A dual-zone installation designed to maximize comfort in a very restricted outdoor space
In Candiac, on Montreal’s South Shore, our AirGreen team completed the installation of a Hitachi airHome Multi multi-zone heat pump designed to serve two distinct zones of the residence. This project perfectly illustrates a common reality in densely developed residential areas: the space available for the outdoor unit is limited, electrical equipment already occupies part of the wall, and the proximity of a deck requires particularly precise planning.
In the installation photo, the Hitachi outdoor unit is located in a narrow passage between the home’s brick wall and a privacy fence. The electricity meter, electrical service panel, foundation, basement window, and wooden deck considerably limited the positioning options.
In this context, installing a heat pump involved more than simply placing the unit on the ground. We had to create a stable, accessible, and neat configuration while organizing the refrigerant lines and connections in a way that preserved the passageway.
Why a dual-zone heat pump was the right choice for this Candiac residence
A dual-zone multi-zone heat pump connects two indoor units to a single outdoor unit. Each indoor unit can therefore serve a different room or area of the house.
This configuration is particularly appealing when a homeowner wants, for example, to:
- cool and heat a main living space;
- improve the comfort of a bedroom or floor;
- correct a significant temperature difference between two areas;
- avoid installing two separate outdoor units;
- preserve more space around the house.
The Hitachi airHome Multi system can accommodate different categories of indoor units, depending on the building’s configuration: airHome 400 or airHome 650 wall-mounted units, floor consoles, ducted units, or mini-cassettes. A single outdoor unit in the range can power up to five indoor units, depending on the selected model. For this installation in Candiac, the chosen configuration was a dual-zone solution, suitable for controlling two spaces.
Each zone has its own temperature and fan settings. One indoor unit can be running while the other remains off. However, both units must operate in a mode compatible with that of the outdoor unit: in summer, the zones can operate in cooling, dehumidification, or fan mode; in winter, they can be used for heating or fan mode.
This distinction is important. A multizone system generally cannot heat one room while simultaneously cooling another. We always explain this feature before installation so the customer clearly understands how their new system will operate day to day.
An outdoor unit installed on an elevated metal support
One of the most visible elements of this installation is the elevated metal support placed beneath the Hitachi outdoor unit.
The unit was not installed directly on the deck or simply placed on the gravel. We used a rigid support resting on an existing base, with support points designed to keep the unit level.
This method offers several advantages in Quebec’s climate.
Keeping the unit above accumulations
A heat pump used for heating must be able to draw in and discharge air freely, including during winter. An elevated installation helps keep the unit’s base away from:
- accumulated snow;
- ice;
- leaves and debris;
- rainwater;
- of persistent moisture near the ground.
Defrosting a heat pump also produces water. By installing the equipment above a draining surface and maintaining open space beneath the unit, we facilitate the drainage of this water.
Avoiding the transfer of vibrations to the deck
The wooden deck is immediately beside the outdoor unit. An installation directly attached to the deck structure could have transmitted more vibrations to the floor and adjacent rooms.
The independent support limits this risk. Antivibration mounts are also visible beneath the unit’s feet. Their purpose is to help reduce mechanical transmission between the heat pump and its supporting structure.
Preserving access to the connections
The technical side of the unit remains accessible from the passage. This accessibility is essential for future operations:
- checking the refrigerant connections;
- electrical diagnostics;
- outdoor unit maintenance;
- pressure and temperature measurement;
- heat exchanger cleaning;
- warranty service, if necessary.
An installation can be visually discreet without becoming impossible to service. In such a tight location, every inch had to be used intelligently.
Careful integration near the electrical entrance
The meter and exterior electrical panel are located directly above and to the left of the unit. This configuration required careful organization of the cables and lines.
We positioned the heat pump so that it would not block access to the electrical equipment. Technicians and authorized personnel must be able to reach the meter, conduits, and enclosures without having to dismantle the heat pump.
The refrigerant lines were routed along the foundation, then neatly grouped and secured. A cover section protects the lines where they pass near the wall and helps create a more uniform finish.
In a professional HVAC installation, appearance is not a secondary consideration. Poorly supported piping can vibrate, rub against the masonry, or be subjected to mechanical stress. Properly aligned and securely fastened lines help ensure greater installation durability.
The particular challenge of the deck and side passage
The available space between the unit and the fence is limited. The deck occupies a significant portion of the area, while a basement window lies beneath the path of the lines.
In particular, we had to avoid:
- obstructing the window;
- creating a dangerous obstacle near the deck;
- installing the unit too close to the wooden floor;
- pinching the refrigerant lines;
- making the service valves inaccessible;
- unnecessarily directing discharge air toward an immediate obstacle.
The outdoor unit’s front fan remains unobstructed. This arrangement allows air to leave the heat exchanger without being immediately blocked by the house wall.
The fence on the right is closer to the side of the unit than to its front. The unit was therefore oriented to make the best use of the available space. In this type of area, the unit’s orientation is just as important as its location.
The features of the Hitachi airHome Multi that guided our work
A multi-zone range operating with R32 refrigerant
The Hitachi airHome Multi RAM-G-N-HAA range uses R32 refrigerant. It includes outdoor units offering two to five indoor connections, with nominal cooling capacities ranging from 18,000 to 42,000 BTU/h.
