Installation of a HITACHI airHome Multi triple-zone multi-zone heat pump in Saint-Vincent-de-Paul, Laval

A single outdoor unit to ensure the comfort of three distinct zones

This installation, carried out in Saint-Vincent-de-Paul, in eastern Laval, met a specific objective: heating and cooling three areas of the property without installing three separate outdoor units. We therefore selected a HITACHI airHome Multi triple-zone multi-zone heat pump, a configuration that connects up to three indoor units to a single outdoor unit.

The photograph shows a particularly meticulous outdoor installation. The HITACHI unit is placed on a raised aluminum structure, which is itself firmly anchored to a concrete slab. The three refrigerant lines are grouped in horizontal line-hide covers installed against the wall, while the electrical supply terminates at an outdoor disconnect switch located near the unit.

This type of project requires much more than simply mounting a heat pump. In a triple-zone installation, we must coordinate three refrigerant circuits, three condensate drains, three communication cables, the respective capacities of the indoor units, and the combination limits imposed by the manufacturer.

In Saint-Vincent-de-Paul, where many properties have multiple floors, additions, or rooms separated by hallways, a multi-zone system is often a more logical solution than a single wall-mounted unit installed in a central area.

Why choose a triple-zone heat pump?

A single-zone heat pump efficiently handles an open area when it is properly sized and positioned. However, it becomes less effective when air must pass through several doors, go up a staircase, or reach rooms that are far away.

A triple-zone system makes it possible to place an indoor unit directly in each of the priority areas. Depending on the layout of the residence, these three zones may correspond to:

• a main living area on the ground floor;
• an upstairs bedroom or set of bedrooms;
• a finished basement;
• a closed office;
• a home extension;
• a dwelling or section used according to a different schedule.

Each indoor unit has its own controller. Occupants can therefore individually adjust the temperature, fan speed, and several operating settings.

One unit can be turned off while the other two remain active. This flexibility helps limit unnecessary operation in a rarely used room and allows comfort to be adjusted to the occupants’ preferences.

However, it is important to understand one key rule: all units connected to the same outdoor unit must operate in a compatible mode. In summer, they use cooling, dehumidification, or ventilation. In winter, they operate in heating or ventilation mode. One indoor unit cannot cool while another is simultaneously requesting heating.

A HITACHI outdoor unit installed on an aluminum support

The most visible element of this installation is the raised base. The outdoor unit is not simply placed on the concrete slab: it rests on a metal support designed to keep it well above the ground.

In Laval’s climate, this choice offers several advantages.

Protection against snow accumulation

A heat pump must draw in and discharge a large amount of outdoor air. If snow reaches the bottom of the coil or blocks part of the openings, airflow decreases and performance may be affected.

Raising the unit helps keep the heat exchanger above typical accumulations and reduces the risk of snow moved around the house quickly reaching the chassis.

This protection remains complementary to regular snow removal. The owner must always keep a clear space around the unit and avoid piling snow from a shovel or snowblower against the appliance.

Better management of defrost water

In heating mode, frost periodically forms on the outdoor heat exchanger. The heat pump then initiates a defrost cycle that produces water.

An installation that is too low can lead to the formation of an ice block directly beneath the unit. This block may gradually reach the chassis base or interfere with drainage during subsequent cycles.

The structure visible in the photo leaves enough space beneath the unit for water to drain toward the slab. However, the condition of this area should still be monitored during freeze-thaw periods.

Maintaining clearance around the coil

The support places the unit at a height that also makes it easier to inspect its underside. Leaves, dirt, and plant debris are less likely to come into direct contact with the chassis.

A stable concrete slab independent of loose soil

The metal support is anchored to a rectangular concrete slab. This base helps keep the unit level and reduce movement caused by the ground.

A heat pump installed directly on improvised blocks, unstable slabs, or insufficiently compacted ground may shift during freezing and thawing. Even a relatively small movement can place stress on the refrigerant lines.

