Installation of a HITACHI airHome Multi dual-zone multizone heat pump in Châteauguay
Installation in Châteauguay of a HITACHI airHome Multi dual-zone, wall-mounted multi-zone heat pump, positioned to better withstand snow and provide independent heating and cooling in two zones.
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A compact installation designed for two comfort zones in a Châteauguay property
In Châteauguay, the space available around a home sometimes requires very precise installation choices. For this project, we had to integrate a HITACHI airHome Multi multi-zone heat pump into a relatively narrow side passage, between a wooden structure, a brick wall, and a concrete structure located immediately nearby.
The chosen solution is a dual-zone system, meaning a single outdoor unit supplies two separate indoor units. This configuration makes it possible to cool and heat two rooms or areas of the home while maintaining independent temperature control in each zone.
In the installation photo, the HITACHI outdoor unit is mounted on sturdy wall brackets, above ground level. This choice is not purely aesthetic. In Châteauguay’s climate, as elsewhere in Montreal, Laval, Longueuil, on the North Shore and the South Shore, the height of the outdoor unit directly affects its protection from snow, ice, fallen leaves, splashes, and moisture buildup.
Why was a dual-zone heat pump suitable for this home?
A single-zone wall-mounted heat pump can be very effective when only one open area needs to be treated. However, it becomes less suitable when uniform comfort must be maintained in two separate spaces, for example:
- a living room and a bedroom;
- a ground floor and an upper floor;
- a main living area and a closed office;
- two bedrooms used at different times;
- a home addition and the existing part of the building.
With the HITACHI airHome Multi, each indoor unit has its own setpoint, fan speed, and settings. One zone can also be turned off while the other remains operating.
However, the general operation must be clearly understood: units connected to the same outdoor unit use the same main mode. In summer, they operate in cooling, dehumidification, or fan mode. In winter, they use heating or fan mode. Therefore, one unit cannot heat a room while the other cools a second room at the same time.
This explanation is important when planning a multi-zone HVAC installation, as it prevents expectations that are incompatible with the equipment’s actual operation.
An outdoor unit installed on the wall rather than placed on the ground
The visible side passage on this property has several constraints:
- a wooden deck or staircase on the left;
- a brick wall along its entire length;
- a concrete structure directly to the right of the unit;
- a fence restricting access to the back of the property;
- ground covered with stone, vegetation, and seasonal debris;
- visible snow at the foot of the building.
Installing the unit on a ground slab would have increased the risk of winter obstruction and reduced the space available for moving around or maintaining the property. We therefore opted for a wall-mounted installation on metal supports.
This configuration offers several concrete advantages:
- The unit remains above small accumulations of snow.
- The metal base is not in contact with damp ground.
- Access to the refrigerant connections remains more convenient.
- Defrost cycles can take place with less risk of immediate accumulation beneath the chassis.
- The passage remains more open than it would be with a bulky base installed on the ground.
The supports must be secured to a structure capable of bearing the weight and vibrations of the unit. They must also keep the unit level to promote proper drainage during defrost cycles.
Discreet management of the piping on the brick wall
A multi-zone installation requires two separate refrigerant circuits between the outdoor unit and the indoor units. Each circuit normally includes a liquid line, a gas line, a communication cable, and a condensate drain associated with the indoor unit.
In this Châteauguay project, the lines were grouped together and protected in a light-colored vertical line cover installed on the brick wall. Choosing a shade close to the existing architectural elements helps reduce the installation’s visual impact.
The line cover is not used solely to conceal the lines. It also helps protect:
- the pipe insulation against ultraviolet rays;
- the cables against the elements;
- the lines against accidental impacts;
- the connections against damage caused by animals;
- the overall appearance of the side façade.
When an outdoor refrigerant line is left without adequate protection, its insulation can crack, retain water, or gradually lose its properties. A clean finish is therefore part of the installation’s technical durability, not merely its appearance.
Features of the HITACHI airHome Multi range
The HITACHI airHome Multi range is available with outdoor units from 18,000 to 42,000 BTU/h that can power two to five indoor units. The two-connection configuration corresponds to the RAM-G18N2HAA outdoor model presented in the manufacturer’s documentation.
In a ductless configuration, this model features, among other things:
- a nominal cooling capacity of 18,000 BTU/h;
- a nominal heating capacity of 22,000 BTU/h;
- a variable cooling capacity from 7,000 to 20,500 BTU/h;
- seasonal efficiency of up to 23.0 TRÉS2;
- a CPSC2 of up to 10.0 in Region 4 and 7.85 in Region 5;
- a heating range down to -20 °C;
- a refrigerant R32;
- a stated outdoor sound level of 52 dB(A);
- two 1/4-inch refrigerant connections for liquid and 3/8-inch connections for gas.
The documentation also indicates a minimum circuit ampacity of 16 A and maximum overcurrent protection of 25 A for the dual-zone outdoor model. The final electrical selection must nevertheless comply with the nameplate of the installed equipment, the manufacturer’s instructions, and the requirements applicable to the building.
