A high installation in a space with a sloped ceiling that required millimetre-perfect planning
This wall-mounted heat pump installation in Saint-François, in eastern Laval, presented an immediately visible constraint: the indoor unit had to be installed very high on a wall, near a sloped ceiling and in a vertically difficult-to-access space.
The job-site photograph shows a configuration that does not resemble a standard wall-mounted installation above a door or in a living room with an eight-foot ceiling. Here, the Hitachi airHome 800 unit was positioned in the upper part of a tall architectural space, where access required a sufficiently long ladder, precise work at height, and good coordination among the technicians.
This placement decision was not based solely on aesthetics. In this type of space, the position of the heat pump directly affects:
- air circulation between levels;
- heating distribution;
- air-conditioning efficiency;
- perceived noise in occupied areas;
- the passage of the refrigerant lines;
- condensate drainage;
- future access for maintenance.
Our task was therefore to integrate the unit into the building's particular geometry while maintaining the necessary clearances around the indoor unit.
Why install the unit so high?
A wall-mounted heat pump generally draws in air through its upper section before cooling or heating it, then redistributes it through the louvers located in the lower section. The unit therefore needs sufficient space between its casing and the ceiling to avoid restricting air intake.
In this residence in Saint-François, the ceiling is sloped and forms a pronounced angle above the unit. We had to identify an area where sufficient overhead clearance was maintained across the entire width of the unit, without placing it too close to the junction between the two surfaces.
Installing the unit high up offered several advantages:
- the airflow could travel a greater distance across the room;
- the unit occupied wall space that would otherwise have been difficult to use;
- the casing remained away from furniture and walkways;
- cool air could naturally descend through the space;
- the perceived noise level near the occupants was reduced.
However, a very high installation also comes with additional responsibilities. Since warm air tends to rise, adjusting the louvers in heating mode becomes important. If the airflow is directed horizontally, some of the heat may remain near the upper part of the room. We therefore configure the unit to encourage downward airflow and better circulation in the occupied zone.
A more complex worksite access than it appears
The presence of the ladder in the photo helps convey the actual installation height. At this elevation, each step takes more time and requires greater control.
The technician must be able to:
- position and level the mounting plate;
- locate the studs or structure capable of supporting the unit;
- drill the wall opening at the correct angle;
- handle the indoor unit without damaging its casing;
- connect the drain and the lines;
- check the seal and condensate drainage;
- properly close the panels;
- carry out the operational tests.
The visible unit is photographed with its lower panel open, which corresponds to an installation or inspection stage. At this height, it is essential to properly finalize every connection before removing the access equipment. Revisiting a poorly planned detail several times unnecessarily increases the risks and the duration of the work.
At AirGreen, we prepare this type of HVAC installation in Laval by considering not only the unit's final location, but also how our technicians will be able to work safely around it.
Routing the lines through a uniquely shaped wall
A wall-mounted heat pump is connected to its outdoor unit by several components:
- a liquid refrigerant line;
- a gas refrigerant line;
- a communication cable;
- a power supply, depending on the configuration;
- a condensate drain.
In a room with a sloped ceiling, the shortest route is not always the best. Drilling must avoid structural elements, electrical cables, plumbing pipes, and areas where water could accumulate.
The drain is a particularly sensitive component. In air conditioning, moisture removed from the air turns into water in the drain pan of the indoor unit. This water must flow continuously outdoors or to a designated drainage point.
Whenever possible, we favor gravity drainage with a continuous slope. An improperly sloped drain can cause:
- draining noises;
- water buildup in the pipe;
- backflow toward the unit;
- water droplets on the wall;
- damage to the interior finish;
- the formation of deposits or odors.
In a high-mounted installation, the slope may seem easier to achieve, but the route is often longer and sometimes passes through several sections of the building. Planning must therefore be completed before permanently securing the unit.
A Hitachi airHome 800 suited to the winters of Saint-François
The Hitachi airHome 800 is an Inverter wall-mounted heat pump designed to provide cooling, heating, and several air-treatment functions.
