Two comfort zones brought together in a discreet, carefully integrated indoor installation
In Duvernay, in eastern Laval, we installed a HITACHI airHome Multi dual-zone multi-zone heat pump to cool and heat two separate spaces using a single outdoor unit. The project required particularly careful integration into the residence’s interior: the walls featured a vertical textured finish, the ceiling consisted of decorative panels, and crown molding bordered the upper part of the room.
In this context, the location of the wall-mounted unit could not be chosen solely based on the shortest distance to the outdoors. We had to consider the room’s appearance, air distribution, the clearance required around the unit, access to the filters, and the routing of the refrigerant lines.
The photograph of this project shows a HITACHI indoor unit installed in the upper part of the wall. Its white casing blends naturally into the light-colored decor, while the absence of visible ducting on the section of wall shown helps preserve a clean, understated finish. The air outlet flap remains completely unobstructed, allowing conditioned air to be directed toward the occupied area rather than against molding, furniture, or an architectural obstacle.
This type of result requires precise preparation. A successful HVAC installation involves more than simply mounting a wall-mounted air conditioner and connecting two pipes. We must consider how air will circulate through the room, where condensate will be drained, and how the equipment can be serviced several years after installation.
Why a dual-zone configuration was suitable for this Duvernay property
A multi-zone heat pump is designed to power multiple indoor units with a single outdoor unit. In this residence, the dual-zone configuration makes it possible to condition two separate spaces that do not necessarily have the same requirements.
The temperature of a room varies according to several factors:
- its area and ceiling height;
- its orientation in relation to the sun;
- the quantity and type of glazing;
- the level of insulation;
- the presence of a kitchen or heat-generating appliances;
- the number of occupants;
- the frequency of use of the room;
- natural airflow between floors.
A single wall-mounted head placed in a hallway or common area cannot always distribute comfort evenly to rooms separated by doors. Instead, the dual-zone system makes it possible to install an indoor unit in each priority area.
Each HITACHI unit can be set to its own setpoint and fan speed. One zone can also be turned off while the other remains active. This flexibility is particularly useful in a home where a bedroom, office, basement, or family room is occupied on a different schedule.
Nevertheless, the operating principle common to multizone systems must be followed: indoor units connected to the same outdoor unit must operate in compatible modes. During the summer, the heads can be used for cooling, dehumidification, or ventilation. During the winter, they can operate in heating or ventilation mode. It is not possible to request heating in one zone and cooling in another at the same time.
The HITACHI brochure specifies that an airHome Multi outdoor unit can power up to five indoor units, depending on the model selected, and that each can be controlled individually. It also presents several compatible formats, including airHome 400 and airHome 650 wall-mounted units, floor consoles, mini-cassettes, and ducted units.
Choosing the indoor unit’s location
The unit shown in the photo is installed near the ceiling on an unobstructed wall. This position promotes efficient air distribution because the unit can direct airflow into the room without being blocked by a tall piece of furniture or a bookcase.
Working around the trim and decorative ceiling
Architectural features can make installation more complex than it may appear. In this room, the upper trim and ceiling panels reduce the space available above the unit. We therefore need to position the mounting plate precisely to maintain the required clearances and keep the unit perfectly level.
A tilted unit or one installed against trim can cause several problems:
- difficulty removing the filters;
- cabinet vibrations;
- poor condensate drainage;
- restricted access to the service panel;
- reduced airflow;
- uneven visual finish.
We also inspect the structure behind the wall covering. The mounting plate must be securely fastened to support the unit and prevent normal fan vibrations from being transmitted to the wall.
Preserving the wall’s appearance
The vertical textured cladding quickly draws attention to a poorly aligned line set cover, an opening that is too large, or an approximate finishing repair. In the visible area of the photo, no exterior piping descends below the wall-mounted head. The installation therefore retains a clean appearance, with a unit centered in an unobstructed section of the wall.
When the building structure allows it, the lines can be routed directly behind the unit or through a suitable cavity. When this route is not possible, we plan a line set cover whose color, path, and angles blend as well as possible with the room.
