Installation of a wall-mounted Gree heat pump on a flat roof in Rosemont–La Petite-Patrie
Installation of a wall-mounted Gree heat pump on a flat roof in Rosemont by AirGreen, HVAC experts in Montreal, Laval, Longueuil, North Shore and South Shore.
In summer, the outdoor unit rejects the house's heat outside.
Generic illustration of this type of installation, not a survey of this job site. Tap a number.
Mounted level on a wall plate, high enough for the air to reach the whole room, with enough space around it to slide the filters out easily.
The refrigerant lines, the communication cable and the drain go through the wall in a single opening, sealed against water, cold air and insects.
Two insulated copper pipes connect the two units. Outside, a line cover can protect them from sun, knocks and weather.
A shut-off switch near the outdoor unit isolates it safely for service. It must stay accessible at all times.
The compressor and the fan. In heating mode it captures heat from the outdoor air, even in winter, and moves it inside.
On the ground or on the wall, it keeps the unit above accumulated snow. The unit stays clear and defrost water can drain away.
The fan needs to blow freely. Storage, a fence or a wall too close, and efficiency drops while noise goes up.
A HVAC project adapted to Montreal's urban environment
At AirGreen , we regularly install wall-mounted heat pumps on commercial and residential buildings in Greater Montreal. This project took place in Rosemont–La Petite-Patrie , an area where urban architecture often poses unique challenges, particularly with flat roofs and high building density. Our team was tasked with installing a Gree wall-mounted heat pump designed to ensure comfort and energy performance, while respecting the building's structural and aesthetic constraints.
Installation context
The building in question is a flat-roofed building housing several rental spaces. The owners wanted an energy-efficient heating and cooling solution capable of operating efficiently even in Montreal's bitterly cold winters. They chose a wall-mounted Gree heat pump , renowned for its reliability, high efficiency, and eligibility for energy subsidy programs in Quebec.
Technical details and configuration
Choice of equipment
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Brand: Gree
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Type: Wall-mounted heat pump (mini-split)
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Power: adapted to the rental space served (12,000 to 18,000 BTU depending on the thermal load)
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Performance: Energy Star certified and efficient operation down to -25°C
Flat roof installation
The installation was carried out on the flat roof of the building, with a specific set-up:
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Raised metal support fixed on rubber soles to avoid direct contact with the roof membrane and ensure stability.
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Refrigeration pipes pass through a sealed technical chimney to ensure watertightness.
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Condensate management by gravity drainage, facilitated by the slope of the roof.
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Respect ventilation clearances to optimize condenser performance and extend its lifespan.
Constraint and solution
One of the major constraints was the presence of several existing roof lanterns and ventilation ducts . To avoid any risk of interference, our team carefully selected the location of the outdoor unit, ensuring future access for maintenance and free air circulation.
The advantages of this installation
For the owner
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Substantial energy savings thanks to Gree inverter technology.
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Four-season comfort : efficient air conditioning in summer, efficient heating in winter.
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Reliability : heat pump designed to withstand Quebec winter conditions.
For the building
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Discreet integration on the roof, avoiding cluttering visible facades.
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Easy accessibility for maintenance without disturbing occupants.
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Real estate valuation thanks to a modern and certified HVAC system.
Grants and incentives available
Building owners located in Montreal, Laval, Longueuil, the North Shore, and the South Shore can benefit from programs such as LogisVert or Hydro-Québec incentives for the installation of high-performance heat pumps. The Gree wall-mounted heat pump used in this project meets the required energy efficiency criteria, thus maximizing the return on investment.
Final result
This Gree wall-mounted heat pump installation in Rosemont perfectly illustrates our team's ability to adapt our interventions to urban realities. By combining technical expertise , respect for architectural constraints and energy optimization , we offered this client a sustainable and efficient solution.
At AirGreen, we are committed to providing turnkey HVAC installations that ensure comfort and peace of mind, whether for residential, commercial or mixed-use buildings, throughout Greater Montreal.
How it goes, from the first call to the end
The main steps of this kind of job at AirGreen. Every house has its quirks: the estimate brings them out.
We look at the room, the outside wall, the line route and where the outdoor unit will go. That is where the capacity gets chosen.
Model, capacity and price, in writing. We also check whether the model qualifies for assistance programs.
Floors and furniture protected, wall plate position marked level, wall opening located.
A single opening, with the slope the drain needs to flow outside.
Set on a stand raised above the snow, with the clearances the manufacturer requires.
Connected, insulated and protected. The opening is then sealed against water, cold air and insects.
A dedicated circuit and an accessible disconnect near the outdoor unit.
Leak test, vacuum, then start-up and a check of heating and cooling.
Remote, modes, filters: we show you the essentials before we leave.
- The on-site estimateWe look at the room, the outside wall, the line route and where the outdoor unit will go. That is where the capacity gets chosen.
- The quoteModel, capacity and price, in writing. We also check whether the model qualifies for assistance programs.
- Getting readyFloors and furniture protected, wall plate position marked level, wall opening located.
- The wall openingA single opening, with the slope the drain needs to flow outside.
- The outdoor unitSet on a stand raised above the snow, with the clearances the manufacturer requires.
- Lines, cable and drainConnected, insulated and protected. The opening is then sealed against water, cold air and insects.
- The electrical workA dedicated circuit and an accessible disconnect near the outdoor unit.
- Tests and start-upLeak test, vacuum, then start-up and a check of heating and cooling.
- The walkthroughRemote, modes, filters: we show you the essentials before we leave.
And at your place?
Two quick checks with real numbers: what heat costs, and what your current heaters add up to in BTU/h.
Conversion: 1 W = 3.412 BTU/h. An indication, not a load calculation: baseboards and furnaces are often stronger than the real need, and they can stay as backup. AirGreen confirms the capacity on site.
What to do, season by season
Three habits per season for this unit. They take a few minutes and prevent many calls.
- Clean the indoor unit's filters.
- Clear leaves and debris left on the outdoor unit by winter.
- Test cooling before the first hot days.
- Clean the filters more often when the unit runs a lot.
- Keep plants away from the outdoor unit.
- Check that no water drips from the indoor unit.
- Rake the leaves around the outdoor unit.
- Test heating before the first cold days.
- Book periodic maintenance before winter.
- Keep snow away from the stand and the front of the unit.
- Let the unit defrost: it is normal.
- Never hit the ice on the fins; call us if the unit stays iced up.
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What people ask us about this kind of work
Does a wall-mounted heat pump heat in winter?
Wall-mounted or multi-zone: how do I choose?
Where does the outdoor unit go?
Are there grants?
Do I need a permit?
How cold can it heat?
How much can I save?
How is the LogisVert assistance calculated?
Is it noisy?
The outdoor unit is covered in ice: is that normal?
Does AirGreen hold the required licences?
Is the estimate free?
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Text and photo: a real AirGreen Climatisation & Chauffage job. The diagrams are generic illustrations of the type of installation, not a survey of this job site. Sources of the added figures: airgreen.ca product pages (NEEP / AHRI performance), Hydro-Québec (Heat pumps page, LogisVert, read on 13 October 2026), Régie de l’énergie (rate D as of 1 April 2026).