The slab in this project provides a level surface for all four feet of the stand. Each foot is secured separately, increasing the stability of the assembly.

The area around the slab contains soil, mulch, gravel, and plant debris. Creating a defined base clearly separates the equipment from this environment and facilitates maintenance around the installation.

A clean exterior finish despite three separate circuits

A three-zone installation necessarily has more lines than a single-zone system. Each indoor unit normally has:

• a liquid line;
• a gas line;
• a communication cable;
• a condensate drain;
• proper thermal insulation.

In this Saint-Vincent-de-Paul installation, the runs were grouped inside light-colored line-hide covers. Two parallel horizontal sections are visible on the wall, with a clean transition toward the side of the outdoor unit.

This arrangement protects the components while maintaining a structured appearance. Without line-hide covers, several separately secured insulated lines on a textured wall would have created a much busier finish.

Line-hide covers are used, among other things, to protect:

• the insulation from ultraviolet rays;
• the cables from the weather;
• the lines from impacts;
• the connections from animals;
• the property's exterior appearance.

The fasteners must be suitable for the building cladding and positioned to support the lines without crushing them.

The model associated with a three-zone configuration

In the HITACHI airHome Multi documentation, the outdoor model designed with three indoor connections is the RAM-G24N3HAA. Its published nominal capacity is 24,000 BTU/h for cooling and 24,000 BTU/h for heating.

The nameplate of the photographed unit is not visible. Therefore, we cannot confirm from the image alone that this unit bears exactly this model number. However, the RAM-G24N3HAA is the three-connection model presented in the supplied range.

For a ductless combination, its published key features include:

• 24,000 BTU/h nominal cooling capacity;
• a cooling range of 7,000 to 28,000 BTU/h;
• 24,000 BTU/h of rated heating capacity;
• a heating range of 9,000 to 26,200 BTU/h;
• efficiency of up to 22.0 TRÉS2;
• a CPSC2 of up to 9.5 in Region 4 and 7.8 in Region 5;
• a COP of 3.5 at 8 °C;
• a maximum heating capacity of 18,500 BTU/h at -15 °C;
• a maximum heating capacity of 13,000 BTU/h at -20 °C;
• heating operation down to -20 °C;
• a refrigerant R32;
• an advertised outdoor sound level of 54 dB(A).

The documentation also specifies a 208–230 V single-phase power supply, a minimum circuit ampacity of 19 A, and maximum overcurrent protection of 35 A for this model. The values on the nameplate of the installed equipment always take precedence during electrical work.

Three indoor units do not mean three identical capacities

In a multi-zone system, the capacity of each indoor unit must match the requirements of its room. It would be incorrect to automatically divide the outdoor unit's 24,000 BTU/h into three equal parts.

A large open-plan area may require a larger unit than a bedroom. A combination could therefore include different capacities, subject to configurations approved by HITACHI.

The airHome Multi range allows the use of several indoor unit formats:

• airHome 400 wall-mounted units;
• airHome 650 wall-mounted units;
• airHome Floor consoles;
• mini cassettes;
• concealed ducted units.

Wall-mounted and ducted units are available in various capacities, generally from 7,000 to 24,000 BTU/h depending on the series. The mini cassette covers capacities of up to 20,500 BTU/h, while the floor console is available up to 18,000 BTU/h.

The final combination must comply with the manufacturer's limits. We therefore check the total connected capacity, the permitted models, and the certified performance of the system as a whole before preparing the installation.

Inverter technology at the heart of multi-zone operation

Inverter technology allows the compressor to vary its speed according to demand. This modulation is particularly useful with three zones because requirements are constantly changing.

At certain times, all three indoor units may operate simultaneously. At other times, only one room requires heating or cooling. The compressor then adjusts its output within the limits of its operating range.

This modulation can help:

• maintain a more stable temperature;
• reduce repeated starts;
• limit noise when demand is low;
• adjust consumption to actual usage;
• improve comfort between cycles.

