A compact installation between the exterior siding, masonry, and circulation space
This Hitachi airHome Multi multizone heat pump installation in Longueuil illustrates a common type of project on the South Shore: integrating a high-capacity outdoor unit into a limited space while maintaining safe access around the building and protecting the equipment from winter conditions.
The owner wanted to heat and cool two distinct areas of the residence without installing two outdoor units. We therefore chose a dual-zone configuration, which supplies two indoor units from a single outdoor heat pump.
In the photo, the unit is located in a covered, relatively narrow passage between a wall covered with horizontal siding and a section of masonry. A wooden platform is in the foreground, while outdoor furniture and a decorative panel are nearby. The available space therefore had to be used precisely.
Our AirGreen team installed the unit on a raised metal floor stand, securely fastened to the concrete surface. This solution protects the heat pump, facilitates maintenance, and keeps it from sitting directly on the ground, where moisture, ice, and debris could affect its operation over the seasons.
Why a dual-zone heat pump was the right fit for this Longueuil property
A multizone system is particularly well suited to properties where two spaces have different comfort needs. Examples include:
- a ground floor and an upper floor;
- an open-concept area and a bedroom;
- a main living area and an office;
- two remote sections that do not benefit from the same airflow;
- a difficult-to-serve addition to the existing system.
Each indoor unit can be adjusted independently with its own setpoint, fan speed, and operating settings. One zone can also be turned off while the other continues heating or cooling.
The Hitachi airHome Multi series can power two to five indoor units, depending on the outdoor model. For a two-connection configuration, the manufacturer's documentation presents the RAM-G18N2HAA model, with a nominal capacity of 18,000 BTU/h in cooling and 22,000 BTU/h in heating.
This principle reduces the outdoor footprint compared with two individual heat pumps. In Longueuil, where houses, duplexes, and residential buildings sometimes have narrow yards or limited side passages, this advantage is considerable.
A location chosen to protect the unit without enclosing it
The choice of outdoor location directly affects the performance, noise level, service life, and ease of maintenance of a heat pump.
In this project, the unit is positioned near the wall, but it remains accessible from the front and right side. Its large front fan can discharge air without being blocked by a solid fence or permanent structure.
The passage appears to be partially protected by the structure, which may reduce direct exposure to precipitation. However, this protection must never create an overly enclosed space. A heat pump must be able to draw in and discharge a large volume of air. When the expelled hot or cold air immediately returns toward the coil, the unit may recirculate its own air, reducing its efficiency.
We therefore check several factors before permanently securing the unit:
- the clearance in front of the fan;
- the distance between the coil and the wall;
- the presence of fences, steps, or furniture;
- access to the service panels;
- the routing of the refrigerant lines;
- drainage in heating mode;
- the movement of occupants around the installation.
This preparation is just as important as the choice of model.
A metal support anchored to the concrete
One of the most visible details of this installation is the elevated aluminum or galvanized steel support installed beneath the Hitachi unit.
The four feet rest on support plates secured to the concrete slab. The heat pump is then attached to the upper crossbar with bolts and anti-vibration pads.
Why not simply place the unit on the ground?
Installing directly on a low slab may seem simpler, but it has several disadvantages in the climate of Longueuil:
- snow accumulation around the base;
- ice formation during defrost cycles;
- prolonged contact with water;
- faster clogging by leaves and debris;
- difficulty cleaning underneath the unit;
- increased risk of long-term corrosion.
The elevated support keeps the equipment at a more practical height and leaves open space beneath the chassis. This makes it easier to inspect the base, remove debris, and manage the water produced during defrosting.
The role of anti-vibration pads
The visible pads beneath the mounting points help reduce mechanical transmission between the unit and its support. Without this protection, certain compressor frequencies could be transmitted to the metal structure and then to the slab or building.
Inverter technology varies the compressor speed. Because the speed changes according to demand, vibrations can also vary. Stable mounting, combined with appropriate supports, helps maintain quiet operation.
A high-efficiency system for two residential zones
The Hitachi airHome Multi series uses inverter technology to adjust its output according to actual demand. Rather than constantly switching between completely off and full power, the compressor can slow down as indoor temperatures approach the setpoints.
