Installing a heat pump high up in a narrow backyard without sacrificing access, stability, or finish quality
This Hitachi airHome 800 wall-mounted heat pump installation completed in Baie-D’Urfé perfectly illustrates a common challenge in the West Island of Montréal: finding a functional outdoor location on a property with limited ground space, while protecting the unit from snow and maintaining a neat appearance on a brick façade.
At this residence, the outdoor unit could not simply be placed on a ground-level slab. The available area was in a relatively narrow backyard, surrounded by masonry walls, windows, and elements used daily by the occupants. We therefore chose an elevated installation on a sturdy wall-mounted structure secured to the brick.
The photograph shows several important details of the project: the Hitachi unit is supported by two braced triangular brackets, the electrical disconnect is installed nearby, the connections are grouped on the side of the unit, and vibration-dampening elements separate the heat pump from its metal support.
The result is a compact HVAC installation that frees up ground-level walking space and provides greater protection for the equipment against winter accumulation.
Why mount the outdoor unit so high?
In Baie-D’Urfé, as in several areas of Montréal, Laval, Longueuil, the North Shore, and the South Shore, snow must be considered when choosing the location. An outdoor unit placed too close to the ground can quickly become surrounded by naturally accumulated snow, windblown snow, or snow moved during clearing.
In heating mode, the heat pump must draw in and discharge a substantial volume of air. If the rear grille or sides are blocked, heating capacity decreases and the system may initiate defrost cycles more frequently.
An elevated wall-mounted installation offers several advantages:
- it keeps the outdoor coil above a large portion of accumulated snow;
- it frees up the terrace or yard;
- it reduces the risk of impact caused by objects moved along the ground;
- it facilitates the drainage of water produced during defrost cycles;
- it keeps the unit’s base away from leaves, dirt, and certain splashes;
- it sometimes makes it possible to shorten the refrigerant line between the units.
However, the height must never be chosen arbitrarily. A heat pump installed at a height must remain accessible for maintenance, repairs, and possible replacement. It must also not block a window, encroach on an opening, or discharge air directly toward an area that could be uncomfortable for occupants.
For this project, we used the section of wall above a lower projection while keeping the unit clear of the main windows visible on the façade.
A triangulated wall structure suited to the weight of the equipment
The outdoor unit in the Hitachi airHome 800 range is not lightweight equipment. Depending on the capacity, its net weight ranges from approximately 91 lb for the 9,000 and 12,000 BTU/h versions to more than 160 lb for the 18,000 and 24,000 BTU/h versions. Dimensions and weight therefore vary considerably from one model to another.
The support must be selected and fastened with consideration for:
- the static weight of the machine;
- compressor and fan vibrations;
- the forces exerted by the wind;
- freeze-thaw cycles;
- the condition of the masonry;
- the depth and type of anchoring;
- the space required for the connections;
- future maintenance operations.
The photograph shows two long metal brackets reinforced with diagonal elements. This triangulated geometry transfers the load to several points on the wall rather than concentrating it solely at the base of the unit.
We pay particular attention to the mortar joints and the condition of the brickwork. A heat pump support must not be fastened randomly to an aging façade. Each anchor point must contribute to a stable, level structure suited to the actual weight of the installed model.
Anti-vibration supports between the unit and the brackets
Isolators are visible at the contact points between the heat pump and its supports. Their function is to reduce the transmission of mechanical vibrations to the building structure.
This element is particularly important when the outdoor unit is installed on a brick wall adjacent to occupied spaces. Without adequate insulation, a slight vibration outside can be amplified by the masonry and become noticeable indoors, especially at night when ambient noise decreases.
To limit this phenomenon, we check:
- that the unit rests evenly on its supports;
- that the bolts are tightened without unnecessarily crushing the isolators;
- that the lines are not under tension;
- that no rigid pipe comes into direct contact with the brick;
- that the enclosure does not vibrate against a metal component;
- that the fan runs without unusual noise after startup.
An inverter heat pump continuously modulates its speed. Its behavior must therefore be observed at different operating speeds, not only during the first few seconds after startup.
A methodically planned work-at-height operation
This installation required work at height in a yard where maneuvering space was limited. The presence of windows, a lower overhang, and exterior accessories required our team to plan access before lifting the unit.
Lifting and securing a heat pump on wall brackets requires rigorous coordination. The unit must be positioned without damaging:
- the heat exchanger fins;
- the fan grille;
- the casing;
- the refrigerant valves;
- the service fittings;
- the freshly installed supports.
Whenever possible, we prepare the brackets, anchors, and protective components before the unit arrives at its final position. This organization reduces the time the appliance must be handled at height and limits improvised movements.
