A high-mounted installation designed to cool and heat two distinct zones
In Delson, on Montreal’s South Shore, we installed a HITACHI airHome Multi dual-zone multi-zone heat pump in an outdoor configuration that required particularly careful planning. As shown in the project photo, the outdoor unit was installed high on a brick wall located in a relatively narrow passage between two sections of the building.
This type of project involves more than simply mounting a heat pump on the wall. Every detail matters: the strength of the support, access to the refrigerant connections, air circulation, drainage of defrost water, protection of the piping, proximity to the roof, and the ability to perform future HVAC maintenance without dismantling part of the installation.
Our objective was clear: to create a system capable of serving two independent indoor spaces while using a single outdoor unit. The HITACHI airHome Multi system meets this need precisely thanks to its Inverter technology and its ability to modulate its operation according to the actual demand of each zone.
Why a dual-zone heat pump was suitable for this Delson property
In many homes in Delson, Candiac, La Prairie, and other municipalities on the South Shore, rooms do not all have the same heating and cooling needs. An open-concept area exposed to the sun can quickly become hot, while a bedroom or office elsewhere in the home remains comfortable.
With a multi-zone heat pump, each indoor unit has its own settings:
- an independent setpoint temperature;
- a fan speed suited to the room;
- the ability to be turned on or off separately;
- an airflow rate corresponding to the zone’s size and use.
The airHome Multi system allows multiple indoor units to be connected to a single outdoor unit. The range includes configurations that can serve two to five zones, depending on the selected model. For this installation in Delson, the selected configuration was a dual-zone system, meaning two indoor units connected to the same outdoor unit.
This solution reduces the space required outdoors and avoids installing two separate condensers. It also creates a more orderly appearance around the building, which was particularly important in this restricted location.
An outdoor unit installed high on a masonry wall
The most visible feature of this HVAC installation in Delson is the position of the outdoor unit. It rests on two sturdy metal wall brackets, firmly anchored into the masonry.
This installation method offers several concrete advantages.
Protection against snow accumulation
On the South Shore, snow accumulation around a heat pump can reduce airflow and impair winter operation. By raising the unit, we limit the risk of it being partially buried after a storm or while clearing the passage.
A heat pump must be able to freely intake and discharge air. A unit installed too close to the ground can be affected by:
- snowbanks;
- ice produced during defrost cycles;
- splashes and dirt;
- leaves and debris that accumulate in the fall.
The height selected for this installation therefore helps preserve the clearances required around the outdoor coil.
Freeing up ground space
The area visible in the photo also serves as a passageway and provides access to the building. A ground-level installation would have occupied part of this already narrow space. Wall mounting keeps the ground clear while positioning the heat pump in a functional location.
This solution is common in denser residential areas of Montreal, Laval, Longueuil, Delson, and the South Shore, where side yards are sometimes too narrow to accommodate a heat pump on a conventional base.
Mechanical stability of the installation
A multi-zone unit is generally heavier than a small single-zone wall-mounted heat pump. The supports must therefore be selected and installed according to the weight of the unit, potential vibrations, and weather conditions.
We used a double-arm metal structure with diagonal bracing. The anchor points were distributed across the masonry to support the equipment securely. Anti-vibration pads were also placed between the unit and its supports to limit the transmission of vibrations to the building.
A major constraint: the proximity of the roof
The unit is located beneath a section of the roof, near the soffit. This configuration required particular attention to maintain sufficient clearance for airflow and technical access.
An installation that is too close beneath an overhang can create several problems:
- recirculation of discharged air;
- difficult access to the service panel;
- ice accumulation from the roof;
- water runoff onto the unit;
- difficulty cleaning the outdoor coil.
We positioned the unit to preserve usable space around its essential components. The front fan remains completely unobstructed, while the side containing the connections and service valves remains accessible.
The choice of location also had to take the roof slope and possible rainwater runoff into account. A heat pump should not be placed directly beneath an area where water or melting snow continuously falls onto the casing.