In the manufacturer’s documentation, the outdoor configuration with two connections is represented by model RAM-G18N2HAA, with a nominal cooling capacity of 18,000 BTU/h and a nominal heating capacity of 22,000 BTU/h. Since the nameplate of the photographed unit is not sufficiently legible, we cannot publicly confirm the precise reference of this installation based solely on the image.
Depending on the combination of indoor units used, the range can achieve a TRÉS2 of 23.0 and a CPSC2 Region 5 of 7.85. The manufacturer also indicates heating operation down to -20 °C. These values vary according to the outdoor model, the type of indoor units, and the certified combination selected.
For an actual installation, we therefore do not rely solely on the machine’s commercial name. We verify the complete combination:
- outdoor unit model;
- model and capacity of each indoor unit;
- total connected capacity;
- line length;
- elevation difference;
- electrical requirements;
- applicable performance reference.
Piping lengths suited to multi-zone projects
For the dual-zone model presented in the Hitachi documentation, the maximum total piping length can reach 165 feet, with a maximum length of 82 feet between the units and a maximum total height difference of 66 feet.
This does not mean that using the maximum lengths is preferable for every project. A shorter, more direct route generally remains advantageous when feasible.
In Candiac, routing the lines outside made it possible to group them near the foundation rather than unnecessarily running them across the terrace or along a large part of the façade. This choice helps to:
- reduce the visual impact;
- make fastening easier;
- limit exposed sections;
- simplify future service work;
- maintain a consistent route to the two indoor zones.
Features designed for air quality and maintenance
Depending on the indoor units selected, the airHome Multi range can incorporate several useful features.
FrostWash technology uses a freeze-and-thaw cycle to clean the indoor heat exchanger coil. The Mold Guard system helps dry the internal components after cooling or dehumidification operations to limit residual moisture that can promote odors.
Some wall-mounted units are available with a PM2.5 activated carbon filter, while the mini-cassettes can be equipped with a ViroSense S filter. Compatible equipment can also be connected to the airCloud Go app using an optional interface.
These features do not replace periodic maintenance. Filters must always be cleaned, and the heat exchangers must be inspected. A self-cleaning function helps maintain performance, but it does not remove all the dust accumulated in a unit used over several seasons.
Mistakes to avoid during a multi-zone installation
A multi-zone heat pump must be sized according to the actual needs of the rooms, not by simply adding up their approximate areas.
Common mistakes include:
Choosing indoor units that are too large
An oversized unit may quickly reach the desired temperature without running long enough to provide proper dehumidification or uniform air distribution.
Underestimating the simultaneous behavior of the zones
The outdoor unit’s capacity is shared among the indoor units in operation. Therefore, simultaneous demand during very hot or very cold days must be anticipated.
Neglecting the outdoor unit’s location
An unit placed directly beneath an area where snow accumulates, too close to an obstruction, or in a space that cannot be serviced may become problematic even if the machine itself performs well.
Improvising the piping route
Refrigerant lines must not be crushed, bent beyond their proper radius, or left unsupported. Drainage for the indoor units must also be planned before drilling.
Promising a rebate without verifying the combination
The Hitachi brochure indicates that the equipment is eligible for most provincial heat pump incentives. Actual eligibility, however, depends on the program in effect, the exact combination installed, the applicable certification, and the conditions specific to the building.
At AirGreen, we verify the available technical information before presenting financial assistance as applicable. The mere fact that a brand or product range appears in a brochure does not automatically guarantee that a particular configuration will be accepted.
The final result of this installation in Candiac
The result is a compact, structured installation that makes efficient use of a complex outdoor space.
The Hitachi airHome Multi unit is:
- installed above ground;
- supported by an independent structure;
- positioned near the house without blocking the window;
- accessible from the side passage;
- connected with lines secured along the foundation;
- oriented to maintain functional clearance in front of the fan;
- integrated without unnecessarily taking up the terrace.
This project demonstrates why the installation of a multi-zone heat pump in Candiac must be planned on site. Two residences of similar size may require completely different solutions depending on the location of the electrical panel, foundation height, windows, fences, balconies, and the available route to the indoor rooms.
The AirGreen approach to multi-zone installations on the South Shore
Before recommending a dual-zone heat pump, we assess the characteristics of each space to be treated. In particular, we analyze sun exposure, room dimensions, insulation, openings, airflow, and occupancy patterns.
We then determine:
- the appropriate capacity for each indoor unit;
- the required outdoor unit capacity;
- the best location for the two indoor units;
- the refrigerant line route;
- the condensate drainage method;
- the electrical requirements;
- the type of outdoor support;
- the clearances required for airflow and maintenance.
This approach allows us to carry out HVAC installations adapted to homes in Candiac, Longueuil, Brossard, Saint-Hubert, La Prairie and other municipalities on the South Shore, as well as in Montreal, Laval and on the North Shore.
A well-chosen multi-zone heat pump can provide precise control and reduce the number of visible outdoor units. However, its performance depends just as much on the quality of the design and installation as on the specifications listed on the technical sheet.
In this project, the space constraint was not treated as an obstacle to work around quickly. It became the central focus of our planning. The elevated support, unit orientation, access to the electrical components, and orderly routing of the lines were all determined to create a reliable, accessible installation consistent with the existing layout.