Connections grouped on the side of the system
On the right side of the unit, the refrigerant lines and electrical connections form a controlled loop before reaching the building. This extra length should not be confused with a randomly routed path. It prevents excessively tight bends in the copper pipes and reduces stress on the service valves.
The line size depends on the exact model. In the airHome 800 range:
- the 9,000 and 12,000 BTU/h versions use 1/4 in. fittings for the liquid line and 3/8 in. fittings for the gas line;
- the 18,000 BTU/h version uses 1/4 in. and 1/2 in. fittings;
- the 24,000 BTU/h version uses 3/8 in. and 5/8 in. fittings.
Installing the wrong pipe diameter can impair oil return, refrigerant flow, and compressor reliability. We therefore always verify the exact combination of the indoor and outdoor units before preparing the lines.
The exposed sections are protected against ultraviolet rays, moisture, and mechanical damage. Deteriorated outdoor insulation may lose its effectiveness and allow condensation to form on the cold line during the summer.
An electrical disconnect installed nearby
The gray enclosure visible to the right of the unit is the outdoor electrical disconnect. It allows the power supply to be shut off locally during maintenance or repairs, without relying solely on the indoor electrical panel.
Its location must remain accessible, but it must not block the heat pump’s service panels or be positioned directly in the air discharge.
The required electrical circuit varies with the capacity of the airHome 800. The 9,000 and 12,000 BTU/h models have a minimum circuit ampacity of 14 A and maximum overcurrent protection of 25 A. The 18,000 and 24,000 BTU/h models specify a minimum circuit ampacity of 20 A and maximum overcurrent protection of 35 A.
These values show why the circuit breaker must not be selected solely based on the number of BTUs. The nameplate, the manufacturer’s instructions, and the applicable electrical requirements must be verified for each installation.
Defrost water: an essential detail on a wall-mounted unit
In heating mode, the outdoor coil becomes cold and may accumulate frost. The heat pump periodically initiates a defrost cycle to melt this buildup.
The water produced then drains through the base of the unit. With a wall-mounted bracket like this one, it is necessary to examine what is directly beneath the unit. The water must not fall onto a walkway where it could form a sheet of ice, nor accumulate against a window, door, or sensitive building component.
We therefore pay attention to:
- to the clearance beneath the unit;
- to the slope of the lower surfaces;
- to the risk of splashing against the brick;
- to the possibility of ice formation;
- to the access required to remove a winter accumulation.
We also recommend never building an enclosed enclosure around the unit to protect it from snow. An improperly designed shelter can restrict airflow and recirculate the cold air discharged by the unit.
Performance, comfort, and maintenance of the Hitachi airHome 800 installed in Baie-D’Urfé
A HeatForce heat pump designed for cold climates
The Hitachi airHome 800 HeatForce operates in heating mode down to an advertised outdoor temperature of −30 °C. The manufacturer also indicates a maximum capacity corresponding to 100% of the rated heating capacity at −20 °C, depending on the model combination.
At −30 °C, the heat pump continues to produce heat, but its capacity varies by size:
- 5,500 BTU/h for the 9,000 BTU/h model;
- 6,000 BTU/h for the 12,000 BTU/h model;
- 12,960 BTU/h for the 18,000 BTU/h model;
- 15,000 BTU/h for the 24,000 BTU/h model.
This information is crucial during sizing. The fact that a heat pump can operate at −30 °C does not automatically mean that it can cover all the building’s heat losses on its own during extreme cold.
At AirGreen, we compare the capacity actually available at low temperatures with the home’s needs. We take into account insulation, windows, floor area, number of stories, orientation, and the presence of supplemental heating.
An exact capacity that must be confirmed by the model number
The photograph identifies the Hitachi airHome 800 series, but the model number and capacity are not legible. We therefore avoid arbitrarily assigning a tonnage or BTU rating to this installation.
The range includes models marketed in the 9,000, 12,000, 18,000, and 24,000 BTU/h categories. The actual nominal cooling capacities are 9,500, 12,500, 18,000, and 22,000 BTU/h, respectively, while nominal heating capacities range from 12,000 to 25,400 BTU/h.
The appropriate choice depends more on the heating and cooling load than on floor area alone. Two similarly sized homes in Baie-D’Urfé may require different units because of their construction year, exposure to wind, or window quality.
Seasonal efficiency of up to 26.5 SEER2
The most efficient version in the range reaches up to 26.5 SEER2 for cooling and up to 9.7 Region 5 HSPF2. The values gradually decrease according to capacity but remain high for a wall-mounted heat pump designed for cold climates.
Inverter technology allows the compressor to adjust its speed to demand. Once the temperature has been reached, the appliance can reduce its output instead of shutting down completely and then restarting at full power.
This modulation promotes:
- more stable indoor temperature;
- generally quieter operation;
- better humidity management in summer;
- energy consumption matched to actual demand;
- fewer on-off cycles.
