A dual-zone system installed precisely between the electrical service, a basement window, and a narrow side passage
This multi-zone heat pump installation in Sainte-Julie presented a very concrete constraint: integrating a high-capacity outdoor unit into a space already occupied by the electrical meter, service entrance equipment, a vertical downspout, a basement window, and a privacy fence.
For this residential project on the South Shore of Montreal, we installed a Hitachi airHome Multi heat pump in a dual-zone configuration. A single outdoor unit thus powers two indoor units, each intended to control the comfort of a specific area of the house.
The photograph taken during the work captures a revealing moment in our installation method. The service panels are temporarily open, the refrigerant connections are accessible, and several tools are still placed near the support. This is not simply a matter of placing the equipment against a wall: before commissioning, we must connect, inspect, measure, test, and confirm that each circuit properly serves its intended zone.
The desired outcome was clear: create two independent comfort zones, preserve access to the existing electrical equipment, and build a durable installation despite a particularly tight outdoor location.
Why a dual-zone heat pump was suitable for this Sainte-Julie home
A dual-zone multi-zone heat pump uses a single outdoor unit to power two indoor units. This configuration is often chosen when a residence has two areas with different needs, for example:
- an open-plan ground floor and an upper floor;
- a living room and a primary bedroom;
- a family area and an office;
- an addition that is more difficult to heat or cool;
- two levels with different sun exposures.
Rather than installing two compressors around the house, the Hitachi system combines heating and cooling production in a single outdoor unit. This solution reduces the equipment footprint, which was particularly advantageous here because the side passage offered very little free space.
Each indoor unit has its own setpoint and fan speed. One zone can operate while the other remains off. Occupants can therefore adjust the temperature according to the actual use of the rooms rather than treating the entire residence uniformly.
However, it is important to understand a key feature of multi-zone systems: the indoor units must operate in compatible modes. In summer, they can be used for cooling, dehumidification, or ventilation. In winter, they operate in heating or ventilation mode. One zone therefore cannot normally heat while another is cooling at the same time.
We always explain this logic before installation. It helps prevent misunderstandings about how the system works and helps the homeowner use their new system effectively.
A complex location beneath the electrical equipment
The Hitachi outdoor unit was positioned immediately below the area where the residence’s meter and electrical components are located.
This proximity required careful planning. In particular, it was necessary to:
- maintain reasonable access to the meter;
- avoid blocking the electrical cabinets and conduits;
- leave the space needed for future electrical work;
- prevent any contact between the refrigerant lines and the electrical components;
- maintain sufficient clearance around the heat pump;
- take into account the basement window located just to the left.
We therefore installed the unit slightly offset from the meter’s axis. This positioning keeps the electrical equipment visible and accessible while making efficient use of the available portion of the walkway.
The front of the heat pump remains unobstructed, which facilitates the discharge of air produced by the fan. The technical side is also accessible for commissioning and future service work.
In an HVAC installation, accessibility is not limited to the day of the work. A technician must be able to reach the service valves, electrical terminals, sensors, and equipment panels several years after installation.
A raised unit rather than one placed directly on the ground
The heat pump rests on an independent metal support positioned above a stable base. This method prevents the equipment from being placed directly on gravel or on a surface exposed to moisture.
The support serves several essential functions.
Protecting the bottom of the unit from snow and ice
In Sainte-Julie, as elsewhere on the South Shore, a heat pump may be surrounded by snow for several months. A unit that is too low may have its openings partially obstructed. Ice produced during defrost cycles can also accumulate beneath the unit.
Elevation facilitates:
- draining defrost water;
- maintaining clear space beneath the machine;
- seasonal cleaning;
- reducing contact with ground moisture;
- air circulation around the base.
Limiting vibration transmission
Supports are placed between the heat pump and the mounting base. They help reduce the mechanical transmission of vibrations to the metal structure.
This detail is particularly relevant when the equipment is installed near a bedroom, living room, or foundation. A modern heat pump can be quiet, but improper mounting can amplify vibrations and create noise that does not come directly from the compressor.
Keeping the installation level
Stability and leveling are essential for the unit to function properly. A rigid structure makes it possible to precisely control the machine's footing despite the presence of gravel and changes in the terrain.
