Two independent systems integrated into an older façade with an orderly outdoor installation
This installation of Hitachi airHome 800 wall-mounted heat pumps in Sainte-Julie illustrates a common situation in plexes, multigenerational homes, and buildings with multiple living areas: choosing a high-performance appliance is not enough. It is also necessary to find a durable outdoor location, maintain the required clearances, protect the refrigerant lines, and avoid obstructing the windows, access points, and elements already present on the façade.
At this site, we installed two Hitachi airHome 800 outdoor units side by side on a façade with several visible constraints: an exterior metal staircase, a gallery, windows at different levels, a basement opening, and relatively limited working space. The goal was to achieve a clean, stable, and easy-to-maintain installation without further cluttering this part of the building.
The two heat pumps were placed on individual metal supports, which were themselves installed on solid slabs. This configuration raises the appliances above the ground, reduces their exposure to moisture, and facilitates the drainage of water produced during defrost cycles.
A layout designed for two outdoor units
When two wall-mounted heat pumps must be installed on the same façade, their positioning must be planned as a whole. Poor placement can complicate maintenance, restrict airflow, or create a tangle of lines and cables.
For this project in Sainte-Julie, we chose a parallel arrangement that offers several advantages:
- The units remain accessible for maintenance and repairs;
- Each appliance rests on its own support;
- The lines are grouped inside line-hide covers;
- The basement window remains unobstructed;
- The appliances do not rest directly on the ground;
- The façade retains a structured appearance despite the presence of two systems.
The left unit was placed under the gallery, in an area where the available height allowed sufficient clearance around the appliance. The right unit was positioned beneath the large ground-floor window while keeping access to the small basement window.
This coordination is particularly important in an existing building. Unlike new construction, we must work around the placement of openings, electrical drops, existing lines, wall finishes, and exterior structures already in place.
Elevated supports suited to South Shore winters
The outdoor units are installed on metal supports secured to stable bases. This elevation serves a practical purpose during Quebec winters.
A heat pump used for heating extracts heat from the outdoor air. When conditions favor frost formation, the unit periodically performs a defrost cycle. The resulting water must be able to drain beneath the unit without forming a block of ice against the coil or chassis.
An installation that is too low can lead to several problems:
- snow accumulation in front of the heat exchanger;
- partial obstruction of the air intake;
- ice formation beneath the unit;
- reduced space available for maintenance;
- prolonged contact with ground moisture;
- premature deterioration of an improperly prepared base.
In Sainte-Julie, as elsewhere on the South Shore, the support height must be selected based on the usual snow accumulation, the layout of the land, and wind exposure. It is also important to anticipate what will happen when snow is shoveled or moved around the building.
The slabs visible beneath the supports help distribute the weight and maintain a more uniform base. An outdoor unit should not simply be placed on soft ground that could settle after several freeze-thaw cycles.
A protected and visually consistent piping route
The refrigerant lines, communication cables, and certain sections of the drainage system were placed in rigid pipe covers installed horizontally on the façade. These covers protect the components from impacts, sunlight, and the elements, while considerably improving the appearance of the installation.
In the project photo, the pipe covers follow a continuous line above the outdoor units. This method avoids creating multiple irregular routes on the wall.
These covers generally contain:
- the liquid line;
- the refrigerant gas line;
- the pipe insulation;
- the communication wiring;
- the power cable, depending on the configuration;
- the condensate drain when it follows the same route.
Insulation quality is essential. An improperly insulated line can produce condensation, reduce efficiency, or leave moisture marks on the façade. The joints of the line-hide covers must also be assembled carefully to reduce water infiltration and prevent insects from reaching the openings made in the wall.
An older façade requires more careful preparation
The building has a stucco exterior finish as well as several transitions between different siding materials. In this context, drilling must be carried out precisely to avoid unnecessarily weakening the surface.
Before running the lines, we must check, among other things:
- the wall thickness;
- the possible presence of wires or pipes;
- the location of the studs;
- the slope required for the drain;
- the position of the indoor unit;
- the shortest and most logical route to the outdoor unit.
The opening must then be insulated and sealed on both sides. This sealing helps prevent air infiltration, moisture, and insects from entering. In a professional HVAC installation, this detail matters just as much as the alignment of the units.
We also pay attention to the slope of the drain lines. An inadequate slope can cause water to back up toward the indoor unit, especially during hot and humid days when the air conditioner removes a significant amount of moisture from the air.
