Transforming a narrow rear balcony into a reliable technical location for a dual-zone heat pump
This multizone heat pump installation in Anjou had to solve a common problem in Montreal's residential neighborhoods: how to add an efficient heating and cooling system when there is practically no floor space available around the building?
In this Anjou residence, the selected location was on a narrow rear balcony, between a brick wall and a wooden railing. The outdoor unit had to share this space with access points to the dwelling, existing ducts, and electrical installations without making the balcony unusable.
Our AirGreen team installed a Hitachi airHome Multi heat pump in a dual-zone configuration, capable of powering two indoor units from a single outdoor unit. This solution makes it possible to condition two distinct areas of the residence while avoiding the addition of two compressors on an already limited balcony.
The installation image shows several important technical choices: an outdoor unit elevated on a freestanding metal structure, vibration-damping supports beneath the unit, positioning parallel to the railing, and an orientation designed to direct the air discharge toward the open part of the balcony.
Why a multizone heat pump was better suited to this Anjou space
A single-zone heat pump would have made it possible to heat and cool only one main room. However, the homeowner wanted to improve comfort in two different areas of the residence.
The dual-zone configuration met this objective with:
- a single outdoor unit;
- two indoor units that can be adjusted individually;
- a temperature adapted to the actual use of each room;
- fewer visible pieces of equipment on the balcony;
- a single main electrical circuit for the outdoor equipment;
- more cohesive integration with the existing architecture.
Each indoor unit can have its own temperature setting and fan speed. One zone can operate while the other remains off, avoiding unnecessary conditioning of an unoccupied room.
However, the two zones must operate in a compatible mode. When the system is cooling, the indoor units can be used for cooling, dehumidification, or ventilation. When the outdoor unit is operating in heating mode, the zones can heat or ventilate, but one unit cannot normally cool while the other heats.
This detail is always explained as part of our recommendations. A proper HVAC installation begins with selecting the right equipment, but also with a clear understanding of how it will operate day to day.
The main challenge: maintaining a usable passageway on the balcony
The outdoor unit occupies a significant portion of the available width. We had to prevent it from turning the balcony into a permanent obstacle.
The positioning was therefore determined based on several factors:
- the balcony’s width;
- the proximity of the brick wall;
- the height and structure of the guardrail;
- the route of the refrigerant lines;
- the location of the electrical device;
- the direction of the air discharged by the fan;
- the access required for maintenance;
- occupant movement.
The heat pump was aligned lengthwise along the balcony rather than placed perpendicular to the building. This configuration reduces its footprint in the passageway and preserves access along the wall.
In Montreal buildings, particularly in Anjou, Saint-Léonard, Rosemont, and Mercier, rear balconies often serve several purposes. A poorly positioned outdoor unit can block a door, restrict access to a staircase, or create a dangerous contact point.
We therefore measure the available space before confirming the model and support type.
An orientation that directs the discharged air toward the outside
In the photograph, the rear coil of the heat pump is visible from the passageway. The ventilation side faces the guardrail and the open space beyond the balcony.
This orientation is important. Air discharged by a heat pump must not be directed immediately toward a brick wall or an obstacle that is too close. Poor orientation can cause air recirculation, reduce the unit’s efficiency, and increase operating strain.
Here, the air can be discharged toward the outside of the balcony, where much more space is available.
The coil also retains access to the surrounding air. Since the unit is installed in a confined space, we must ensure that the appliance’s two fundamental functions remain possible:
- draw in enough air through the heat exchanger;
- discharge the treated air without immediately reintroducing it into the machine.
This check is essential in both cooling and heating modes.
Why we used a raised metal support
The Hitachi unit rests on a metal structure installed directly on the balcony floor. This structure raises the unit by several dozen centimeters.
The choice of support is not based solely on visual preference.
Reducing snow-related risks
A rear balcony can accumulate snow blown by the wind, even when it is partially protected by neighboring buildings. A unit installed too low could have its base, coil, or openings partially obstructed.
The height of the support helps keep the equipment above usual accumulations and makes it easier to clear snow around the heat pump.
Promoting defrost-water drainage
In heating mode, the outdoor unit must periodically run a defrost cycle. The resulting water may fall beneath the unit and then freeze when the outdoor temperature is low.