Protected and organized piping despite a complex route
The photo shows the path of the refrigerant lines beneath and behind the outdoor unit. In a dual-zone installation, several lines must be routed between the condenser and the indoor units.
Each zone requires, among other things:
- a liquid line;
- a refrigerant gas line;
- an appropriate communication and power cable;
- an indoor-side condensate drain.
For HITACHI airHome Multi outdoor units, the liquid connections generally use a diameter of 1/4 po, while the gas connections vary according to the capacity of each indoor unit. On the two-connection outdoor model RAM-G18N2HAA, for example, both gas outlets are 3/8 in. However, the final diameter selection must always correspond to the indoor models actually installed and the manufacturer's specifications.
We grouped the lines together and used a brown exterior covering to better integrate them with the building materials. This finish protects the insulated pipes against:
- ultraviolet rays;
- accidental impacts;
- moisture;
- birds and small animals;
- premature deterioration of the insulation.
Choosing a color that matches the exterior cladding also improves the appearance of the installation. A high-performance heat pump must be properly installed from a technical standpoint, but its visual integration remains important, especially when it is placed in a visible area.
An accessible and safe electrical installation
Near the appliance, we can see the outdoor electrical disconnect. It allows the heat pump to be quickly isolated during maintenance, inspection, or repair.
The HITACHI airHome Multi range operates on a 208 to 230-volt, single-phase, 60 Hz power supply. Circuit requirements vary according to the outdoor model. In the range presented by the manufacturer, the minimum circuit ampacity is between 16 and 30 amps, while the maximum overcurrent protection ranges from 25 to 50 amps depending on the capacity and number of connected units.
These values must never be estimated. Before each installation, we verify:
- the exact model of the outdoor unit;
- the required minimum ampacity;
- the maximum permitted protection;
- the wire gauge;
- the capacity available in the electrical panel;
- compliance of the installation with applicable requirements.
Oversized protection may not adequately protect the circuit, while a breaker that is too small may cause repeated tripping.
What the HITACHI airHome Multi system brings to everyday comfort
One outdoor unit for multiple types of indoor units
One of the key advantages of the airHome Multi system is its flexibility. Depending on the property’s layout, it can be combined with different types of indoor units:
- airHome 400 wall-mounted units;
- airHome 650 wall-mounted units;
- floor consoles;
- ceiling cassettes;
- concealed ducted units.
This option makes it possible to design a different solution for each room. A wall-mounted unit may be suitable for an open-concept area, while a ducted unit can be used in an area where the owner wants to maintain a more discreet appearance.
The range includes indoor units generally ranging from 7,000 to 24,000 BTU/h, depending on the type and model. Sizing must nevertheless be determined through a calculation suited to the building, rather than based solely on floor area.
Inverter modulation better suited to actual needs
Inverter technology allows the heat pump to modulate the compressor’s output. Rather than operating only at full capacity and then shutting off abruptly, the system can adjust its output according to demand.
This modulation helps to:
- maintain a more stable temperature;
- reduce uncomfortable fluctuations;
- limit on-off cycles;
- improve efficiency during periods of moderate demand;
- reduce noise levels when full power is not required.
In a dual-zone system, this modulation is particularly useful. When both rooms call for heating or cooling, the outdoor unit distributes its capacity between the active indoor units. When only one zone is operating, the system adjusts its output accordingly.
However, one important rule must be kept in mind: the indoor units of a multi-zone system must operate in compatible modes. In summer, they can use cooling, dehumidification, or fan mode. In winter, they can use heating or fan mode. One unit cannot heat while another is cooling at the same time using the same outdoor unit.
Performance suited to the climate of the Montreal region
Depending on the model and combination of indoor units, the airHome Multi range offers a SEER2 of up to 23.0 and a HSPF2-5 of up to 7.85. The manufacturer also indicates an operating range in heating mode down to -20 °C.
This data is important, but it must be interpreted correctly. Available heating capacity decreases as the outdoor temperature drops. For example, the manufacturer's technical tables indicate different maximum capacities at -15 °C and -20 °C depending on the outdoor model.
