Four-season comfort and installation on a flat roof: a careful achievement by AirGreen
The context and the objective
In a plex in Villeray–Saint-Michel–Parc-Extension , occupants are looking for efficient cooling in the summer and quiet heating in the spring/fall, without cluttering the interior space. We recommend a Gree wall-mounted heat pump from the R-32 range (recent generation), calibrated for the main open area, with the condenser installed on a flat roof to free up the courtyard and optimize noise discretion.
Why Gree (R-32) for this project
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High seasonal efficiencies and R-32 refrigerant , better classified environmentally than older generations (R-410A).
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Reliable behavior at low temperatures , adapted to the climate of Greater Montreal .
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Quiet indoor and outdoor units, ideal for dense plexes.
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Simple HVAC maintenance : washable filters and direct access to maintenance components.
Sizing and capacity selection
After calculating the load (envelope, orientation, internal inputs), a range of 9,000 to 12,000 BTU/h covers the open living room-kitchen area. This choice avoids short cycles , limits consumption and guarantees uniform mixing in the living area.
Our flat roof method: durable and compliant
Indoor installation: optimal diffusion and easy maintenance
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Install high on the wall , ~ 15–20 cm from the ceiling to maximize suction and sweeping.
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Side clearances respected for accessibility during HVAC maintenance .
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Through-hole with outward slope for gravity drainage ; sealed bulkhead to block air and moisture.
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Communication power supply and connections positioned for visual integration above the furniture, without air recirculation.
Refrigeration connections and cabling: short and protected route
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1/4–3/8" insulated copper (typical configuration 9–12 kBTU).
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Estimated total length: 5 to 8 m , including the climb to the roof.
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White UV capping and stainless steel fixings for the exterior portion, to ensure durability and clean finishes .
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Leak test and high vacuum before opening the valves: system stability and compressor longevity.
Rooftop condenser: stability, drainage and preserved membrane
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High support on rails placed on anti-vibration pads , distributing the loads and protecting the membrane .
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Sufficient clearance under the unit for snow and water drainage; standard clearances around the grilles.
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Anchoring and bracing adapted to urban roof wind loads; precise leveling to avoid vibrations.
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Route of the connections raised and strapped to eliminate any bulging on the ground and facilitate inspections.
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Management of penetrations (flashing/waterproofing) carried out in coordination with the building rules to maintain the roof warranty.
Electricity and commissioning
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Dedicated circuit with circuit breaker suitable for the unit's nominal current; proximity disconnect switch at the condenser for safety.
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Voltage check, absorption control, grounding .
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Extended hot/cold tests : measurement of supply/return temperature differences, noise control, observation of cycles and drain under load.
Measurable result
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Rapid increase in comfort and stability of the setpoint.
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Noise controlled inside and on the roof.
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Short route = minimal losses, high efficiency and optimized energy bill .
Technical details of this achievement
Highlights
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Type : wall-mounted heat pump (mini-split, one head).
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Brand : Gree – recent R-32 range .
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Capacity : 9–12 kBTU/h for the open area of the dwelling.
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Route : ~ 5–8 m insulated copper connections, UV capping , rise to the roof.
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Condensate drain : gravity , slope controlled when drilling.
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Roof support : rails on skids, silent blocks , snow clearances and maintenance.
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Commissioning : high vacuum , leak test , electrical checks, user training.
Recommended HVAC maintenance
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Filters : clean every 2–3 months (more frequently if there are animals/dust).
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Annual inspection : pressure/probes, fan, condensate tray, tightening connections, defrosting test and checking roof fixings.
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Winter : keep the area around the condenser clear of ice/snow, keep the grilles free for good air flow.
Good usage practices
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Realistic setpoint (22–23°C) and AUTO mode to optimize cycles.
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Vertical/horizontal sweep activated to homogenize the temperature.
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Avoid obstructing the indoor unit (curtains, high shelves) to maximize exchange .
Pitfalls to avoid when installing on flat roofs
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Direct support on the membrane without pads: risk of fingerprints, wear and noise.
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Insufficient height under the unit: accumulation of snow/water, accelerated corrosion.
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Leaky penetrations : infiltration and thermal losses.
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Oversizing : short cycles, discomfort and overconsumption.
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Unprotected UV wiring : premature aging and costly interventions.
Deadlines, coordination and subsidies
A project of this type is generally completed in one day : protection of surfaces, drilling, installation of connections, installation on the roof, testing and commissioning .
High-efficiency R-32 wall-mounted heat pumps are generally eligible for grant programs based on specific criteria and time periods. We assist our clients in preparing their application , verifying eligibility , and maximizing financial assistance.
AirGreen: local HVAC expertise
We operate in Montreal , Laval , Longueuil , on the North Shore and the South Shore . Our teams understand the realities of plexes (exterior stairs, white roofs, technical access) and deliver clean, durable and efficient installations – whether it is a first installation or a modernized replacement to the new R-32 generations.
Naturally integrated keywords : heat pump , wall-mounted heat pump , wall-mounted air conditioner , HVAC installation , HVAC maintenance , Montreal , Laval , Longueuil , North Shore , South Shore , Villeray–Saint-Michel–Parc-Extension , Gree , R-32 , flat roof .