The photograph does not allow the nameplate to be read or the exact capacity of the two indoor units to be confirmed. We therefore avoid arbitrarily assigning a BTU combination. The actual selection must always be based on an analysis of the floor areas, insulation, solar exposure, number of windows, ceiling height, and the specific needs of each zone.
Several compatible indoor unit formats
An important advantage of airHome Multi is the ability to combine different types of indoor units according to the building’s layout.
airHome 400 and airHome 650 wall-mounted units
Wall-mounted units are often chosen for bedrooms, living rooms, and living spaces. They require relatively little work and offer capacities ranging from 7,000 to 24,000 BTU/h, depending on the series and model.
The airHome 650 series can include a motion detector designed to reduce consumption when the room is unoccupied.
airHome Floor console
The console can be installed near the floor, mounted on the wall, or placed on its base. It is a practical option when a high wall-mounted unit cannot be installed because of large windows, a sloped ceiling, or limited wall space.
Four-way mini cassette
The mini cassette distributes air in four directions. Its compact format is designed to fit into standard ceiling structures. It may be suitable for a central area where more uniform air distribution is desired.
Concealed ducted unit
A small ducted unit can supply one or more grilles while remaining concealed. This solution better preserves the interior appearance, but requires space for ducts, service access, and return air.
Air quality and coil maintenance
Some indoor units compatible with the airHome Multi range include FrostWash technology. It uses a freezing and thawing process designed to loosen contaminants accumulated on the heat exchanger coil.
The Mold Guard function helps dry the internal components after a period of cooling or dehumidification. This step can reduce conditions that promote odors and mold growth inside the unit.
Depending on the type of indoor unit, the system may also be equipped with a PM2.5 activated carbon filter or a ViroSense S filter. These features do not replace regular HVAC maintenance. The filters must be inspected and cleaned, while more thorough cleaning remains necessary when dust accumulates on the blower wheel, drain pan, or heat exchanger.
An installation suited to Châteauguay winters
The manufacturer states that the airHome Multi can continue operating in heating mode down to an outdoor temperature of -20 °C. However, the minimum operating temperature must be distinguished from the capacity actually available.
For the RAM-G18N2HAA dual-zone model, the documentation indicates a maximum heating capacity of approximately:
- 14,300 BTU/h at -15 °C;
- 9,700 BTU/h at -20 °C.
This means that the heat pump continues to produce heat in cold weather, but its capacity decreases as the outdoor temperature drops. For this reason, we always assess the presence and capacity of a backup heating system before recommending a heat pump as the sole source of heating.
In many homes in Châteauguay, the existing heating system can be retained for periods of intense cold. The heat pump then handles a large portion of the annual heating needs, while the backup system takes over when demand exceeds its available capacity.
The importance of clearances around the outdoor unit
The location shown in the photo is compact. This type of situation requires a careful check of the clearances specified by the manufacturer.
In particular, the following must remain clear:
- the air intake at the rear and on the sides;
- the air outlet in front of the fan;
- access to the service panels;
- sufficient clearance from obstacles that could cause discharged air to recirculate;
- a drainage area beneath the unit;
- safe access for future maintenance.
The concrete structure on the right must not obstruct access to the connection or create a pocket where snow and ice could accumulate against the frame. Likewise, the wooden staircase must not block airflow or transmit vibrations to the occupants.
A poorly positioned outdoor unit can recirculate its own cold air in winter or its hot air in summer. This recirculation increases operating pressures, reduces efficiency, and may accelerate compressor wear.
Mistakes to avoid with a multi-zone heat pump
Choosing capacity by simply adding up the floor area
Two rooms of the same size can have very different requirements. A north-facing bedroom with a small window does not perform like a south-facing living room with a patio door.
Oversizing each indoor unit
Adding two indoor units whose combined capacity greatly exceeds the actual requirements can cause short cycling, uneven temperatures, and less effective dehumidification.
Neglecting the minimum piping length
The technical specifications indicate a minimum total piping length of 16 ft for the dual-zone outdoor unit. The lengths, elevation differences, and refrigerant charge must be verified before commissioning.
Installing the unit too close to the ground
In Châteauguay and the Greater Montreal area, an installation that is too low can quickly be affected by compacted snow, ice from defrosting, or snowblower spray.
Forgetting about service access
A location may seem unobtrusive during installation but become problematic when it is time to measure pressures, replace an electronic control board, or clean the outdoor heat exchanger.
A dual-zone heat pump installed with a long-term perspective
This HITACHI airHome Multi multi-zone heat pump installation in Châteauguay shows that a narrow side passage can accommodate a clean, accessible, and protected system when every detail is carefully planned.
The elevated outdoor unit, the lines grouped inside a line-hide cover, the choice of a dual-zone system, and consideration of the immediate surroundings form a coherent whole. The result makes it possible to serve two areas of the home without installing two separate outdoor units.
At AirGreen, we analyze both the equipment’s performance and the realities of the building: indoor unit placement, piping routes, drainage, electrical supply, snow accumulation, vibrations, service access, and the final appearance. This approach applies to our installations in Châteauguay, Montréal, Laval, Longueuil, on the South Shore and the North Shore.
