Installation of a Hitachi airHome 600 wall-mounted heat pump in La Prairie, on Montreal’s South Shore

A high-mounted outdoor unit on a brick façade requires careful planning

This wall-mounted heat pump installation in La Prairie presents a configuration that is very different from a residential project where the outdoor unit can simply be placed on a slab at ground level. Here, the rear brick façade, the height of the windows, the available space, and the route of the lines required a precise wall-mounted solution: securing the Hitachi airHome 600 outdoor unit directly to the masonry, at a sufficient height to preserve the area at the base of the building.

The project photo shows a narrow inner courtyard bordered by brick walls several stories high. The Hitachi unit is positioned in the upper part of the façade, to the right of a window, on a wall-mounted metal bracket. This choice clears the ground while keeping the unit in a relatively open area for air discharge.

Such an arrangement may seem simple once the work is complete. In practice, it requires more preparation than a conventional ground installation. We must take into account the strength of the masonry, the weight of the unit, vibrations, access at height, clearance around the fan, and the possibility of carrying out future HVAC maintenance without having to dismantle part of the installation.

Why install the outdoor unit up high?

In some properties in La Prairie, particularly multi-unit homes, older buildings, and residences with narrow yards, ground space is already being used for circulation, bins, patios, electrical equipment, or access to the units.

A high wall-mounted installation can then serve several purposes:

• preserve usable space in the yard;
• keep the heat pump away from snow accumulation;
• reduce the risk of impacts caused by objects or movement;
• prevent an appliance from blocking a passageway;
• move the unit away from areas where water may accumulate;
• facilitate a more direct route between the indoor unit and the outdoor unit.

In the case presented, the chosen position completely clears the lower part of the wall. The lines already present on the façade can therefore continue along their path without being obstructed by a heat pump placed on the ground.

A fastening system on brick that leaves no room for improvisation

The wall visible in the photo is made of brick. When an outdoor unit is installed on this type of façade, we cannot treat the masonry as a simple decorative surface. The support must properly transfer the weight and vibration forces to a sufficiently strong part of the building.

Anchor selection depends in particular on:

• condition of the brick;
• quality of the mortar joints;
• wall thickness and configuration;
• exact weight of the outdoor unit;
• length of the support arms;
• installation height;
• wind exposure;
• recommendations applicable to the fastening system.

A poorly anchored unit can gradually become misaligned, transmit vibrations to the structure, or place excessive pressure on certain bricks. At this height, a deficient fastening system also represents a major safety concern.

Our technicians must therefore identify the appropriate anchor points, keep the support perfectly level, and tighten each fastener according to the specified method. We also check that the support arms remain parallel and evenly support the unit base.

Managing vibrations on a rigid façade

A brick façade can transmit structural noise differently from an independent ground-mounted support. Even when a modern heat pump operates quietly, the compressor and fan produce slight mechanical vibrations.

When properly controlled, these vibrations generally go unnoticed. When a support is improperly installed, they can produce:

• a humming sound in an adjacent room;
• a noticeable resonance around a window;
• a metallic noise coming from the support;
• a vibration in the refrigerant lines;
• intermittent rubbing against the masonry.

To limit these problems, we check the rigidity of the support, the contact points, the positioning of the unit, and the layout of the lines. The pipes must not be stretched like cables or pressed directly against a surface that could amplify vibrations.

A position chosen near a window, without compromising operation

The heat pump is installed near a window but offset enough not to directly block the visible opening. This proximity still requires particular attention.

The outdoor unit's airflow must not be directed toward an opening in a way that creates discomfort or undesirable recirculation. We must also avoid making future work on the window, its flashing, or its masonry impossible because of the heat pump.

We must maintain functional clearance around the unit to allow for:

• air intake through the heat exchanger;
• front air discharge;
• removal of the panels;
• access to the refrigeration fittings;
• inspection of the electrical connections;
• periodic cleaning of the outdoor coil.

The photo shows that the front fan remains largely exposed. This is essential, since the unit must be able to discharge air without immediately encountering a wall, grille, or other equipment.

The outdoor routing of the lines on a multi-story façade

In a high-mounted HVAC installation, the routing of the lines becomes a central element of the project. The refrigeration copper tubing, power or communication cable, and condensate drain must be routed between the two units while remaining protected.

On a brick façade, we generally aim to create a route that is:

• as direct as possible;
• compatible with the manufacturer's length limits;
• visually neat;
• protected against the elements;
• accessible for inspection;
• designed to prevent chafing;
• adequately supported to prevent sagging.

The presence of existing cables on the wall also makes coordination more important. We must neither crush these installations nor create a tangle that would complicate future work.

The importance of continuous drainage

The indoor unit produces water when operating in cooling or dehumidification mode. When this water is drained by gravity, the drain must maintain a continuous slope toward the outside.