However, it is important not to assume that each indoor unit always has its full rated capacity available when all zones are operating simultaneously. The available capacity is shared by the outdoor unit according to the needs and operating conditions.

Winter performance in Laval: look at capacity, not just the minimum temperature

The brochure states that the HITACHI airHome Multi range can operate in heating mode down to -20°C. This confirms the operating limit, but it does not mean that the equipment maintains 24,000 BTU/h of heating capacity at that temperature.

For the ductless RAM-G24N3HAA, the published maximum capacity is approximately:

• 18,500 BTU/h at -15°C;
• 13,000 BTU/h at -20°C.

This decrease is normal for an air-source heat pump. The lower the outdoor temperature, the less readily recoverable energy the air contains.

Before recommending a triple-zone system in Saint-Vincent-de-Paul or elsewhere in Laval, we therefore assess:

• the building’s heat loss;
• the capacity required at the design temperature;
• the condition of the insulation;
• the presence of electric baseboards or other supplemental heating;
• the homeowner’s expectations;
• the desired indoor temperature;
• the distribution of heat among the three zones.

A properly sized heat pump can cover a large portion of annual heating needs, but supplemental heating may still be necessary during the coldest periods.

Piping lengths to follow in a triple-zone installation

The RAM-G24N3HAA outdoor unit has three 1/4-inch liquid connections and three 3/8-inch gas connections, according to the manufacturer’s documentation.

The published piping limits include:

• a maximum total length of 200 ft;
• a maximum total height of 66 ft;
• a maximum length of 82 ft between the units;
• a minimum total length of 16 ft;
• a maximum elevation difference of 16 ft between the indoor units.

These limitations explain why the outdoor unit’s location must be planned according to the three indoor units, rather than based solely on the most discreet spot outside.

A location that is too far away can increase the amount of piping, installation costs, and the need for additional refrigerant. A poor choice can also complicate gravity drainage of condensate.

The electrical disconnect switch installed nearby

In the photograph, a gray disconnect switch is installed to the right of the outdoor unit. This equipment allows the power supply to be interrupted locally during maintenance or repair work.

Its location must remain accessible to the technician without unnecessarily exposing it to the risk of electric shock or damage. Outdoor wiring must be protected and installed in accordance with applicable requirements.

The electrical-panel protection must never be selected solely based on BTU capacity. It must correspond to the MCA and MOP values listed on the nameplate and in the model documentation.

Air quality and functions offered by the indoor units

Depending on the type of indoor unit selected, the airHome Multi product line may include several functions intended for maintenance and air quality.

FrostWash

FrostWash technology uses a freezing and thawing cycle to help detach contaminants present on the indoor coil. It is designed to preserve heat transfer and airflow.

This function does not replace thorough mechanical cleaning when a blower wheel, drain pan, or heat exchanger is heavily soiled.

Mold Guard

After a period of cooling or dehumidification, the Mold Guard function circulates air for approximately 60 minutes to dry the internal components. This operation helps reduce residual moisture that could promote odors.

Filtration

Depending on the indoor model, the product line may use a PM2.5 activated carbon filter or a ViroSense S filter. The brochure also mentions functions designed to address fine particles, volatile organic compounds, and certain contaminants.

The exact availability of these functions must be confirmed for the installed indoor units. Not all product-line features are necessarily available on every model.

Leak sensor for R32 refrigerant

The product line uses R32 refrigerant. The documentation indicates that compatible indoor units include a leak sensor that can trigger a visual and audible alert, either directly or through an accessory, depending on the unit.

This safety function complements good installation practices but does not replace:

1. proper preparation of the flares;
2. tightening to the specified torque;
3. leak testing;
4. vacuum evacuation;
5. checking the lengths;
6. adjusting the charge when necessary;
7. commissioning of the three circuits.