A line route adapted to the basement window
The window at the bottom of the wall limited the routing options. We had to avoid placing the lines in front of the opening or obstructing its use.
The lines were therefore routed horizontally above the window, along the foundation, and then directed toward the outdoor unit. They are supported at regular intervals to reduce movement, sagging, and friction against the wall.
This arrangement protects the lines while maintaining visual access to their route. It also makes it easier to identify a problem during future HVAC maintenance.
The refrigerant lines of a dual-zone system should not be treated as mere accessory pipes. They carry refrigerant between the outdoor unit and each indoor unit. Their diameter, length, bends, and the quality of their connections directly affect the system's reliability.
A professional installation requires, among other things:
- clean cutting of the copper tubing;
- precise preparation of the flares;
- tightening according to the manufacturer's requirements;
- a leak test;
- proper drainage of the circuits;
- checking the total length;
- continuous insulation of the lines;
- protecting exposed sections.
What temporarily opening the service panels shows
In the photograph, several brass fittings are visible on the side of the unit. The panels had not yet been closed at the time the photo was taken, because our team was in the connection and inspection phase.
This step provides access to the different circuits of the multi-zone heat pump. In a dual-zone configuration, each indoor unit has its own refrigerant connection to the outdoor unit.
Before finalizing the panels, we must ensure that:
- each pair of lines corresponds to the correct zone;
- the connections are properly tightened;
- the circuits are leak-tight;
- the electrical connections comply;
- communications between the units are working;
- no cables can be pinched when closing;
- the protective covers and caps are put back in place.
This check is essential. A communication mix-up or incorrect pairing between circuits can cause operating issues that are difficult to diagnose once the installation has been completely closed up.
Technical specifications of the Hitachi airHome Multi range
The Hitachi airHome Multi RAM-G-N-HAA range includes multi-zone systems with Inverter technology using R32 refrigerant. Depending on the outdoor model, it can power two to five indoor units and offer a rated cooling capacity ranging from 18,000 to 42,000 BTU/h.
For the two-connection outdoor configuration shown in the Hitachi brochure, the RAM-G18N2HAA model notably features:
- a rated cooling capacity of 18,000 BTU/h;
- a rated heating capacity of 22,000 BTU/h;
- a heating range down to -20 °C;
- a TRÉS2 that can reach 23,0 with a ductless combination;
- a CPSC2 Region 5 that can reach 7,85;
- a maximum total piping length of 165 feet;
- two refrigerant connections;
- an advertised outdoor sound level of 52 dB(A) at high speed.
These data describe the dual-zone model in the range, but the exact reference of the installed unit must always be confirmed on its rating plate and in the project-specific technical combination. The complete range also includes models with three, four, and five connections.
A range compatible with several types of indoor units
One of the advantages of airHome Multi is its flexibility. Depending on the building’s needs, the outdoor unit can be paired with several indoor unit formats:
- airHome 400 wall-mounted;
- airHome 650 wall-mounted;
- airHome Floor console;
- airHome Mini Cassette;
- airHome Ducted unit.
This variety makes it possible to adapt each zone to the home’s architecture. A wall-mounted unit is well suited to an open-concept area, while a floor console may be better suited to a low wall or an attic space. A ducted unit can serve a zone discreetly when access to the ceiling or attic allows it.
In a dual-zone installation, the two indoor units do not need to have the same capacity. Their selection should match the actual loads of each room.
How we determine the capacity of each zone
BTU selection is not based solely on floor area. We must also consider:
- ceiling height;
- the number and size of windows;
- the orientation of the house;
- insulation quality;
- doors between rooms;
- natural air circulation;
- the floor where the zone is located;
- heat produced by appliances and occupants;
- daily use of the area.
A room with many west-facing windows may require more cooling than a room of the same size on the north side. Conversely, an oversized indoor unit may reach the requested temperature too quickly, operate in short cycles, and remove humidity less effectively in summer.
Selecting a multi-zone system also requires an analysis of shared capacity. When both units operate simultaneously, the outdoor unit distributes its capacity between the zones. We must therefore choose a combination that matches the residence’s simultaneous needs.
Heating down to -20 °C: what this really means
Hitachi indicates continuous heating operation down to -20 °C for the airHome Multi line. This feature is particularly interesting for a residence in Sainte-Julie, where the heat pump will be required to operate during a large part of the winter.
