Installation of a HITACHI airHome Multi dual-zone multizone heat pump in Fabreville, Laval

A precise wall-mounted installation in a narrow, landscaped side passage

In Fabreville, in western Laval, we installed a HITACHI airHome Multi dual-zone multi-zone heat pump to meet two distinct comfort needs with a single outdoor unit. The project involved a very practical constraint: the unit had to be integrated into a relatively narrow side passage between the house foundation, a wooden walkway, and well-established vegetation.

In this type of environment, installation involves more than simply mounting a heat pump on the wall. Every detail must be planned: equipment height, clearance in front of the fan, access to the refrigerant connections, line protection, management of defrost water, maintenance access, and preservation of the existing features around the house.

The photo taken during the work clearly shows this technical stage. The HITACHI airHome outdoor unit is already installed on wall brackets anchored to the foundation. The connections are still accessible on the right side, and our technician is working on installing the insulated refrigerant lines. The finishing pieces temporarily placed on top of the unit indicate that the installation was still in progress when the photo was taken.

This image mainly helps illustrate a reality of the trade: a professional HVAC installation is completed in stages. We first position the equipment precisely, make the mechanical and electrical connections, check the circuit for leaks, and then install the protective components and finishing elements.

Why a dual-zone heat pump was the right choice for this Fabreville property

A dual-zone multi-zone heat pump connects two indoor units to a single outdoor unit. The two zones can therefore be controlled separately, each with its own setpoint temperature and fan speed.

This configuration is particularly well suited to properties where two areas have different heating and cooling needs, for example:

• an open ground floor and a bedroom upstairs;
• a living room exposed to the sun and a room on the shaded side;
• an addition that remains colder than the original building;
• two floors whose temperatures are difficult to balance;
• a home office used on a different schedule;
• a primary bedroom that requires quieter operation at night.

In a Fabreville home, temperature differences between levels can become significant. Heat naturally rises, large windows increase solar gains, and some rooms may be farther from the existing heating system. A dual-zone configuration can then directly address the problem areas without installing two separate outdoor units.

The HITACHI airHome Multi system allows individual control of the indoor units. One zone can be turned off while the other continues to operate. Temperature and fan settings can also be adjusted independently for each room. However, the overall mode remains common to the entire system: in summer, the units can operate in cooling, dehumidification, or fan mode; in winter, they operate in heating or fan mode.

This distinction is important. A multizone heat pump normally cannot actively heat one room while cooling another with the same outdoor unit. We explain this feature to homeowners before installation so that the system’s actual operation matches their expectations.

Wall-mounted positioning suited to the constraints of the side passageway

The outdoor unit was mounted on the foundation using independent metal supports. This solution offered several advantages for this Fabreville property.

First, it made it possible to preserve the ground surface. The passageway has wooden boards and dense vegetation, leaving little room for a concrete slab or a traditional raised base. A wall-mounted support also avoids placing the unit directly in the middle of the passageway.

Next, mounting the heat pump on the foundation keeps its bottom above the ground. This height is useful during winter because it reduces the risks associated with snow accumulation, wet leaves, and ice produced by defrost cycles.

The visible supports beneath the unit include anti-vibration components. These help limit the transmission of mechanical vibrations to the structure. Their effectiveness nevertheless depends on several factors: anchor quality, foundation rigidity, unit leveling, and uniform load distribution.

We must also avoid attaching the equipment to a lightweight exterior cladding that does not have the required strength. On this project, the anchors are installed in the solid part of the foundation, beneath the house cladding.

Vegetation: an aesthetic detail that becomes a technical constraint

The climbing plants and vegetation on the left side of the passage provide privacy and contribute to the landscaping. However, they must be controlled around a heat pump.

Leaves, stems, and plant debris can gradually move closer to the outdoor heat exchanger. They may then:

• reducing air intake;
• accumulating on the coil;
• holding moisture against the cabinet;
• increasing the frequency of cleaning;
• obstructing access to the service panel;
• being drawn into the fan.

In the photo, the front fan remains unobstructed. The area in front of the unit must remain clear so that air can be expelled without immediately encountering an obstacle. We recommend that the owner regularly trim the vegetation and remove leaves that accumulate under or behind the unit.

The outdoor unit should also not be used as a support for climbing plants. A vine may seem lightweight at first, but it can quickly reach the grille, panels, or connections.

Carefully prepared refrigerant lines

The right side of the outdoor unit shows the service connections and copper lines being installed. In a dual-zone system, two refrigerant circuits connect the outdoor unit to the two indoor units.

Each circuit generally includes:

• a liquid line;
• a gas line;
• a communication and power cable;
• a condensate drain from the indoor unit.