An improper slope can cause:

• water accumulating in the drain;
• gurgling noises;
• odors rising back up;
• overflow at the indoor unit;
• damage to the wall or ceiling;
• the formation of contaminants in a stagnant pipe.

Outside, the discharge point must also be chosen so that water does not flow over a window, an entrance, an electrical cable, or an area that could become slippery.

Working at height in a narrow interior courtyard

Access is one of the main visible challenges of this installation in La Prairie. The façade is high, and the yard is enclosed by several walls. Handling the outdoor unit must therefore be planned precisely.

Before lifting the unit, we must confirm:

1. the technicians’ access route;
2. the lifting method;
3. the stability of the access equipment;
4. the area where the unit can be temporarily placed;
5. the exact position of the support;
6. the availability of the connections once the unit is secured.

The heat pump must not be lifted until the support is ready and has been inspected. Once the unit is in place, the technicians must still be able to connect the lines, perform the leak test, evacuate the system, and open the service valves.

This sequence avoids unnecessary handling near the windows and masonry. It also reduces the risk of damaging the condenser fins, cabinet, or connections.

Hitachi airHome 600: cold-weather performance, Inverter modulation, and easier maintenance

The Hitachi airHome 600 is a wall-mounted heat pump available in several capacities. The range includes models with nominal cooling capacities of 9,000, 12,000, 15,000, 18,000, and 22,000 BTU/h, with the last configuration belonging to the commercial category commonly marketed as 24,000 BTU/h.

The exact capacity of the unit installed in La Prairie cannot be confirmed from the photograph alone, since the nameplate is not legible. At AirGreen, we avoid assigning a capacity based solely on the apparent dimensions of the outdoor unit. The selection must be confirmed using the model numbers and, above all, the building’s heating and cooling requirements.

Performance suited to Quebec seasons

According to Hitachi documentation, airHome 600 models can operate in heating mode down to -25 °C and in cooling mode at outdoor temperatures of up to 46 °C. The series uses R32 refrigerant, includes a heater in the condensate pan, and offers efficiency ratings of up to TRÉS2 of 23 and CPSC2 Region 5 of 9.2, depending on capacity. The models listed in the technical data sheet are also ENERGY STAR certified.

These data are particularly relevant on the South Shore, where a heat pump must perform several functions over the course of the same year:

• heat during cold periods;
• maintain a stable temperature during the shoulder seasons;
• provide cooling during heat waves;
• remove some of the indoor humidity;
• adjust its capacity as demand decreases.

Inverter technology modulates the compressor speed. Instead of operating solely according to an on-and-off cycle at full capacity, the unit can reduce its output as the indoor temperature approaches the setpoint.

This modulation promotes more consistent comfort and reduces sudden temperature fluctuations. It is particularly beneficial in a bedroom, living room or home whose load varies throughout the day.

Rated capacity is only one part of sizing

Living area remains a useful indicator, but it is not enough on its own to choose a heat pump. We also take into account:

• of the year of construction;
• of the wall and attic insulation;
• of the window area;
• of solar exposure;
• of the number of floors;
• of the ceiling height;
• of the room layout;
• of air infiltration;
• of the existing heating system;
• of the area the wall-mounted unit actually needs to serve.

An oversized heat pump can cool the air very quickly without running long enough to properly control humidity. It can also cause temperature fluctuations and less consistent cycles.

Conversely, an undersized unit may run for long periods at high capacity and struggle to meet demand during the coldest or hottest periods.

Heating capacity gradually decreases as outdoor temperatures drop

Like all heat pumps, the Hitachi airHome 600 does not produce exactly the same amount of heat at all outdoor temperatures. The specification sheet lists different capacities at -8 °C, -15 °C, -20 °C and -25 °C for each model.

For example, depending on the selected capacity, maximum output at -25 °C varies considerably from one unit to another. This information must be compared with the home’s heating load, not just the number of BTUs indicated in the product name.

In some homes, the heat pump can meet most seasonal needs while working with supplemental heating during extreme conditions. In other configurations, it is chosen primarily to improve the comfort of a specific area of the building.

Defrosting must be accounted for during system design

In winter, outdoor moisture can form frost on the heat exchanger. The heat pump then runs a defrost cycle to clear the coil.

The airHome 600 series includes adaptive defrost technology and a heater in the condensate pan. These features facilitate frost management, but the unit’s location remains decisive.

In this project, the elevated position offers an obvious advantage: the appliance is far from snow accumulation on the ground. Nevertheless, it is important to check where the defrost water drains. It must not fall onto a walkway, a door, electrical equipment, or a surface where it could form a dangerous sheet of ice.

Why you should avoid installing the unit directly beneath a runoff area

When an outdoor unit is mounted on a wall, we examine the elements located above it:

• window ledge;
• flashing;
• gutter;
• downspout;
• cornice;
• deteriorated masonry joint;
• air conditioner or other appliance installed on the upper floor.