The series includes capacities ranging from 9,000 to 24,000 BTU/h. The exact capacity installed on this project cannot be confirmed from the photograph alone; it depends on the indoor and outdoor models selected during sizing.
Depending on the capacity, the lineup can deliver efficiency ratings of up to 26.5 SEER2 and a region 5 HSPF2 of up to 9.7. It operates in heating mode down to -30 °C, and some models maintain their full rated capacity down to -20 °C. It also uses R32 refrigerant, which has a lower global warming potential than several older refrigerants.
These characteristics are particularly relevant in Saint-François, where a heat pump must contend with:
- extended periods of cold weather;
- freezing rain;
- defrost cycles;
- rapid temperature changes;
- summer humidity;
- hot days in spaces with high ceilings.
Inverter technology adjusts the compressor speed according to actual demand. Rather than operating only at full capacity and then stopping, the unit can modulate its output to maintain a more stable temperature.
Sizing does not depend solely on floor area
In a room with a very high or sloped ceiling, calculating based on square footage can be misleading. Two spaces with the same floor area can contain very different air volumes.
To properly size a Hitachi wall-mounted heat pump, we consider, among other factors:
- the average and maximum ceiling height;
- the total volume to be conditioned;
- the presence of an open staircase;
- connections to other floors;
- roof insulation;
- window area;
- solar orientation;
- wind exposure;
- the number of occupants;
- heat-producing appliances;
- the desired temperature in winter.
A space with a cathedral ceiling can accumulate a great deal of heat in summer, particularly when the roof is exposed to the sun. In winter, stratification can create a significant difference between the temperature near the ceiling and the temperature felt at floor level.
An undersized unit may run continuously without reaching the setpoint. An oversized unit may produce excessively short cycles, reduce dehumidification quality, and cause temperature fluctuations.
The choice should therefore be based on a thermal load analysis rather than on an approximate rule such as a fixed number of BTUs per square foot.
Comfort, maintenance, and performance: the details that matter after commissioning
Directing air properly in a large space
The high positioning of the unit requires appropriate louver adjustment.
In cooling mode, cooled air is denser and naturally descends. A projection that is slightly horizontal or angled downward generally allows the volume to be covered effectively.
In heating mode, the setting should be directed more noticeably downward. Without this orientation, warm air may remain in the upper area near the sloped ceiling.
The fan speed also plays a role. A speed that is too low can limit the reach of the airflow, while a higher speed helps mix the air in an open room. The automatic mode can be useful, but some buildings benefit from a customized setting depending on the season.
In several projects completed by AirGreen in Montreal, Laval, Longueuil, on the North Shore and the South Shore, we have found that comfort depends as much on the unit’s location and settings as on its rated capacity.
Smart Eco and SleepSense
The Hitachi airHome 800 is equipped with smart features designed to better adapt its operation to the occupants’ habits.
The Smart Eco mode uses a motion sensor to detect when the space is unoccupied. After a period without activity, the system can reduce its operation to avoid unnecessary energy consumption, then resume its settings when occupants return.
The SleepSense function adjusts the temperature at night to limit fluctuations and improve sleeping comfort.
These features are useful in an open space, but their effectiveness depends on the unit’s position and the sensor’s detection range. A very high installation must be planned so that the sensor is not aimed at an area where actual movement would be difficult to detect.
airCloud Go and remote control
The airHome 800 series includes a Wi-Fi interface concealed inside the indoor unit for use with the airCloud Go app.
The owner can, among other things:
- adjust the temperature;
- change the operating mode;
- set a weekly schedule;
- manage certain energy-saving functions;
- view an estimated energy consumption;
- receive certain diagnostic information;
- activate compatible maintenance functions.
For a unit installed very high up, app control becomes particularly convenient. It reduces the need to use the appliance’s physical buttons and allows the system to be managed without standing directly in front of the unit.
FrostWash 3.0 and Mold Guard 2.0
Internal maintenance of a wall-mounted heat pump is important, especially when it is installed at a height where manual cleaning is more difficult.
The FrostWash 3.0 function uses a sequence of heating, freezing, and thawing to trap and then remove some of the contaminants present on the heat exchanger.