With three zones, there are more connections than in a single-zone system. Test procedures therefore become particularly important.

A triple-zone installation that remains accessible, stable, and well protected

Mistakes to avoid with a multi-zone heat pump

Choosing the outdoor unit based solely on the sum of the indoor unit labels

The selection must account for approved combinations, actual loads, and simultaneous demand.

Placing the three indoor units without analyzing airflow

A poorly oriented unit may blow directly onto a bed, be blocked by a cabinet, or primarily condition a hallway.

Installing the outdoor unit too close to the ground

In Laval, a low mounting height increases the risk of snow obstruction and ice buildup beneath the unit.

Neglecting defrost cycles

The water produced must be able to drain away without damaging the foundation, creating a hazardous surface, or forming a block of ice against the heat pump.

Confusing independent control with completely independent operation

Each zone has its own temperature and ventilation, but all three units share the same general mode and the capacity of the same compressor.

Forgetting service access

The panels, valves, disconnect switch, and coil must remain accessible. A hedge, shed, or storage should not be added in front of the unit after installation.

Recommended maintenance around the outdoor unit

The visible area around the pad contains leaves and vegetation. This setting requires simple but regular seasonal maintenance.

We particularly recommend:

• remove leaves that accumulate behind and beneath the unit;
• keep vegetation away from the coil;
• clear snow from around the appliance;
• never blow snow from a snowblower against the grille;
• monitor ice formation beneath the structure;
• avoid placing objects on top of the unit;
• have the system inspected in the event of noise, vibration, or reduced performance.

The outdoor coil must not be cleaned with a pressure washer. Excessive pressure can bend the fins and reduce airflow.

Eligibility for financial assistance programs

HITACHI documentation indicates that the airHome Multi range is eligible for most provincial heat pump incentives. This statement does not automatically confirm the eligibility of every triple-zone combination for a specific rebate.

Eligibility may depend on:

• the AHRI number or energy reference;
• the exact combination of units;
• low-temperature capacity;
• the type of building;
• the existing heating source;
• the purchase and installation date;
• the documents provided;
• the criteria in effect at the time of the request.

We therefore verify the conditions applicable to the project rather than promising an amount based solely on the name of the product range.

The warranties presented for the HITACHI range

The brochure presents a standard seven-year warranty on the compressor and five years on parts.

A ten-year extended warranty on the compressor and parts is indicated for eligible residential installations, with online registration required. Enhanced protection may also provide up to twelve years on the compressor, ten years on parts, and ten years on labour, subject to purchasing the upgrade and complying with the conditions.

After installation, it is important to keep:

• the detailed invoice;
• model and serial numbers;
• the commissioning date;
• proof of registration;
• warranty documents;
• information about the indoor and outdoor units.

Why this Saint-Vincent-de-Paul installation stands out

The quality of a triple-zone HVAC installation can be seen in the details that will remain in place for many years.

In this project, we observe:

• a concrete slab independent of the ground;
• a securely anchored aluminum support;
• a height suited to winter conditions;
• anti-vibration pads beneath the unit;
• protected lines in line-hide covers;
• an accessible electrical disconnect switch;
• a layout that leaves the front of the fan completely unobstructed;
• enough space for inspection and maintenance.

The result is functional without making the exterior wall look cluttered. The three indoor zones benefit from a single outdoor unit, which limits clutter, the number of electrical circuits, and the visual impact around the building.

At AirGreen, we apply the same approach to our multi-zone heat pump installations in Laval, Montreal, Longueuil, on the North Shore and the South Shore. Before startup, we analyze the sizing of each room, piping routes, low-temperature capacity, drainage, support structure, and service access.

This HITACHI airHome Multi triple-zone heat pump in Saint-Vincent-de-Paul illustrates what a well-planned installation should accomplish: distributing comfort where it is truly needed, protecting the equipment from local conditions, and maintaining a clean exterior finish despite the presence of three separate circuits.