However, available capacity decreases as the outdoor temperature drops. In the product line’s technical table, the dual-zone model has a maximum heating capacity of approximately 14,300 BTU/h at -15 °C and 9,700 BTU/h at -20 °C.
This information is more useful than the minimum operating temperature alone. A heat pump can continue operating at very low temperatures without necessarily covering the building’s entire heating load.
Depending on the insulation, floor area, and configuration of the home, supplemental heating may still be necessary during the coldest periods. We assess this reality before presenting a heat pump as a primary or supplementary heating source.
Air quality, internal cleaning, and smart control
Depending on the type of indoor unit selected, the Hitachi airHome Multi range may offer several features related to air quality and ease of use.
FrostWash
The FrostWash technology uses a freezing and thawing process to clean the indoor coil. It helps remove contaminants that can accumulate on the heat exchanger over time.
Mold Guard
The Mold Guard function circulates air to dry the internal components after a cooling or dehumidification cycle. This operation may last approximately 60 minutes and is intended to reduce conditions conducive to the formation of odors and mold.
Filtration suited to the selected units
Wall-mounted units may include a PM2.5 activated carbon filter, while slim cassette units can be equipped with a ViroSense S filter. Exact specifications depend on the selected indoor model.
airCloud Go
An optional interface may allow system control with the airCloud Go app. It then becomes possible to schedule operation, adjust settings, and view certain data remotely.
These features do not eliminate the need to clean the filters. Even a unit equipped with a self-cleaning cycle requires regular maintenance to maintain good airflow.
Errors this installation helps prevent
Installing the unit too close to the ground
A heat pump used in winter must be raised high enough to reduce the risk of obstruction from snow and ice buildup beneath the unit.
Blocking a window or service access
The best location is not simply the space where the unit can fit. Windows, electrical panels, and areas needed for maintenance must remain accessible.
Neglecting fan clearance
The outdoor fan must be able to discharge air without immediately encountering an obstruction. Poor airflow can reduce performance and increase operating strain.
Leaving the pipes unsupported
Improperly secured pipes can vibrate, sag, or rub against the masonry. In this installation, the horizontal run was supported along the foundation.
Close the panels before the final checks
Commissioning must be completed before the technical access points are closed. We check every circuit, every connection, and every zone before completing the finishing work.
Automatically assuming eligibility for financial assistance
The brochure indicates that the range may be eligible for most provincial heat pump incentives. However, actual eligibility depends on the exact combination, the applicable certification, and the program rules in effect when the application is submitted.
We therefore verify the model number, capacity, and certified reference rather than relying solely on the Hitachi airHome Multi trade name.
The result: two comfort zones and an organized outdoor installation despite limited space
This Sainte-Julie installation demonstrates that a challenging location can accommodate a multi-zone heat pump when every detail is planned before drilling and connection.
The outdoor unit is now:
- installed on a raised metal support;
- kept away from gravel and accumulations;
- positioned without obstructing the basement window;
- accessible for maintenance;
- integrated near the electrical service without blocking access to it;
- connected to two distinct indoor zones;
- oriented to preserve the clearance in front of the fan.
The homeowner therefore benefits from more precise temperature control in two areas of the house, without multiplying the number of outdoor units in the yard.
Our approach to multi-zone heat pumps in Sainte-Julie and Greater Montreal
At AirGreen, we install heat pumps, wall-mounted air conditioners, and multi-zone systems in Sainte-Julie, Longueuil, Boucherville, Saint-Bruno-de-Montarville, Candiac, throughout the South Shore, as well as in Montreal, Laval, and on the North Shore.
For every project, we check:
- the heating and cooling needs of each zone;
- the combination of indoor units;
- the location of the outdoor unit;
- the available clearances;
- the route of the refrigerant lines;
- condensate drainage;
- the capacity of the electrical circuit;
- the access required for maintenance;
- the stability of the support;
- the eligibility conditions for the applicable programs.
This Hitachi airHome Multi installation in Sainte-Julie is a good example of our approach: using a limited space without compromising access, stability, or connection quality. The unit takes up a measured amount of space, but every element around it was considered, from the electrical meter to the basement window.