Installation of a Gree (R-32) wall-mounted heat pump in Saint-Laurent
AirGreen installs a Gree R-32 wall-mounted heat pump on a flat roof in Saint-Laurent : anti-vibration mounting, insulated connections, sealed penetrations, and complete commissioning. Careful HVAC installation for four-season comfort and energy savings.
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The article, chapter by chapter
A flat roof installation designed to last, quiet and ready for Montreal winters
Project context and client objectives
In Saint-Laurent, a homeowner wanted to modernize hisheating and air conditioning system to improve year-round comfort, reduce his energy bill, and limit noise impact on the facades. We offer a Gree wall-mounted heat pump with R-32 refrigerant , a relevant choice for its performance in cold climates, its low GWP, and its rapid availability in Greater Montreal .
Why a Gree R-32 wall-mounted heat pump?
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Energy efficiency : Recent Gree R-32 units offer very good SEER/HSPF and stable performance in mid-season and mid-winter.
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4-season comfort : efficient heating in cold weather and gentle air conditioning in summer.
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New generation refrigerant : less environmental impact than R-410A.
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Simplified maintenance : easy access to the interior head filters and condenser components.
Flat roof installation: our technical choices
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Support : condenser placed on roof rails with anti-vibration pads to protect the elastomer membrane and eliminate sound transmission into the building.
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Raising : raised chassis (> 12") to free the unit from runoff water and snow accumulation.
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Clearances : respect the clearances around the device to ensure optimal airflow and safe maintenance.
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Refrigeration connections : continuously insulated piping , UV protected by white sheath; direct routing to the technical column to reduce pressure losses.
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Electrical : Dedicated power supply and external isolation (near the condenser) in accordance with the Code, with wiring protected from UV and punctures.
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Waterproofing : penetrations sealed with membrane-compatible mastic and mechanical flashings to maintain the integrity of the roof.
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Condensate management : gravity drainage inside the evaporator side; no free discharge onto the roof, avoiding icing and risks to the membrane.
Key steps in HVAC installation
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Technical visit : taking measurements, identifying the best route (technical column), validating clearances and the electrical connection point.
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Installation of the support : weighted/anti-vibration rails, checking of slopes and existing drainage.
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Drilling and laying of lines : dehydrated copper, brazing under nitrogen, nitrogen pressure test followed by deep vacuum drawing .
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Connections : refrigeration connections, communication cabling, power supply, grounding .
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Commissioning : control of overheating/subcooling, verification of intensities, calibration of heating/air conditioning modes.
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Customer provided with : operating instructions, HVAC maintenance and maintenance schedule.
Results: comfort, silence and savings
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Noise reduction thanks to the anti-vibration support and the distance from the facades.
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Stable temperatures in the rooms served, even during the rapid variations typical of Montreal.
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Increased energy efficiency compared to an old cooling-only air conditioner.
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Preserved aesthetics : no unity on the facade; clean and discreet paths.
Recommended maintenance (to maximize longevity)
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Clean the inner head filters every 4 to 8 weeks during the season.
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Annual inspection : pressures, fans, condensate trays, electrical tightening, condition of the roof membrane around the crossings.
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Winter Clearance : Keep the unit free of blown snow; never obstruct the suction.
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AirGreen Program : tailored HVAC maintenance contracts (residential and small commercial) to maintain performance and warranty.
Potential Grants and Eligibility
Depending on the capacity (BTU) and the efficiency of the chosen range, a recent R-32 wall-mounted heat pump may be eligible for provincial and municipal assistance. We verify for each address in Greater Montreal (Montreal, Laval , Longueuil , North Shore , South Shore ) and assist in setting up the file (proof of installation, AHRI number, detailed invoices).
Common pitfalls to avoid on flat roofs
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Rigid supports placed directly on the membrane: risks of punching and noise; prefer elastomer pads .
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Unsealed crossings : possible infiltration; use materials and techniques compatible with the membrane.
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Too long journeys and unnecessary loops : load losses and reduced efficiency; aim for a short, straight route .
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Condensate discharges on roofs : icing in winter; favor controlled evacuation.
Why AirGreen for your project in Saint-Laurent (and throughout Greater Montreal)
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Specialists in flat roofs and local urban constraints.
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Selection of proven brands (Gree, Fujitsu, Midea, Sharp, etc.) in R-32 / R-454B .
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Technical transparency : precise sizing (thermal load, line lengths, electrical protections), AHRI documentation, and end-of-site photos.
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Local service : dedicated teams in Montreal , Laval , Longueuil , North Shore and South Shore , with realistic response times.
Are you planning a flat roof installation in Saint-Laurent or elsewhere in Greater Montreal?
Our advisors guide you from choosing the heat pump to applying for grants , with careful execution that complies with industry 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).