubishi residential model families and U.S. coverage territory in the June 1, 2026 warranty statement; other manufacturers and models have different terms.. Accessed: 2026-09-08.
- The same Mitsubishi warranty statement says its coverage applies to products installed by licensed HVAC contractors in accordance with applicable building codes and permits, manufacturer instructions, and good trade practices, and says registration, proper installation, matching, sizing, specification, and scheduled maintenance can affect enhanced coverage or claims. [Limited Warranty Statement: Residential M-Series, P-Series and SMART MULTI Split Air Conditioner and Heat Pump Systems](https://dw2p0k56b2hr9.cloudfront.net/Residential_HM_WR_HX_WX_Heat_Pump_Systems_06012026_83a52e2c28.pdf). Scope: The named Mitsubishi residential model families and U.S. coverage territory in the June 1, 2026 warranty statement; warranty terms must be reread for the exact selected model and purchase date.. Accessed: 2026-09-08.
- Mitsubishi’s U.S. literature library separates ducted, ductless, efficiency, and energy-recovery-ventilator materials, which is a reminder to obtain the exact installation, operation, application, and warranty documents for the proposed system rather than relying on a product-family page. [Literature](https://www.mitsubishicomfort.com/literature). Scope: Manufacturer literature index; the applicable document set depends on the selected model, controls, accessories, and installation.. Accessed: 2026-09-08.
- EPA says that when a heating, ventilation, or air-conditioning system is known or suspected to be contaminated with mold, the system should not be run because it could spread mold throughout the building, and homeowners should consult EPA’s HVAC-cleaning guidance before taking further action. [Mold Cleanup in Your Home](https://www.epa.gov/mold/mold-cleanup-your-home). Scope: U.S. EPA homeowner mold-cleanup guidance; the article applies this boundary conservatively to suspected contamination in residential heat-pump and ventilation components, while the qualified professional determines the site-specific assessment and remediation method.. Accessed: 2026-09-08.