The lines must be properly insulated to reduce heat loss and prevent condensation. They must also be bent without kinking. A bend that is too tight can deform the copper, reduce the inside diameter, and impair refrigerant flow.

The step shown in the photo normally precedes the complete finishing of the route. Once the connections have been checked, the lines and cables can be grouped inside an outdoor line set cover. This cover protects the materials from ultraviolet rays, the weather, and accidental damage while improving the installation’s overall appearance.

Why evacuation and leak testing are essential

After the lines are connected, the system must not be started immediately. We must first perform the necessary procedures to confirm its integrity.

Proper installation includes, among other things:

1. checking the connections;
2. leak testing according to the applicable procedure;
3. evacuating the circuit;
4. confirming that the vacuum is holding;
5. opening the service valves;
6. starting the system and checking the temperatures;
7. checking the drains and controls.

The vacuum-pumping process removes the air and moisture present in the lines. Residual moisture can contaminate the compressor oil, affect the refrigerant, and reduce long-term reliability. This step is invisible once the installation is complete, but it is one of the most important operations in any wall-mounted air conditioner or multi-zone heat pump project.

The performance and features of HITACHI airHome Multi

The HITACHI airHome Multi range consists of multi-zone systems equipped with Inverter technology and using R32 refrigerant. Depending on the outdoor model, it can connect two to five indoor units and offers rated cooling capacities ranging from 18,000 to 42,000 BTU/h.

The photo does not allow the exact model number of the installed unit to be read. In the HITACHI documentation provided, the outdoor platform designed for two indoor connections is the RAM-G18N2HAA. It has a rated cooling capacity of 18,000 BTU/h and a rated heating capacity of 22,000 BTU/h.

The choice of indoor units and their combination must nevertheless be validated using the manufacturer’s technical tables. It is not enough to add together the capacities of two wall-mounted units and assume that the outdoor unit will constantly provide the resulting total. The available capacity is modulated and distributed among the zones according to demand.

Energy data suited to four-season use

For the ductless configuration of the dual-zone model presented in the brochure, the published performance can reach:

• a TRÉS2 of 23.0;
• a CPSC2 of 10.0 in Region 4;
• a CPSC2 of 7.85 in Region 5;
• a rated heating capacity of 22,000 BTU/h;
• a maximum heating capacity of 14,300 BTU/h at -15 °C;
• a maximum heating capacity of 9,700 BTU/h at -20 °C.

The system is designed to operate in heating mode down to an outdoor temperature of -20 °C.

These figures must be interpreted correctly. A heat pump’s capacity generally decreases as the outdoor temperature drops. A rated capacity measured under moderate conditions therefore does not necessarily represent the available output during a very cold night in Laval.

At AirGreen, we analyze the intended role of the heat pump:

• primary heating for much of the year;
• supplement to an existing electric system;
• improved comfort in two specific areas;
• replacement of window air conditioners;
• reduced use of electric baseboard heaters;
• summer air conditioning and dehumidification.

This analysis determines whether the heat pump can meet the needs of the zones on its own or whether the existing heating system must remain available as backup.

A relatively compact outdoor unit

According to the technical specifications, the RAM-G18N2HAA dual-zone model measures approximately 33.5 in wide, 29.5 in high, and 11.7 in deep. Its net weight is approximately 108 lb. The outdoor sound level advertised at high speed is 52 dB(A).

These dimensions explain why this unit can be installed in a side passage like the one shown in the photograph, provided the necessary clearances are respected. Its shallow depth makes positioning against the foundation easier, but it does not eliminate the need to assess airflow.

The front fan must have a clear area. The sides and rear must also meet the manufacturer's installation requirements to allow air intake, technical access, and heat dissipation.

Indoor units adapted to the needs of each zone

One of the advantages of the airHome Multi range is the ability to combine several types of compatible indoor units. HITACHI documentation specifically presents:

• airHome 400, a wall-mounted unit focused on essential features;
• airHome 650, a wall-mounted unit with additional smart features;
• airHome Floor, a console that can be installed near the floor;
• airHome Mini Cassette, integrated into the ceiling with four-way air distribution;
• airHome Ducted, concealed in a utility space and connected to short ducts.

Available indoor capacities generally range from 7,000 to 24,000 BTU/h, depending on the unit type.

In a dual-zone configuration, we can therefore adapt air distribution to the architecture of each room. A wall-mounted unit may suit the living room, while a floor console may be better suited to a room with limited wall space.

Indoor unit filtration and maintenance

Depending on the indoor units selected, the system may include a PM2.5 activated carbon filter or a ViroSense S filter. FrostWash technology uses a freezing and thawing process to help clean the indoor coil. The Mold Guard function circulates air for approximately 60 minutes after a cooling or dehumidification operation to dry the internal components.