However, actual performance depends on the quality of the installation. A blocked outdoor unit, an incorrect refrigerant charge, or dirty indoor filters can limit the performance of an appliance that is highly efficient on paper.
An outdoor design built for durability
Hitachi’s documentation describes a fire-resistant, rust-proof metal cabinet as well as a blue anti-corrosion coating applied to the condenser. It also describes the DuraSpin and FrostWash functions, which are designed to reduce dust buildup on the outdoor unit.
However, these features do not eliminate the need for periodic inspection. In a yard surrounded by vegetation and masonry like the one shown in the photograph, leaves, debris, and dust can reach the coil.
We recommend keeping the area around the unit clear and avoiding:
- to lean objects against the bracket;
- to let plants grow on the heat exchanger;
- to direct a high-pressure water jet at the fins;
- to install a waterproof cover during the winter;
- to place accessories on top of the unit.
FrostWash 3.0, Mold Guard 2.0, and indoor filtration
Inside the residence, the airHome 800 incorporates several features focused on keeping the heat exchanger clean.
FrostWash 3.0 uses a heating, freezing, and thawing sequence to loosen some of the accumulated contaminants. Mold Guard 2.0 monitors conditions inside the unit when it is turned off and can dry the coil when the system detects an environment conducive to mold formation.
The series also includes a PM2.5 activated carbon filter and a stainless steel prefilter. The documentation also states that the airCloud Go app allows users to activate certain cleaning functions and display error codes.
These technologies make it easier to manage the unit, but they do not replace proper HVAC maintenance. The filters must be cleaned, and the condition of the fan, condensate pan, and heat exchanger must be checked periodically.
Wi-Fi control with airCloud Go
The Wi-Fi interface for the airCloud Go app is included with the series. The owner can manage the temperature remotely, schedule weekly programs, view an energy estimate, and receive certain operating information.
The Smart Eco, Smart-Fence, and SleepSense features allow operation to be further adapted to the home's occupancy.
This connected management is particularly useful for a residence whose occupants are regularly away. The temperature can be checked or adjusted without leaving the system completely turned off during a period of hot or cold weather.
Equipment warranty and registration
The Hitachi brochure indicates a standard seven-year warranty on the compressor and five years on parts. A ten-year extended warranty on the compressor and parts is indicated for eligible residential installations when online registration is completed. An enhanced option offering twelve years on the compressor, ten years on parts, and ten years on labor is also presented under certain conditions and with the purchase of the corresponding upgrade.
It is essential to keep:
- itemized invoice;
- model numbers;
- serial numbers;
- installation date;
- proof of registration;
- documents relating to any additional warranty.
A warranty does not replace maintenance, and its terms may depend on the type of use, registration and compliance with the manufacturer’s conditions.
LogisVert financial assistance: verify the exact combination
Hydro-Québec’s residential LogisVert program currently provides assistance of $50 per 1,000 BTU/h of heating capacity at −8 °C for an ENERGY STAR-certified heat pump, or $120 per 1,000 BTU/h at −8 °C when it meets the criteria for a cold-climate heat pump. The total amount for this measure may reach $6,700, subject to all conditions.
For units installed on or after November 26, 2025, Hydro-Québec requires, among other things, ENERGY STAR certification. The amount must be verified using the complete model number or AHRI number in the official tool, and the application must generally be submitted within nine months of installation.
Hitachi documentation indicates that the airHome 800 is eligible for most provincial incentives, but this general indication does not automatically confirm the applicable amount for each combination.
We therefore verify the indoor model, outdoor model and certified combination before announcing any financial assistance. The commercial capacity of 12,000 or 18,000 BTU/h must not be used on its own to calculate the rebate.
Commissioning that confirms the work performed
Once the mechanical and electrical installation is complete, our work does not end when the power is turned on. Commissioning includes, among other things:
- inspecting the anchors and supports;
- checking that the unit is level;
- checking the refrigerant connections;
- evacuating the lines;
- checking that the vacuum holds;
- testing in cooling and heating modes;
- observing the fan and vibrations;
- checking the indoor drainage;
- checking communication between the units;
- explaining the controls to the owner.
This Hitachi airHome 800 wall-mounted heat pump installation in Baie-D’Urfé demonstrates that a narrow backyard or a façade with several openings is not necessarily an obstacle. Careful analysis makes it possible to create a raised, stable and accessible setup that frees up ground space while protecting the unit from winter conditions.
At AirGreen, we adapt each project to the building, whether it is located in the West Island, Montréal, Laval, Longueuil, the North Shore or the South Shore. Sizing, wall structure, line protection and commissioning are treated as the different parts of a single installation, not as separate jobs.