The Mold Guard 2.0 system monitors the unit’s internal conditions, even when it is turned off. When the sensors detect an environment conducive to mold growth, the coil is heated to dry the interior.
The unit also includes a PM2.5 activated carbon filter and a stainless steel prefilter.
These features help keep the unit cleaner, but they do not completely replace professional HVAC maintenance. The filters must still be removed and cleaned periodically, and the other components must be inspected according to how the unit is used.
Plan for maintenance access during installation
A heat pump installed very high up remains a mechanical device that will eventually need to be cleaned, inspected, or repaired.
Before selecting the location, we therefore consider the possibility of accessing:
- the front panel;
- the filters;
- the condensate pan;
- the fan motor;
- the fan wheel;
- the sensors;
- the connections;
- the drain.
At this Saint-François job site, access requires a ladder suitable for the wall height. It was therefore important to keep a sufficiently clear area beneath the unit to allow for future service.
Placing a heat pump above a fixed staircase, a piece of furniture that cannot be moved, or a fragile structure can make maintenance complex and costly. Aesthetics should never overshadow the installation’s entire service life.
Mistakes to avoid when installing at height
This installation highlights several common mistakes.
Installing the unit too close to the ceiling
The upper air intake must not be compressed between the casing and the ceiling. A restriction can increase noise and reduce airflow.
Neglecting stratification
In a large space, heat can accumulate at the ceiling. The ventilation speed and louver orientation must be adjusted accordingly.
Using inadequate fasteners
The mounting plate must be securely anchored to a structure capable of supporting the unit over the long term. The unit’s weight, vibrations, and service work must be taken into consideration.
Forgetting about future access
An installation may look neat on the day of the project while becoming almost impossible to maintain later. The location of a ladder or platform must be planned.
Improvising the drainage
The drain must maintain a consistent slope. It must not be compressed, raised, or connected in a way that causes water to back up.
Choosing the capacity based on a rough estimate
Ceiling height and connections with the other rooms affect the heating and cooling load. The total volume must be taken into account.
Checks performed before completing the work
Once the mechanical and electrical installation is complete, we carry out a series of checks.
Our technicians check, among other things:
- the stability of the indoor unit;
- its level;
- the full opening of the louvers;
- airflow;
- the absence of vibration;
- condensate drainage;
- the supply air temperature;
- communication with the outdoor unit;
- heating operation;
- cooling operation;
- the remote controls;
- the integrity of the refrigerant connections.
In a high-mounted installation, drain control is particularly important. A small leak may remain unnoticed for some time before staining the wall or damaging an interior finish.
Eligibility for Heat Pump Subsidies
Certain combinations in the Hitachi airHome 800 lineup may be eligible for financial assistance for heat pumps in Quebec.
Eligibility depends on several factors:
- the exact numbers of the indoor and outdoor units;
- the selected capacity;
- the applicable AHRI or ENERGY STAR reference;
- the residence;
- the program in effect;
- the purchase and installation date;
- the documents provided.
The name “airHome 800” is therefore not enough to confirm an amount. The exact combination must be verified before providing a subsidy estimate.
We recommend keeping:
- the detailed invoice;
- the serial numbers;
- proof of payment;
- the installation date;
- the technical data sheets;
- the required photographs;
- the contractor's contact information;
- the RBQ licence number.
A discreet installation despite demanding architecture
The result achieved in Saint-François shows that a wall-mounted heat pump can be integrated into a space with a sloped ceiling without appearing disproportionate.
The unit was positioned:
- in the upper part of the wall;
- under a ceiling area providing the necessary clearance;
- away from traffic areas;
- at a height that promotes air distribution;
- in an accessible location with the appropriate equipment;
- while taking future maintenance into account.
This installation involves more than simply choosing a high-performance unit. It relies on a combination of sizing, building analysis, work-at-height safety, drainage, airflow and commissioning.
At AirGreen, we carry out HVAC installations in Saint-François and throughout Laval, as well as in Montreal, Longueuil, the North Shore and the South Shore. Each location is assessed according to its actual constraints so that the heat pump operates properly in summer, winter and the shoulder seasons.