Clearance beneath the heat pump allows this water to drain away rather than immediately forming a block of ice upon contact with the base.
On a balcony, this point requires particular attention. Water must not be directed toward a door, staircase, or passageway where it could create a slippery surface.
Protecting the wooden floor
The support distributes the weight of the unit across four contact points. It also keeps the unit’s metal and refrigeration components away from the floor.
Before such an installation, the condition of the balcony must be checked, and its structure must be confirmed to be stable enough to support the unit and its support. We avoid assuming that a balcony is automatically suitable simply because it appears visually solid.
Anti-vibration supports to limit noise transmitted to the building
Anti-vibration pads are visible between the outdoor unit and the metal support.
This precaution is particularly important on a wooden balcony. Unlike a concrete slab on the ground, a balcony structure can act as a resonance chamber. A slight vibration from the compressor can then be transmitted to the floor, wall, or nearby rooms.
The supports help reduce rigid contact between the heat pump and its supporting structure. They therefore help reduce:
- vibrations felt on the balcony;
- resonances in the boards;
- noise transmitted indoors;
- the movements caused by compressor starts and variations.
The support must also be perfectly stable. Anti-vibration pads cannot correct an improperly leveled structure or an appliance that rocks.
A direct connection through the brick wall
The refrigerant piping route was kept as short and direct as the building configuration allowed.
The insulated lines exit the brick wall near the outdoor unit, limiting the visible sections on the balcony. The communication cable and power supply are organized near the unit, while an electrical device is installed on the wall.
This arrangement offers several advantages:
- fewer lines exposed to the elements;
- reduced bulk;
- lower risk of contact with occupants;
- easier access to the connections;
- more discreet exterior finish.
The masonry opening must be prepared carefully. A poorly sealed opening can allow water, air, insects, or moisture to enter the wall.
We must therefore protect the penetration point, maintain the required slope when gravity drainage is used, and prevent the lines from rubbing directly against the brick.
The Hitachi airHome Multi dual-zone configuration
In the Hitachi airHome Multi RAM-G-N-HAA range, the model designed for two indoor connections is the RAM-G18N2HAA.
The manufacturer's technical data sheet indicates the following for this dual-zone configuration:
- 18,000 BTU/h of rated cooling capacity;
- 22,000 BTU/h of rated heating capacity;
- cooling modulation from 7,000 to 20,500 BTU/h;
- heating modulation of up to 24,000 BTU/h with a ductless combination;
- a TRÉS2 rating of up to 23,0;
- a CPSC2 Region 5 rating of up to 7,85;
- a heating range down to -20 °C;
- an advertised outdoor sound level of 52 dB(A) at high speed;
- a 208–230 V, single-phase, 60 Hz power supply;
- a minimum circuit ampacity of 16 A;
- a maximum overcurrent protection of 25 A.
Page 4 of the brochure also indicates a maximum total piping length of 165 feet for the dual-zone model, a maximum length of 82 feet between the units, and two 1/4-inch liquid connections with two 3/8-inch gas connections.
The exact performance of an installation always depends on the actual combination of indoor units. Knowing the outdoor model alone is not enough: the capacities, efficiencies, and certifications must be validated using the complete references for the connected units.
Two zones do not necessarily mean two identical units
One of the benefits of a Hitachi airHome Multi system is the ability to adapt each indoor unit to the room it serves.
The product line includes, among other options:
- airHome 400 wall-mounted units;
- airHome 650 wall-mounted units;
- airHome Floor floor consoles;
- airHome Ducted units;
- airHome mini-cassettes.
Available indoor capacities generally range from 7,000 to 24,000 BTU/h, depending on the format.
In an Anjou residence, one zone may correspond to an open-concept area requiring a higher airflow rate, while the second may be a bedroom or office requiring a smaller, quieter unit.
We determine the capacity of each zone by evaluating, among other factors:
- the room dimensions;
- sun exposure;
- the amount of glazing;
- the ceiling height;
- the insulation;
- the floor;
- the proximity of the kitchen;
- the number of occupants;
- the opening toward adjoining rooms.
An oversized indoor unit does not automatically improve comfort. It can reach the setpoint too quickly, reduce dehumidification, and create more pronounced temperature variations.