Water from a ledge or gutter can fall directly onto the heat exchanger and then freeze. In the photo of this project, the heat pump is offset from the neighboring window, which helps limit direct exposure to runoff from the ledge.

FrostWash and DuraSpin: functions that help keep heat exchangers clean

The Hitachi airHome 600 includes several technologies designed to limit the accumulation of contaminants.

The FrostWash 3.0 function of the indoor unit follows three main steps:

1. the coil is heated to help detach some particles;
2. it is cooled to form ice that traps the dirt;
3. the ice melts and carries away some of the contaminants.

The DuraSpin function temporarily reverses the fan’s rotation to help expel larger particles. The documentation also describes a FrostWash function for the outdoor unit.

These features can help maintain performance, but they do not make heat pump maintenance unnecessary. The filters should always be checked and cleaned, while the outdoor heat exchanger must remain free of leaves, dust, vegetation, and debris.

Filtration, mold protection, and dehumidification

The indoor unit includes a stainless steel pre-filter and a PM2.5 activated carbon purification filter. The mold protection function circulates air through the internal components and heats the coil after certain cycles to promote drying.

This feature is useful in a humid climate, particularly during the summers in La Prairie, Longueuil, and the other municipalities on the South Shore. However, it is primarily intended to limit conditions favorable to mold growth inside the unit; it does not replace professional cleaning when a system is already contaminated.

The Dry mode can also remove some of the humidity from the indoor air. The maximum stated capacity reaches up to 4 liters per hour on the largest-capacity model, while the other models have lower ratings.

Wi-Fi control and scheduling with airCloud Go

The Wi-Fi adapter is included in the configurations presented by Hitachi. The airCloud Go app notably allows you to:

• adjust the temperature remotely;
• set weekly schedules;
• view an estimate of energy consumption;
• use the compatible voice control;
• activate certain smart features;
• control the unit according to occupancy patterns.

A stable schedule is generally preferable to constant setpoint changes. An Inverter heat pump often delivers better results when it can modulate gradually rather than having to recover several degrees after an extended shutdown.

Common mistakes in a high wall-mounted installation

This project highlights several mistakes that we systematically seek to avoid.

Securing the unit based solely on the visually available space

An unobstructed location is not necessarily a good location. The wall’s strength, clearances, drainage, noise, and future access must be checked.

Placing the bracket too close to a window

The heat pump must not interfere with opening, replacing, or maintaining the window. Vibrations transmitted to the adjacent room must also be considered.

Neglecting the unit’s weight

Depending on the model, the net weight of the airHome 600 outdoor unit varies approximately from 75 to 163 lb. The bracket and its anchors must be selected accordingly.

Making the service valves inaccessible

The connections must remain accessible after installation. A technician must be able to perform a test, add instruments, or carry out maintenance without completely disconnecting the heat pump.

Failing to protect the lines

Outdoor insulation can deteriorate under exposure to ultraviolet rays and the elements. The lines must be organized and protected according to their route.

Using non-compliant copper diameters

The connections vary according to capacity. The 9,000 and 12,000 BTU/h models typically use 1/4 in. and 3/8 in., while larger models may require 1/2 in. or 5/8 in. for the gas line.

Commissioning: the invisible step that determines reliability

A well-executed outdoor installation is not enough. Before startup, we perform the technical operations required to protect the compressor and ensure system performance.

Our procedure includes, among other things:

1. precise preparation of the lines;
2. flaring the ends;
3. tightening the connections to the appropriate torque;
4. leak test;
5. removal of air and moisture;
6. vacuum-holding verification;
7. opening the valves;
8. startup;
9. temperature and drainage verification;
10. vibration and noise inspection.

Insufficient evacuation can leave moisture in the refrigeration circuit. Over time, this moisture can affect the oil, compressor, and internal components. Commissioning is therefore just as important as the visible wall mounting.

An installation representative of the constraints encountered on the South Shore

Installations in La Prairie, Brossard, Candiac, Saint-Constant, Saint-Lambert, and Longueuil often present constraints that differ from those encountered in a home with a large, open yard.

We regularly work with:

• brick façades;
• shared yards;
• units to be installed on the second or third floor;
• limited access;
• balconies;
• existing equipment;
• vertical line-set routes;
• particular aesthetic requirements.

We apply this same level of rigor to our projects in Montréal, Laval, on the North Shore, and on the South Shore. The heat pump may be identical, but the installation method must be adapted to each building.

For this installation in La Prairie, the result is based on one central decision: use the available height rather than cluttering the yard. The Hitachi airHome 600 outdoor unit was therefore integrated into the brick façade on a stable wall bracket, in an area where its fan remains unobstructed and the ground remains fully accessible.