The goal is never to conceal the lines at the expense of their accessibility or slope. Drainage must remain functional, and the refrigerant lines must not be crushed in a passage that is too tight.
A wall-mounted unit designed for everyday comfort
The indoor units compatible with the HITACHI airHome Multi range are available in several capacities, from 7,000 to 24,000 BTU/h for the wall-mounted models shown in the documentation. The exact capacity of the photographed unit cannot be confirmed from its appearance alone. It must be verified on the rating plate or in the project documents.
This precision is important because two units of similar size can have very different capacities. The choice should not be based solely on the width of the casing or the approximate area of the room.
At AirGreen, we consider in particular:
- the cooling load;
- the heating load;
- the capacity available at low temperatures;
- the required airflow;
- the desired sound level;
- the combination authorized by the manufacturer;
- the total capacity of the outdoor unit.
An oversized head can cause short cycles and less consistent dehumidification. An undersized head may operate continuously at high speed without reaching the requested temperature during extreme conditions.
The Inverter operation of the HITACHI airHome Multi system
Inverter technology allows the compressor to adjust its speed according to the zones’ actual demand. Instead of operating only at full capacity and then stopping, the system can modulate its output.
This modulation provides several concrete benefits:
- more stable indoor temperature;
- fewer abrupt starts;
- quieter operation at partial load;
- better adaptation when only one zone is active;
- consumption better matched to actual needs.
In a dual-zone configuration, modulation is particularly useful. When both spaces require substantial heating or cooling, the outdoor unit increases its output. When one zone reaches its setpoint, the system reduces its capacity and redistributes it according to the remaining demand.
The performance of the airHome Multi range
The HITACHI airHome Multi family includes outdoor units from 18,000 to 42,000 BTU/h. For a configuration limited to two indoor connections, the documentation presents the outdoor model RAM-G18N2HAA.
In a ductless configuration, its published specifications include, among others:
- nominal cooling capacity of 18,000 BTU/h;
- cooling modulation from 7,000 to 20,500 BTU/h;
- nominal heating capacity of 22,000 BTU/h;
- heating modulation from 9,000 to 24,000 BTU/h;
- TRÉS2 that can reach 23,0;
- CPSC2 for region 5 that can reach 7,85;
- heating operation down to -20 °C;
- cooling operation from -10 °C to 46 °C;
- refrigerant R32;
- announced outdoor sound level of 52 dB(A).
These data vary depending on the exact combination of indoor units. They therefore do not replace the AHRI certificate corresponding to the system actually installed.
Cold-weather capacity must be analyzed separately
A heat pump does not necessarily retain its full nominal capacity as the outdoor temperature drops. According to the HITACHI technical table, the RAM-G18N2HAA model can provide a maximum heating capacity of approximately 14,300 BTU/h at -15 °C and 9,700 BTU/h at -20 °C.
This information is essential in an area such as Duvernay, where winter temperatures can be very low. Sizing must account for the capacity available at design temperatures, not just the nominal value indicated in the system name.
Depending on the building’s characteristics, the heat pump can be used as the primary source for much of the winter, with a backup system available during colder periods.
The invisible details that determine the quality of a multi-zone installation
Condensate drainage
In cooling mode, moisture removed from the air turns into water on the indoor coil. This water must be drained continuously.
We pay particular attention to:
- drain slope;
- pipe fastening;
- the absence of backslopes;
- protection against blockages;
- the water’s final destination;
- the seal around the wall penetration.
An improper slope can cause water to back up into the drain pan, water noises, or an indoor leak. When gravity drainage is not possible, a condensate pump may be required. It must then be selected and installed to limit noise in the room.
The refrigerant fittings for each zone
A dual-zone system has two piping circuits connecting the outdoor unit to the indoor units. For the RAM-G18N2HAA model, the documentation specifies two liquid fittings 1/4 po and two gas fittings 3/8 po.
Each circuit must be properly identified. The communication wiring for zone A must correspond to the refrigerant lines for that same zone. A mix-up can cause inconsistent operation or an error during commissioning.
