Installation of a GREE (R-32 range) wall-mounted heat pump in Mercier–Hochelaga-Maisonneuve
Hochelaga-Maisonneuve Project: GREE R-32 wall-mounted heat pump installed on a flat roof with anti-vibration rails, watertight disconnect switch, and complete commissioning protocol. AirGreen — HVAC installation experts in Montreal and surrounding areas.
Take a tour of the installation
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.
The context: flat-roofed building, technical access and requirement for silence
In a building in Mercier–Hochelaga-Maisonneuve, our client wanted a compact HVAC solution to air condition living areas on the top floor, with reliable heating backup during the off-season. The choice of a GREE (R-32) wall-mounted heat pump was obvious: a discreet indoor unit for daily comfort and an outdoor condenser neatly installed on the flat gravel roof , away from air intakes and obstacles.
Why GREE in R-32 for this project
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Efficient inverter compressor and fine modulation at low load.
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R-32 refrigerant: better heat transfer, lower charge at equivalent capacity.
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Good capacity maintenance in negative temperatures usual in Montreal .
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Wide range 9k–24k BTU suitable for condos and plexes; precise selection after load calculation (surface area, windows, orientation, infiltration).
Rooftop installation: stability, waterproofing and durability
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Rail supports with anti-vibration blocks: load distribution without puncturing the coating.
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Clearances respected around the exchanger for optimal air sweeping and efficient defrosting in winter.
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Waterproof technical path (roof passage) for refrigeration lines and power supply, with vapor barrier recovery and membrane-compatible sealing.
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Outdoor disconnect switch box in a weatherproof enclosure, within easy reach for maintenance and compliant with local electrical requirements.
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Protected line routing in a UV trunking to the interior descent; the bend radii are respected to preserve the flares and avoid any stress on the fittings.
AirGreen commissioning: documented protocol
We apply a rigorous protocol, identical to our sites in Montreal , Laval , Longueuil , North Shore and South Shore :
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Nitrogen leak test (controlled high pressure) with zero loss recording.
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Deep vacuum draw down to < 500 microns then stabilization (ascent test).
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Opening the valves and weighing/adjusting the charge if the refrigeration length deviates from the factory charge.
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Start-up and measurement log : pressures, intensity, inlet/outlet temperatures, ∆T at the blower outlet, defrost mode control.
Condensate path: reliability first
Drainage is designed using gravity when the geometry allows (continuous slope from the interior head to the discharge point). When the architecture requires a rise, we add a silent condensate pump with a safety tank and alarm. The goal: zero overflow, even during intense dehumidification .
Noise and vibrations: neighborhood preserved
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Anti-vibration pads on the rails and controlled hose tension to prevent any structural transmission.
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Fan orientation and distance from neighboring equipment to reduce air recirculation and noise felt on the terrace.
Capacity selection and comfort achieved
On this type of housing, the target power is generally between 12,000 and 18,000 BTU depending on the load calculation . Result obtained after adjustments:
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Even cooling of living spaces, without “cold snaps”.
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Efficient heating support in spring/autumn, with modulation to avoid short cycles.
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Controlled consumption thanks to the high seasonal efficiency of GREE models in R-32 .
What we particularly look out for on a flat roof
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Walking paths and winter maintenance: clearing snow around the condenser to preserve the air intake.
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Water management : positioning outside runoff path, anti-tilt wedges.
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UV protection for insulation and cables; stainless steel clamps and tape adapted to the climate.
Electricity and compliance
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Dedicated circuit from the panel with suitable circuit breaker, cold climate rated outdoor cable, and proximity disconnect switch .
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Check polarity/ground and tighten to the correct torque on terminal blocks.
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Documentation provided to the customer: single-line diagram, nameplates, serial number, commissioning records.
HVAC maintenance: maintaining performance
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Inner head filters : Clean every 4–6 weeks during use.
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Annual inspection by AirGreen: pressures, intensity, ventilation, drain control, coil cleaning and parameter updates.
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On the roof: check the fixings , condition of the membrane around the roof passage and clear any obstacles.
Pitfalls to avoid (feedback)
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Leaky air barrier opening : condensation and odors — we systematically restore the seal.
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Excessive refrigeration lengths without charge recalibration: declining efficiency — we adjust the charge and validate superheat/subcooling .
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Air recirculation in a hidden facade: capacity losses - hence our studied clearances and orientations.
What the customer gains in Hochelaga-Maisonneuve
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Four-season comfort with a recent R-32 heat pump .
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Discreet rooftop installation that frees up the facades and respects the aesthetics of the building.
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Measured and archived commissioning for seamless monitoring.
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Easy access for HVAC maintenance , ensuring longevity and low operating costs.
What about subsidies?
Depending on the chosen configuration and the presence of efficiency certifications (e.g., ENERGY STAR for extreme cold for certain power levels), this type of installation may be eligible for assistance in effect in Quebec. We validate eligibility and, where applicable, include the required certifications in the file.
Areas served : Montreal , Laval , Longueuil , North Shore , South Shore .
Need technical advice for a flat roof or condominium ? Our team sizes, installs, and maintains your GREE wall-mounted heat pump with a documented and transparent approach.
The big day, step by step
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 would it look like 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.
Four mistakes we do not make
Flip each card to see what we do instead.
Your own project, step by step
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.
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.
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).