A well-chosen multi-zone heat pump is not defined solely by the number of BTUs listed on a quote. It must provide the right capacity for each room, logical air distribution, and an outdoor installation capable of withstanding Quebec’s seasons without compromising its operation.
The job tools
Two quick checks with real numbers: what heat costs, and what your current heaters add up to in BTU/h.
Conversion: 1 W = 3.412 BTU/h. An indication, not a load calculation: baseboards and furnaces are often stronger than the real need, and they can stay as backup. AirGreen confirms the capacity on site.
How the job unfolds
The main steps of this kind of job at AirGreen. Every house has its quirks: the estimate brings them out.
We look at the room, the outside wall, the line route and where the outdoor unit will go. That is where the capacity gets chosen.
Model, capacity and price, in writing. We also check whether the model qualifies for assistance programs.
Floors and furniture protected, wall plate position marked level, wall opening located.
A single opening, with the slope the drain needs to flow outside.
Set on a stand raised above the snow, with the clearances the manufacturer requires.
Connected, insulated and protected. The opening is then sealed against water, cold air and insects.
A dedicated circuit and an accessible disconnect near the outdoor unit.
Leak test, vacuum, then start-up and a check of heating and cooling.
Remote, modes, filters: we show you the essentials before we leave.
- The on-site estimateWe look at the room, the outside wall, the line route and where the outdoor unit will go. That is where the capacity gets chosen.
- The quoteModel, capacity and price, in writing. We also check whether the model qualifies for assistance programs.
- Getting readyFloors and furniture protected, wall plate position marked level, wall opening located.
- The wall openingA single opening, with the slope the drain needs to flow outside.
- The outdoor unitSet on a stand raised above the snow, with the clearances the manufacturer requires.
- Lines, cable and drainConnected, insulated and protected. The opening is then sealed against water, cold air and insects.
- The electrical workA dedicated circuit and an accessible disconnect near the outdoor unit.
- Tests and start-upLeak test, vacuum, then start-up and a check of heating and cooling.
- The walkthroughRemote, modes, filters: we show you the essentials before we leave.
What we check on a job like this one
Each number is a point we check on site. Switch between summer and winter to watch air and heat move.
In summer, the outdoor unit rejects the house's heat outside.
Generic illustration of this type of installation, not a survey of this job site. Tap a number.
Mounted level on a wall plate, high enough for the air to reach the whole room, with enough space around it to slide the filters out easily.
The refrigerant lines, the communication cable and the drain go through the wall in a single opening, sealed against water, cold air and insects.
Two insulated copper pipes connect the two units. Outside, a line cover can protect them from sun, knocks and weather.
A shut-off switch near the outdoor unit isolates it safely for service. It must stay accessible at all times.
The compressor and the fan. In heating mode it captures heat from the outdoor air, even in winter, and moves it inside.
On the ground or on the wall, it keeps the unit above accumulated snow. The unit stays clear and defrost water can drain away.
The fan needs to blow freely. Storage, a fence or a wall too close, and efficiency drops while noise goes up.
Is your home ready?
Check what applies at your place. A "no" is not a refusal: it is what we sort out during the estimate.
Good habits, once the unit is in place
Six simple habits that keep the unit going. Your list stays on this device.
What to do, season by season
Three habits per season for this unit. They take a few minutes and prevent many calls.
- Clean the indoor unit's filters.
- Clear leaves and debris left on the outdoor unit by winter.
- Test cooling before the first hot days.
- Clean the filters more often when the unit runs a lot.
- Keep plants away from the outdoor unit.
- Check that no water drips from the indoor unit.
- Rake the leaves around the outdoor unit.
- Test heating before the first cold days.
- Book periodic maintenance before winter.
- Keep snow away from the stand and the front of the unit.
- Let the unit defrost: it is normal.
- Never hit the ice on the fins; call us if the unit stays iced up.
The right pages, at the right time
Four statements: true or false?
It all comes down to details you have just seen.
1. In heating mode, the outdoor unit can produce water.
During defrost cycles. That water must drain away without forming ice.
2. You pick the capacity with a simple square-footage rule.
Windows, insulation, orientation and how the room is used all count. Capacity is chosen on site.
3. A multi-zone connects several indoor heads to a single condenser.
One head per room, all on the same condenser. Each room keeps its own temperature.
4. The disconnect can sit behind the patio furniture.
It must stay accessible: it is what shuts the unit off for service.
0 / 4 right answers
What people ask us about this kind of work
Does a wall-mounted heat pump heat in winter?
Wall-mounted or multi-zone: how do I choose?
Where does the outdoor unit go?
Are there grants?
Do I need a permit?
How cold can it heat?
How much can I save?
How is the LogisVert assistance calculated?
Is it noisy?
The outdoor unit is covered in ice: is that normal?
Does AirGreen hold the required licences?
Is the estimate free?
No question matches. Write to us: we answer.
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Text and photo: a real AirGreen Climatisation & Chauffage job. The diagrams are generic illustrations of the type of installation, not a survey of this job site. Sources of the added figures: airgreen.ca product pages (NEEP / AHRI performance), Hydro-Québec (Heat pumps page, LogisVert, read on 13 October 2026), Régie de l’énergie (rate D as of 1 April 2026).