The essential steps include:
- cleanly cutting the copper pipes;
- deburring without contamination;
- making the flares;
- tightening to the appropriate torque;
- the leak test;
- evacuation;
- verifying the charge based on the installed lengths.
The brochure specifies, for the dual-zone model, a maximum total piping length of 165 feet, a maximum length of 82 feet between the outdoor unit and an indoor unit, and a minimum length of 16 feet. These limits must be incorporated into the planning before work begins.
Commissioning the two zones
After the mechanical installation, we test each unit separately and then verify the simultaneous operation of both zones.
Our inspection includes, in particular:
- the startup of each unit;
- the correspondence between the circuits and controls;
- drain flow;
- return-air and supply-air temperatures;
- fan speeds;
- cabinet vibrations;
- the operation of the louvers;
- the response to setpoint changes;
- the absence of error codes;
- explaining the modes to the owner.
This step also reminds occupants that both units must be set to the same seasonal mode. One head set to heating and the other to cooling may prevent the system from responding properly.
Maintenance and air-quality functions
Depending on the selected indoor model, the HITACHI range offers several functions designed to simplify maintenance and limit the accumulation of contaminants.
FrostWash
The FrostWash function uses a freezing and thawing process to clean the indoor heat exchanger coil. Freezing traps some of the dust and contaminants, which are then removed during thawing.
This function does not replace periodic maintenance. The filters must still be cleaned, and the fan, drain pan, and coil must be inspected according to the unit’s usage.
Mold Guard
After a period of cooling or dehumidification, the Mold Guard function helps dry the internal components for approximately 60 minutes. This sequence is intended to reduce residual moisture that can contribute to odors and mold growth.
Filtration
The wall-mounted units shown in the brochure may include a PM2.5 activated carbon filter. However, the filtration level and available accessories depend on the selected indoor model. It is therefore important to consult the exact specification sheet rather than assume that all units have the same components.
Common mistakes to avoid
Installing the indoor unit too close to the ceiling
The unit must maintain the clearance required by the manufacturer. Insufficient space can restrict air intake and make it difficult to open the front panel.
Directing the airflow toward the bed or sofa
A properly sized unit can become uncomfortable if its air is directed straight at occupants. We consider the position of furniture, doors and resting areas before mounting the plate.
Choosing two capacities without calculating the actual demand
The sum of the nominal capacities of the indoor units does not always represent the capacity available simultaneously. The manufacturer's combination rules and the outdoor unit's behavior must be verified.
Neglecting filter cleaning
A clogged filter reduces airflow, increases noise and can decrease performance. During regular use, checking it monthly is a good habit, although the exact frequency depends on the presence of pets, dust and the number of occupants.
Completely closing off one room in the hope of cooling neighboring spaces
A wall-mounted unit primarily conditions the room where it is installed. Doors, corridors and differences in floor level limit the natural movement of air. This is precisely one of the reasons why a dual-zone configuration may be preferable.
An AirGreen installation designed for Duvernay and Greater Montreal
This Duvernay installation demonstrates that a HITACHI airHome Multi multizone heat pump can be discreetly integrated into a room with pronounced architectural details. The white casing blends in with the wall, the air outlet remains unobstructed and the unit is positioned to distribute air throughout the occupied area.
The quality of such an installation depends on several decisions made even before drilling into the wall: capacity selection, the location of each indoor unit, line-set routing, drainage, electrical supply, clearances and accessibility.
We apply this same approach to multizone heat pump projects in Laval, as well as in Montreal, Longueuil, on the North Shore and the South Shore. Each property presents its own constraints: brick walls, low ceilings, finished basements, condominiums, flat roofs, balconies or limited outdoor space.
In this Duvernay residence, the dual-zone configuration serves a clear purpose: providing more precise control of two areas of the home without multiplying the number of outdoor units. The HITACHI airHome Multi system offers the necessary flexibility, while the indoor installation maintains a visual finish suited to the existing decor.