For the ductless dual-zone configuration specified in the documentation, the performance figures include:
- 18,000 BTU/h of rated cooling capacity;
- cooling modulation from 7,000 to 20,500 BTU/h;
- 22,000 BTU/h of rated heating capacity;
- heating modulation from 9,000 to 24,000 BTU/h;
- a TRÉ2 of 12.5;
- a TRÉS2 of up to 23.0;
- a Region 5 CPSC2 of up to 7.85;
- a COP of 3.3 at 8 °C, depending on the ductless configuration.
These figures show why precisely matching the indoor units is important. A multi-zone system should not be selected simply by adding the capacities listed on the wall-mounted units. The certified combination, the building load, and the capacity actually available when both zones simultaneously call for heating or cooling must be verified.
Heating down to -20 °C: what it really means
The manufacturer specifies a heating operating range down to -20 °C for the outdoor units in this series. For the dual-zone configuration, the stated maximum heating capacity is approximately 14,300 BTU/h at -15 °C and 9,700 BTU/h at -20 °C.
These figures are particularly useful for explaining a frequently misunderstood concept: a heat pump can continue operating in very cold weather, but its available capacity decreases as the outdoor temperature drops.
That is why we always assess:
- the home’s heat loss;
- the existing supplemental heating system;
- the temperature desired by the occupants;
- the building’s insulation and airtightness;
- the distribution of heat between rooms.
For many properties in Longueuil, a multi-zone heat pump can cover a significant portion of annual heating and cooling needs. Supplemental heating nevertheless remains relevant during the coldest periods or in rooms not directly served.
Two independent temperatures, but one shared main mode
The term “dual zone” may suggest that the two indoor units operate like two completely separate systems. They are independent in terms of temperature and ventilation, but they share the same refrigerant circuit.
In practice:
- one unit can operate while the other is stopped;
- each room can have a different temperature setpoint;
- each unit can use a different fan speed;
- the two units must nevertheless remain in compatible modes.
In summer, the outdoor system is in cooling mode. The indoor units can then operate in cooling, dehumidification, or fan mode, depending on the available options. In winter, they use heating or fan mode. One zone cannot request heating while the other simultaneously requests cooling.
We always explain this feature during commissioning. It helps the owner understand why one unit may temporarily wait when the two remote controls request opposite modes.
A range of indoor units suited to different rooms
The airHome Multi outdoor unit can be paired with different styles of indoor units. Hitachi documentation notably presents:
- the airHome 400 wall-mounted units;
- the airHome 650 wall-mounted units;
- the airHome Floor floor consoles;
- the mini-cassette units;
- the concealed ducted units.
The available capacities generally range from 7,000 to 24,000 BTU/h, depending on the format.
This variety allows us to adapt the system to the interior layout. A wall-mounted unit is often suitable for a large open room, while a floor console may be better suited when there is insufficient clearance above the windows. A ducted unit can serve several small rooms when the ceilings and mechanical spaces allow it.
The choice must remain consistent with the capacity of the outdoor unit. Installing oversized indoor units does not guarantee better comfort. Instead, it may cause less stable cycles, insufficient dehumidification in summer, or uncomfortable air distribution.
Maintenance and air-quality technologies
Depending on the indoor units selected, Hitachi offers several functions related to coil cleanliness and filtration.
FrostWash
The FrostWash technology creates a freeze-and-thaw cycle on the indoor heat exchanger to help loosen and remove accumulated contaminants. The goal is to maintain cleaner heat exchange and consistent airflow.
Mold Guard
The Mold Guard function circulates air to dry the internal components after a period of cooling or dehumidification. The manufacturer indicates a cycle of approximately 60 minutes intended to limit conditions conducive to odors and mold.
Filtration by unit type
Some units include a PM2.5 activated carbon filter, while the mini-cassettes use the ViroSense S filter. These filters can improve the management of certain particles and odors, but they do not replace regular maintenance.
The owner must clean the pre-filters at the recommended frequency and monitor the following signs:
- reduced airflow;
- unusual noise;
- persistent odor;
- visible buildup on the fan;
- water that drains poorly;
- increased time required to reach the temperature.
Regular HVAC maintenance protects performance and makes it possible to check the condition of the drains, coils, and electrical connections.
R32 refrigerant and installation safety
The airHome Multi heat pump uses R32Compatible indoor units are designed with a leak sensor that can activate an indicator light and an audible alarm, depending on the model and accessories.