For a property in Delson, it is therefore essential to consider:
- the building's heat losses;
- the level of insulation;
- the floor area and layout of the rooms;
- the number and size of windows;
- exposure to sun and wind;
- the presence of supplemental heating.
A well-chosen multi-zone heat pump can cover a significant portion of annual needs, but its sizing must be based on the home's actual conditions.
Features focused on air quality and maintenance
Depending on the indoor unit selected, the system may include several useful technologies.
FrostWash technology
FrostWash technology freezes moisture on the indoor coil, then melts it to carry away some of the accumulated contaminants. This process helps keep the heat exchanger cleaner and preserve airflow.
This function does not replace periodic maintenance or professional cleaning, but it can help reduce dirt buildup on the coil.
Mold Guard function
After a cooling or dehumidification cycle, the Mold Guard function circulates air to dry the internal components for approximately 60 minutes. This step helps limit residual moisture that could promote odors or mold growth.
Filtration suited to the indoor model
Some wall-mounted units use a PM2.5 activated carbon filter, while the mini-cassettes may be equipped with the ViroSense S filter. The exact features therefore depend on the type of indoor unit selected.
Remote control with the airCloud Go interface
The system can be paired with an optional airCloud Go Wi-Fi interface. This allows users, among other things, to schedule operating periods and change settings remotely.
This feature is useful for homeowners who want to:
- lower the temperature when they are away;
- turn the heating back on before they return;
- adjust a zone without moving around;
- create separate schedules based on room usage.
Some indoor units can also receive an airPoint Room H700 wall-mounted thermostat or be connected to a compatible third-party thermostat, although some advanced functions may then be unavailable.
Mistakes we avoid during a multi-zone installation
A dual-zone heat pump can provide excellent comfort, but only if the system design is coherent.
Common mistakes include:
-
Installing an outdoor unit too close to a roof or an obstacle.
Insufficient clearance can cause air recirculation and complicate maintenance. -
Choosing indoor capacities based solely on floor area.
Two rooms of the same size may have very different needs depending on their windows and exposure. -
Ignoring the minimum or maximum line length.
The airHome Multi range has specific limitations. Depending on the outdoor model, the maximum total line length can range from 165 to 262 feet. -
Using an unsuitable pipe diameter.
The diameter of the refrigerant lines varies according to the capacity of the indoor unit. -
Placing the equipment too low in a snow-prone area.
An elevated installation, like the one completed in Delson, reduces this risk. -
Making the service valves inaccessible.
The connections must remain accessible for commissioning and future work. -
Forgetting to drain defrost water.
In winter, this water can freeze beneath the unit and create significant buildup.
An installation designed for today and the years to come
The quality of a heat pump installation in Delson is also measured by how easy it is to maintain. On this project, the unit was positioned to preserve access to the electrical panel, service valves, fan, and outdoor heat exchanger.
A high-mounted installation will naturally require suitable access equipment during maintenance. However, this compromise was justified by the passageway constraints, protection against snow, and the need to preserve ground space.
At AirGreen, we adapt the installation method to the building rather than applying the same solution everywhere. A property in Delson does not necessarily have the same constraints as a duplex in Montreal, a condominium in Laval, a home in Longueuil, or a residence on the North Shore.
In every case, we analyze the routing of the lines, wall structure, clearances, electrical supply, drainage, and accessibility before confirming the final location.
The result achieved in Delson
This HITACHI airHome Multi dual-zone installation now serves two spaces with a single outdoor unit. The wall-mounted setup keeps the passageway clear, better protects the equipment from snow accumulation, and maintains an orderly arrangement of the lines.
The result brings together several essential elements:
- a sturdy wall-mounted structure;
- an outdoor unit elevated above the ground;
- accessible connections;
- an aesthetically pleasing protection for the piping;
- an electrical disconnect switch nearby;
- a multi-zone configuration suited to two rooms;
- a cohesive integration with the building’s materials.
For homeowners comparing a single-zone ductless heat pump with a multi-zone heat pump, this project demonstrates the value of a dual-zone system when two spaces have different needs but available outdoor space remains limited.