Why the Hitachi airHome 800 is suitable for Sainte-Julie's climate
The Hitachi airHome 800 is a wall-mounted heat pump designed to provide cooling, heating, and indoor air treatment. The series is available in several capacities, from 9,000 to 24,000 BTU/h, making it possible to adapt the unit selection to the size, insulation, sun exposure, and layout of each space.
Capacity should not be selected solely based on the number of square feet. In a plex, two units of comparable size may have different needs because of their floor, number of exterior walls, windows, or insulation quality.
Heating designed to operate down to -30 °C
The airHome 800 series can operate in heating mode when the outdoor temperature drops as low as -30 °C. The manufacturer also indicates that the unit can maintain up to 100% of its heating capacity at -20 °C, depending on the model selected.
This performance is particularly relevant for an installation in Sainte-Julie, where the heat pump must continue providing heat throughout much of the winter, not only during the milder temperatures of fall.
The system offers efficiency of up to:
- 26.5 TRÈS2;
- 9.7 CPSC2 for climate region 5;
- a heating range extending down to -30 °C;
- a cooling range starting at approximately -20 °C;
- an indoor sound level as low as 30 dB(A) on the lower-capacity models.
Exact values vary according to the unit's capacity. For example, the 9,000, 12,000, 18,000, and 24,000 BTU models have different capacities, dimensions, airflow rates, and electrical requirements. The manufacturer's technical specifications also indicate the use of the refrigerant R32, the required refrigerant connections, and heating capacities at -8 °C, -15 °C, -20 °C, -25 °C, and -30 °C.
Inverter technology reduces temperature fluctuations
Inverter technology allows the compressor to adjust its speed according to the room's actual needs. Rather than operating only at full capacity before shutting down completely, the heat pump modulates its operation.
This modulation provides several benefits:
- more stable indoor temperature;
- fewer abrupt starts;
- generally quieter operation;
- energy consumption better matched to demand;
- better humidity control in summer.
In a building with multiple occupants or zones, this stability improves comfort without imposing the same setting on the entire building. Each system can be controlled independently according to the use of the room or dwelling it serves.
FrostWash 3.0 and Mold Guard 2.0 to keep the indoor unit cleaner
The airHome 800 incorporates several features that go beyond heating and cooling.
The FrostWash 3.0 technology cools the heat exchanger to form a layer of ice that traps some of the accumulated dust and contaminants. The ice then melts and carries these particles toward the drain.
The Mold Guard 2.0 system monitors conditions inside the unit, even when it is turned off. When conditions favorable to mold formation are detected, the system can heat the indoor coil to dry it.
These functions do not replace regular HVAC maintenance. Filters must still be cleaned, the drain must be checked, and the heat exchanger must be inspected. However, they help limit residual moisture and dirt buildup between maintenance visits.
PM2.5 filtration and air quality control
The indoor unit includes a PM2.5 activated carbon filter as well as a stainless-steel prefilter. According to the tests presented by the manufacturer, the filter can remove a high proportion of fine particles under controlled conditions.
Activated carbon also helps reduce certain odors and volatile organic compounds. This feature may be useful in a home located near a busy road, in a house with pets, or in a space where cooking odors circulate easily.
It remains important to understand that a wall-mounted heat pump primarily recirculates the room’s air. It does not replace an air exchanger or a ventilation system that introduces outdoor air.
Wi-Fi, airCloud Go, Smart Eco, and SleepSense
The Wi-Fi interface for the airCloud Go app is included and can be discreetly installed inside the unit. Occupants can therefore adjust the temperature, view certain settings, and schedule operation remotely.
The available functions include:
- weekly scheduling;
- remote control;
- integration with Amazon Alexa and Google Home;
- the display of certain error codes;
- the estimation of energy consumption;
- the activation of certain self-cleaning functions;
- the Smart-Fence function linked to the user’s position.
The Smart Eco mode uses a motion sensor to detect when the room is unoccupied. After a period of inactivity, the heat pump gradually reduces its energy consumption, then returns to the initial setting when the occupants return.
The SleepSense function adjusts operation during the night to limit temperature variations that may interfere with sleep.
Adaptive defrosting and outdoor unit protection
The Hitachi heat pump uses adaptive defrost technology. The system initiates defrosting according to actual conditions rather than relying solely on a fixed timer.
Properly controlled defrosting helps maintain heat exchange while avoiding unnecessary cycles. During defrosting, it is normal to see steam or water beneath the outdoor unit. This is precisely why preparing the base and determining the height of the supports are important.