These features make it easier to manage humidity and buildup, but they do not replace HVAC maintenance. Filters must be cleaned periodically. The blower wheel, coil, condensate pan, and drain should also be inspected when odors, reduced airflow, or abnormal drainage occur.

In a house surrounded by vegetation, such as the one in this Fabreville project, exterior maintenance is just as important. The coil of the outdoor unit can accumulate pollen, seeds, dust, and small plant debris.

R32 leak sensor and smart features

Compatible indoor units include a sensor designed to alert occupants in the event of an R32 refrigerant leak. Depending on the model and accessories, the alert may take the form of an indicator light, an audible alarm, or an indication on a compatible wall controller.

A airCloud Go Wi-Fi interface can also be added. It allows you to control the system remotely, schedule operating periods, and monitor certain usage data.

Some units, particularly in the airHome 650 range, may include a motion detector. The Smart Eco function then reduces power when the room is unoccupied, while automatic shutoff can deactivate the unit after a predetermined period.

Piping lengths to follow

Piping length is a decisive factor in a multi-zone project. For the dual-zone model in the brochure, HITACHI specifies:

• a maximum total piping length of 165 feet;
• a maximum length of 82 feet between the outdoor unit and an indoor unit;
• a minimum length of 16 feet;
• a maximum total height of 66 feet;
• a maximum elevation difference of 16 feet between the indoor units.

The two outdoor connections use 1/4-inch liquid lines and 3/8-inch gas lines.

These limitations influence the choice of the outdoor location. Placing the unit in a well-positioned side passageway can reduce the amount of copper piping, simplify the routing, and limit losses. Conversely, a location chosen solely for aesthetic reasons can result in unnecessarily long lines or routing that is difficult to maintain.

Mistakes to avoid in a narrow passageway

An installation similar to the one in Fabreville requires several checks. Among the most common mistakes are:

Install the unit too close to vegetation

Vegetation must remain far enough away so as not to obstruct the heat exchanger and fan.

Install the unit too low

A heat pump used for heating must be protected from snow, ice, leaves, and defrost water.

Neglect passageway circulation

The unit must not create a dangerous obstruction or excessively reduce access to the side of the property.

Place the fan too close to a wall

Discharged air must be able to disperse. A frontal obstruction can cause recirculation and reduce efficiency.

Forget access to the service panel

The connections, valves, and electrical compartment must remain accessible for HVAC maintenance and repairs.

Leave the refrigeration insulation exposed

Unprotected insulation deteriorates quickly under exposure to UV rays, weather, and animals.

Choose capacities without calculating the needs of each zone

Two rooms of similar dimensions can have very different loads depending on the insulation, glazing, orientation, and floor.

An electrical supply to be verified according to the installed model

The RAM-G18N2HAA dual-zone model presented in the documentation operates on a 208–230 V, single-phase, 60 Hz power supply. Its technical sheet specifies a minimum circuit ampacity of 16 A and maximum overcurrent protection of 25 A.

These values serve as a reference for this specific platform. On site, we must always verify the nameplate of the installed unit, the conductor gauge, the disconnecting means, and the requirements applicable to electrical work.

BTU capacity alone is not enough to choose a circuit breaker. The MCA and MOP values provided by the manufacturer should guide the electrical selection.

An installation designed to remain accessible

Positioning the unit on wall brackets leaves space beneath the appliance. This configuration makes it easier to remove leaves and clean the area. It also makes it possible to quickly see whether ice or water is accumulating beneath the heat pump.

The right side, where the connections are located, remains accessible during the work. Once finishing is complete, the line-hide cover must be installed without blocking the service panels.

This accessibility can reduce the time required for future service. A heat pump wedged between a wall, a fence, and overly dense vegetation becomes much more difficult to maintain.

The goal: two comfortable zones with a single outdoor unit

This HITACHI airHome Multi multi-zone heat pump installation in Fabreville serves two spaces without adding multiple outdoor units around the property. The wall-mounted installation preserves ground clearance, protects the unit from seasonal accumulation, and makes efficient use of the solid part of the foundation.

The success of this project relies on several coordinated decisions:

• selection of a dual-zone platform;
• positioning in a restricted side space;
• anchoring on wall brackets;
• fan clearance;
• maintaining access to the connections;
• careful preparation of the lines;
• future protection of the refrigerant line route;
• consideration of the existing vegetation.

At AirGreen, we apply this same approach to multi-zone heat pump, wall-mounted air conditioner, central system, and HVAC installation projects in Fabreville, Laval, Montreal, Longueuil, the North Shore, and the South Shore. The heat pump model is important, but the quality of the result depends just as much on its sizing, location, and the execution of the work.