Installation of a Gree wall-mounted heat pump on a flat roof in Rosemont–La Petite-Patrie
Installation of a Gree R-32 wall-mounted heat pump in Rosemont–La Petite-Patrie. AirGreen is carrying out a project on a flat roof with raised support, careful insulation, and optimized ductwork.
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A custom HVAC installation project in a Montreal duplex
At AirGreen , we regularly encounter atypical configurations that require in-depth expertise and rigorous planning. This was the case for this Gree wall-mounted heat pump installation in a duplex in the Rosemont–La Petite-Patrie neighborhood of Montreal . The main challenge: a flat roof with limited access and the need to optimize the passage of ducts while ensuring perfect stability of the outdoor unit.
Equipment choice: a Gree R-32 wall-mounted heat pump
The client wanted an energy-efficient solution adapted to Montreal winters . We recommended a Gree wall-mounted heat pump operating on R-32 refrigerant , known for its increased efficiency and compatibility with government subsidies. The chosen range is designed to offer reliable performance even in extreme cold, down to -25°C.
Key features of the installed system
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Brand : Gree
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Type : Wall-mounted heat pump (mini-split)
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Capacity : 18,000 BTU (ideal for medium to large spaces)
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Refrigerant : R-32 (more environmentally friendly than R-410A)
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Eligibility : Hydro-Québec LogisVert and Greener Homes grant programs
Technical details of the installation
The installation was carried out in the evening, requiring site lighting to ensure precise execution. Several technical aspects are worth highlighting:
Support and anchoring
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The outdoor unit was fixed on a raised aluminum support , itself stabilized by treated wooden beams.
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This method avoids any direct contact with the flat roof membrane and ensures better weight distribution.
Piping route
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The refrigerant and electrical connections were carefully insulated and capped , then guided towards the roof slope to prevent any accumulation of water.
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A linear route was chosen to reduce pressure losses and simplify future maintenance.
Condensate management
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Thanks to the roof configuration, the flow is by gravity , thus avoiding the installation of a condensate pump.
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Particular attention has been paid to the slope angle to prevent any risk of freezing in winter.
Challenges encountered and solutions provided
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Limited space : The roof angle and proximity of the skylights required a compact installation. We adjusted the height of the bracket to maintain airflow.
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Climatic conditions : Installation in the cold season required increased control of sealing and insulation to ensure optimal performance all year round.
Results and benefits for the client
The installation of this Gree R-32 heat pump in Rosemont now allows the owner to:
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Reduce your energy consumption compared to conventional electric heating.
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Enjoy stable comfort in summer and winter, with precise temperature control.
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Access grants available in Montreal, Laval, Longueuil, on the North Shore and the South Shore .
AirGreen expertise in Montreal HVAC installations
Every wall-mounted heat pump installation project in Montreal is unique. This duplex demonstrates our ability to adapt our methods to a variety of contexts: flat roofs, limited space, aesthetic or climatic constraints. At AirGreen, we always ensure a safe, durable installation that meets the strictest standards.
The job tools
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.
How the job unfolds
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.
What we check on a job like this one
Each number is a point we check on site. Switch between summer and winter to watch air and heat move.
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.
Is your home ready?
Check what applies at your place. A "no" is not a refusal: it is what we sort out during the estimate.
Good habits, once the unit is in place
Six simple habits that keep the unit going. Your list stays on this device.
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.
The right pages, at the right time
Four statements: true or false?
It all comes down to details you have just seen.
1. In heating mode, the outdoor unit can produce water.
During defrost cycles. That water must drain away without forming ice.
2. You pick the capacity with a simple square-footage rule.
Windows, insulation, orientation and how the room is used all count. Capacity is chosen on site.
3. A multi-zone connects several indoor heads to a single condenser.
One head per room, all on the same condenser. Each room keeps its own temperature.
4. The disconnect can sit behind the patio furniture.
It must stay accessible: it is what shuts the unit off for service.
0 / 4 right answers
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?
No question matches. Write to us: we answer.
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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).