The details that make a difference in a Montreal balcony HVAC installation
Avoid mounting directly on an old brick wall
In some projects, an outdoor unit can be installed on wall-mounted brackets. This choice is not always appropriate for an old brick building.
A wall-mounted bracket can transmit more vibration to the structure and requires sufficiently strong masonry. On an accessible wooden balcony, a freestanding support can offer a more practical solution, provided that the floor and its structure are adequate.
The support used here also makes it possible to remove or relocate the unit during major work without having to dismantle anchors in the brick.
Preserve access to the coil
The outdoor coil must be accessible for inspection and cleaning. Leaves, dust, tree seeds, and urban debris can accumulate between the fins.
The balcony opens directly onto mature trees, as can be seen in the image. This setting makes seasonal inspection particularly relevant.
The owner should avoid storing objects directly against the unit. Bins, furniture, bags, and decorative panels can reduce airflow or make maintenance more difficult.
Monitor defrosting in winter
With a ground-level installation, defrost water usually falls onto a slab or a draining surface. On a balcony, its path should be monitored during the first cold spells.
Occupants must keep the space beneath the unit clear and remove ice buildup before it reaches the base of the heat pump.
Never break the ice by striking the unit or the refrigerant lines. When the buildup becomes abnormal, an inspection can determine whether the drainage, positioning, or operation of the unit needs to be checked.
Do not block the discharge with a tarp or screen
Some homeowners want to completely conceal the outdoor unit with a decorative screen. On a balcony this narrow, such a modification could severely hinder airflow.
A screen should never be added without verifying the clearances required by the manufacturer. The heat pump needs a much greater volume of air than the size of its fan might suggest.
Hitachi indoor unit maintenance
Depending on the indoor model selected, the airHome Multi range may offer FrostWash, Mold Guard, PM2.5 activated carbon filtration, or the ViroSense S filter.
FrostWash uses a freezing and thawing process to help clean the indoor coil. Mold Guard circulates air for approximately 60 minutes after certain cooling or dehumidification operations to dry the internal components.
These features make it easier to keep the unit clean, but they do not replace:
- regularly cleaning the filters;
- inspecting the drain;
- professional deep cleaning when necessary;
- inspecting the outdoor coil;
- checking the connections and overall operation.
Equipment warranty and registration
The Hitachi brochure presents a standard seven-year warranty on the compressor and a five-year warranty on parts. An extended ten-year warranty on the compressor and parts may be offered for certain residential installations after online registration.
Enhanced protection is also offered, with coverage of up to twelve years on the compressor, ten years on parts, and ten years on labour, subject to registration and purchase of the applicable upgrade.
Warranty conditions must always be confirmed for the installed combination. System registration should not be delayed, as a delay or missing information may affect the available coverage.
Eligibility for financial assistance
Hitachi documentation indicates that the product line is eligible for several provincial heat pump incentives. However, this statement does not guarantee that a specific installation will automatically receive financial assistance.
Eligibility may depend on:
- the outdoor model number;
- the indoor unit references;
- the certified combination;
- the capacity at a given temperature;
- the building;
- the program in effect;
- the purchase and installation date;
- the documents submitted with the application.
At AirGreen, we always distinguish between the advertised commercial performance and the combination officially recognized by the relevant program.
An installation designed for the building, not just the machine
The result of this Anjou project is a dual-zone multi-zone heat pump integrated into a space where a conventional ground installation was not possible.
The outdoor unit is:
- installed on a stable metal support;
- elevated above the balcony;
- mechanically isolated with anti-vibration mounts;
- oriented toward the open space;
- positioned without completely blocking the passage;
- connected directly through the wall;
- accessible for inspection and maintenance.
This project illustrates our approach to air conditioning and heating projects in Montréal. We do not select a location simply because the unit can physically fit there. We analyze ventilation, vibrations, drainage, circulation, electrical requirements, the piping route, and future maintenance.
We apply the same rigor to our installations in Anjou, Saint-Léonard, Mercier, Montréal-Nord, Laval, Longueuil, on the North Shore and on the South Shore.
A Hitachi airHome Multi heat pump can provide two comfort zones with a single outdoor unit, but its success depends directly on the quality of the planning. On a narrow balcony, every clearance and support point matters.