The manufacturer also offers a snow protection accessory for highly exposed locations. This accessory must be selected according to the building’s actual configuration and must not block airflow.
R32 refrigerant and special installation requirements
The airHome 800 series uses R32 refrigerant, which has a lower global warming potential than several refrigerants used in older generations of heat pumps.
Using R32 requires appropriate tools, procedures, and training. The connections must be prepared precisely and then tested before commissioning.
A complete installation includes, among other things:
- proper cutting and flaring of the lines;
- tightening to the recommended torque;
- a leak test;
- a sufficiently deep vacuum;
- vacuum stability verification;
- opening the service valves;
- a cooling and heating test;
- drainage inspection;
- temperature and pressure validation;
- equipment registration when required.
Failing to evacuate the system or merely purging the lines with refrigerant can leave air and moisture in the circuit. This practice reduces compressor reliability and does not constitute a professional installation.
Electrical Requirements by Capacity
Electrical requirements vary according to the selected model. According to Hitachi documentation, the 9,000 and 12,000 BTU models use a 230 V power supply with a minimum circuit ampacity of 14 A and maximum protection of 25 A. The 18,000 and 24,000 BTU models specify a minimum circuit ampacity of 20 A and maximum protection of 35 A.
The circuit breaker must never be selected solely based on the nominal capacity expressed in BTUs. We must follow the MCA and MOP values listed on the outdoor unit’s nameplate and in the technical documentation.
The wiring, disconnect switch, and overcurrent protection must comply with the Quebec Construction Code and the manufacturer’s requirements.
Financial Incentives and AHRI Number Validation
The airHome 800 documentation indicates that the series qualifies for several provincial heat pump incentives. In Quebec, however, actual eligibility depends on the complete model, the AHRI number, the heating capacity at the reference temperature, and the rules in effect when the application is submitted.
Before providing an estimate, we verify, among other things:
- the exact indoor and outdoor model;
- the corresponding AHRI number;
- the type of residence;
- the primary heating system;
- the capacity recognized by the program;
- the purchase and installation date;
- the required documents and photographs.
We avoid guaranteeing an amount based solely on the appliance’s trade name. Two models in the same series may qualify for different amounts.
Hitachi Warranty and Equipment Registration
The Hitachi brochure states a standard warranty of seven years on the compressor and five years on parts. For certain residential installations, online registration makes it possible to obtain an extended warranty of ten years on the compressor and ten years on parts, subject to the manufacturer’s terms.
Enhanced protection may also be available with advertised coverage of up to twelve years on the compressor, ten years on parts, and ten years on labor when an eligible upgrade is purchased.
Registration must be completed within the specified time frame. The owner should keep:
- detailed invoice;
- model numbers;
- serial numbers;
- AHRI certificate;
- proof of registration;
- documents relating to additional warranties.
Mistakes to avoid in a similar installation
An installation involving two outdoor units on the same façade must avoid several common mistakes.
Installing the units too close to the ground
This mistake increases the risk of snow obstruction and ice formation beneath the units.
Blocking a window or service access
The units must be positioned to allow servicing without unnecessarily blocking an opening in the building.
Crossing lines without planning
An improvised route makes the installation look less polished and can add unnecessary lengths of piping.
Neglecting drainage
The indoor drain must maintain a continuous slope. Outdoor defrost water must also be able to drain away without damaging the foundation or creating a dangerously icy surface.
Installing two units too close together
Each unit must have the necessary space to draw in and discharge air. Manufacturer clearances must be respected even when a tighter arrangement appears visually appealing.
Failing to verify the existing structure
A staircase, balcony, or aging façade should not be used as an attachment point without verification. Heat pump supports must rest on a suitable, independent base when the configuration requires it.
A method applied in Sainte-Julie and throughout Greater Montreal
This project reflects how we approach wall-mounted heat pump installations in Sainte-Julie, as well as in Montreal, Laval, Longueuil, on the North Shore, and on the South Shore.
We do not limit our analysis to the choice of brand or the number of BTUs. We also assess access, the building structure, drainage options, electrical supply, outdoor airflow, and future maintenance needs.
In the case presented, the alignment of the two Hitachi units, the elevated supports, the individual bases, and the protected routing of the lines make it possible to integrate two independent systems on a façade already crowded with several architectural elements.
The result is a functional and orderly HVAC installation, suited to Sainte-Julie’s winter conditions and designed to preserve access to the equipment throughout its service life.