The presence of this technology does not diminish the importance of precise refrigeration work. We perform a complete procedure that includes, among other things:
- preparing and flaring the lines;
- tightening according to applicable requirements;
- leak testing;
- evacuating the system;
- checking vacuum stability;
- opening the valves;
- testing in the various modes;
- checking each indoor drain.
A slow leak can reduce efficiency before causing the system to shut down. Connections must therefore be accessible and protected from mechanical stress.
Electrical data for the dual-zone configuration
For the RAM-G18N2HAA model, the documentation indicates:
- rated voltage of 208-230 V;
- single-phase power at 60 Hz;
- minimum circuit ampacity of 16 A;
- maximum overcurrent protection of 25 A;
- maximum advertised outdoor sound level of 52 dB(A).
In the photo, an outdoor electrical box is visible on the wall to the right, near the unit. This proximity facilitates local power shutoff during maintenance.
The breaker and wiring selection must always follow the nameplate of the actual unit installed and the applicable electrical requirements. General brochure values do not replace on-site verification.
A Visible ÉnerGuide Label on the Unit
The photographed unit bears an ÉnerGuide label, as well as AirGreen identification. This label provides access to efficiency information related to the certified combination.
For a multi-zone system, it is important to retain:
- itemized invoice;
- model numbers of the indoor and outdoor units;
- serial numbers;
- the AHRI reference, when applicable;
- commissioning documents;
- warranty registration documents.
This information may be required for a warranty, a grant application, or future technical service.
Grants: Why the Combination Number Matters
The brochure indicates that the series may qualify for several provincial heat pump incentives. This statement does not mean that all combinations and all properties will automatically receive financial assistance.
Eligibility may depend on:
- exact certified combination;
- low-temperature performance;
- rated capacity;
- program in effect on the installation date;
- building type;
- residential or rental use;
- documents provided by the contractor.
At AirGreen, we avoid confirming an amount based solely on the series name. We verify the model numbers and the applicable program requirements before presenting an estimate of financial assistance.
What This Longueuil Installation Reveals About the Quality of an HVAC Project
At first glance, the photo simply shows an outdoor heat pump on a support. In reality, several technical decisions come together in this compact space:
- selecting a system capable of serving two zones;
- choosing a protected but sufficiently ventilated location;
- stable support anchored to the slab;
- clearance beneath the unit;
- cushion mounts to limit vibrations;
- access to the electrical disconnect;
- maintaining a functional passage around the residence;
- a position that allows for future maintenance.
These details distinguish a durable HVAC installation from one carried out merely to get the machine running on the day of the work.
Mistakes to avoid in a narrow outdoor passage
Blocking the fan with objects
The front of the unit must remain clear. Avoid placing boxes, storage bins, furniture, or seasonal materials there.
Allowing debris to accumulate under the support
The space beneath the heat pump makes cleaning easier, but it must be used. Leaves, dust, and webs can retain moisture and obstruct drainage.
Blocking airflow with a decorative panel
A screen can improve the appearance of the installation, but it must not restrict air intake or discharge. Any enclosure added after the work is completed must comply with the manufacturer’s clearance requirements.
Neglecting defrost water
In winter, water produced during defrosting can freeze under or in front of the unit. Drainage must be monitored to prevent an accumulation of ice from reaching the base of the unit.
Ignoring service access
The side and electrical panels must remain accessible. Equipment surrounded by furniture or wedged against a structure costs more to maintain and may require moving heavy objects before each service call.
The AirGreen approach in Longueuil and Greater Montreal
We install multi-zone heat pumps, wall-mounted air conditioners, and central systems throughout Longueuil, Montreal, the North Shore, and the South Shore.
Our work goes beyond installing the selected equipment. We also evaluate:
- the capacity required for each zone;
- the building’s thermal characteristics;
- the route of the lines;
- drainage options;
- electrical constraints;
- noise near bedrooms and neighbors;
- future maintenance requirements;
- the exterior finish.
In this Longueuil residence, the dual-zone solution served two spaces with a single outdoor unit while maintaining a compact, accessible installation. The raised support protects the equipment, the support points limit vibrations, and the location makes efficient use of an outdoor area that would otherwise be difficult to arrange.
The result meets a simple but demanding goal: providing consistent comfort in both summer and winter without compromising airflow, maintenance, or system durability.