A flat roof installation designed for the Montreal climate, durability and maintenance access
Project background
In a typical Plateau-Mont-Royal building, we are installing a GREE wall-mounted heat pump (recent R-32 range) to cool and heat the top-floor apartment. The dense urban environment, flat gravel roofs, and high parapets require a rigorous HVAC installation approach to ensure year-round performance, safe cooling paths, and ease of service.
Why a GREE wall-mounted heat pump in an urban environment?
-
Energy efficiency : The new R-32 ranges offer better seasonal performance, an optimized refrigerant charge and stable capacity at low temperatures — a real advantage for Montreal , Laval , Longueuil , North Shore and South Shore .
-
4-season comfort : reliable heating in negative temperatures and silent air conditioning in summer, with inverter modulation limiting electrical peaks and temperature variations.
-
Easy HVAC maintenance : Easy access to the rooftop condenser and internal components are well-arranged for annual checks.
For equivalent performance, we favor the latest generation R-32 units for their better energy density, simplified maintenance and compatibility with GHG reduction requirements.
Installation method: precision, safety and durability
1) Choice of installation on a flat roof
We choose to position the unit set back from the parapet, with clearances in accordance with the manufacturer's recommendations to optimize heat exchange and avoid air recirculation. Circulation around the unit remains clear for maintenance and winter defrosting.
2) Support and protection of the membrane
-
Galvanized roof frame placed on treated wooden pads and shock-absorbing soles to distribute the load on the gravel and protect the membrane.
-
Sufficient height to keep the unit clear of snow accumulation and to allow condensate to drain.
-
Stainless steel fasteners and anti-corrosion treatment of sensitive points: this is crucial with the Plateau's freeze/thaw cycles.
3) Refrigerated and electrical route
-
Short, straight section preferred to minimize pressure losses and facilitate subsequent diagnostics.
-
Protected passage through the parapet or slab with a waterproof sleeve and vapor barrier ; insulated and UV-capped refrigeration connections to preserve the insulation and finish.
-
Dedicated power supply from the home's electrical panel, with calibrated circuit breaker and external disconnector near the condenser for safe work.
4) Commissioning: invisible but decisive quality
-
Flares calibrated with a torque meter, checked with a template to guarantee the tightness of the connections.
-
Nitrogen test and pressure drop test.
-
Triple evacuation with a vacuum pump to the desired level, maintenance under vacuum and control of the rise; this step determines the longevity of the compressor and the absence of humidity in the circuit.
-
Opening of service valves and checking of superheating/subcooling in heating and air conditioning mode, with recording of reference values.
5) Condensate management in air conditioning mode
On roofs, gravity drainage is preferred, with a controlled slope towards a planned drainage point. When the configuration requires it (excessive length or risers), we integrate a silent condensate pump , with a safety tank and pressure switch.
Results obtained
-
Discreet noise level felt in the home thanks to the detached support and the modulation of the external fan.
-
Temperature stability during periods of heatwaves and winter thaws; reduction of air currents through inverter technology.
-
Optimized maintenance access : accessible interior filters, exterior clearances respected, refrigeration route documented for future inspections.
Technical advice for flat roofs in Greater Montreal
Defrosting and snow management
-
Allow for minimum clearance on three sides and raise the bracket so that blown snow does not block the battery.
-
Avoid vortex areas near high walls; if necessary, install a wind deflector.
Link protection
-
UV cappings extend the life of the insulation; they also prevent direct heating in the sun and protect against birds.
-
At each change of direction, use generous elbows to maintain the minimum radius and limit losses.
Electricity and safety
-
A sealed, accessible external disconnect switch is essential for the safety of technicians.
-
In older buildings, we check the grounding and circuit breaker rating; in the case of modernization, we coordinate with a master electrician.
Recommended HVAC maintenance
-
Spring : cleaning the external battery, checking the fan, tightening the terminals, gentle washing with water.
-
Summer : condensate check, inspection of line insulation and capping.
-
Autumn : test in heating mode, check of reference refrigeration parameters.
-
Winter : clear snow around the condenser, check defrosting.
An annual maintenance plan maintains performance, reduces consumption, and extends the lifespan of your equipment. At AirGreen, we document each visit (values, photos, comments) for transparent follow-up.
Grants and Compliance
Recent R-32 wall-mounted heat pumps with good low-temperature performance are generally eligible for assistance programs when the criteria are met (replacement of an energy-intensive system, certified performance, installation by qualified professionals). We guide our clients in Greater Montreal through the process, with estimates of potential amounts based on the housing configuration.
Common mistakes… and how to avoid them
-
Undersized support : we install robust roof frames, with load distribution and cushioning.
-
Refrigeration route too long : optimization of the route and calculation of additional load if necessary.
-
Improvised condensate drainage : controlled slope, non-return components, safety tray.
-
Commissioning dispatched : complete protocol (nitrogen, deep vacuum, measurements), recording of results.
-
Neglected maintenance access : our plans provide clearances and circulation to facilitate future maintenance.
What the client gains from this project
-
All-season comfort with a latest-generation heat pump .
-
Controlled energy bills thanks to inverter modulation and commissioning optimization.
-
Peace of mind : careful installation, compliant with best HVAC practices for flat roofs in Montreal.
Summary technical sheet (Plateau-Mont-Royal project)
-
Type : single-zone wall-mounted heat pump , recent GREE R-32 range.
-
Installation : flat gravel roof, galvanized frame on cushioned pads.
-
Route : insulated and covered refrigeration connections, sealed crossing, external disconnector.
-
Commissioning : nitrogen test, deep vacuum, hot/cold parameter check.
-
Maintenance : annual plan recommended; easy service access.
Do you have a flat roof in Montreal, Laval, Longueuil, North Shore or South Shore?
Our specialized HVAC teams are experts in the complex and condominium challenges: access logistics, membrane protection, acoustics, and route optimization. We offer a detailed technical quote, advice on grants , and a rapid response schedule—without compromising on quality.
To remember
-
GREE R-32 wall-mounted heat pumps are ideal for Montreal flat roofs when installed on a frame , properly cleared and commissioned according to best practice.
-
Particular care in commissioning and protecting connections guarantees long-term performance.
-
Regular HVAC maintenance prevents overconsumption and extends the life of the equipment.
AirGreen supports owners and condominium syndicates for efficient, sustainable HVAC solutions adapted to Greater Montreal .