A flat roof mount designed for Montreal winters, stable in powder snow and efficient even in the coldest weather
Urban context and customer needs
In Rosemont–La Petite-Patrie , brick plexes with flat roofs dominate. Our client occupies the top floor of a triplex and wants stable heating and cooling comfort, without disturbing neighbors and without encroaching on the backyard. We offer a Sharp R-32 series wall-mounted heat pump , suitable for Montreal winters and humid summers, with a rooftop mount to free up facades.
Why Sharp R-32 Series for this building
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Low GWP refrigerant (R-32) meeting new requirements.
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High seasonal yields and low temperature capacity maintenance, ideal for four-season use in Montreal , Laval , Longueuil , North Shore and South Shore .
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Low noise level of the condenser, an advantage for dense environments.
Sizing: For a top-floor dwelling, we generally plan for 12,000 to 18,000 BTUs for the main area, to be confirmed by load calculations (insulation, orientation, air infiltration). Here, the thermal analysis points to a unit from the series comfortably covering the living room and the adjoining bedroom.
Construction site challenges and AirGreen solutions
1) Snow-covered flat roof: preserve airflow
On the roof, the snow formed irregular drifts. We installed the condenser on a raised galvanized support (~60 cm rise) to maintain:
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a free air intake above the accumulations;
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a clear discharge away from blown snow;
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a usable service area.
Anti-vibration pads isolate the structure. The foundation is aligned with the rafters to distribute the loads without creating pressure points on the membrane.
2) Bad weather and wind
The roof edge provides a partial windbreak. We position the unit away from the wall to prevent air recirculation and premature icing. The orientation limits the suction of powdery snow. The protected stainless steel anchors ensure wind resistance.
3) Defrosting and water management
In heating mode, defrost cycles discharge water. The bench is designed to drain by gravity to a disposal area without running off into sensitive drains. If necessary, a discreet deflector directs the flow. No external pump is required.
4) Clean and sustainable refrigeration route
The refrigeration path follows a short route: condenser outlet → sealed penetration via a technical riser → controlled descent in a duct towards the interior head. We use:
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insulated copper, continuous closed insulation , UV shielding tape;
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vapor barrier in sensitive areas and sealed joints;
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sober capping (black) for discreet integration on the interior side, without thermal bridge.
Estimated circuit length: short to medium, which reduces pressure losses and improves efficiency.
5) Safe power supply
Connection via a dedicated circuit breaker and safety switch near the condenser. Heating cable is not required on this route; the insulation is continuous and protected. Grounding is verified, the cable clamps are stainless steel.
Inside: targeted comfort and silence
The wall-mounted airhead is installed in the central area, with airflow toward the living spaces. Laser alignment ensures horizontality for noiseless condensate drainage. The automated dampers distribute the air evenly, limiting frequent stratification on the upper floor.
Commissioning and quality controls
Key steps
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Nitrogen test and leak test.
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Deep vacuum draw to the thresholds required to remove moisture.
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Weighing / load adjustment according to actual line length.
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Electrical checks and direction of fan rotation.
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Cold/heat mode settings , shutter limits, eco settings, Wi-Fi if desired.
What we measure
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Suction/discharge temperatures and superheat/subcooling .
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Absorbed intensity vs. nominal curve.
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Delta-T room supply.
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Noise and vibrations (comparative measurement before/after setting the silent blocks).
Result: stable operation, without resonance in the structure, and a consistent Delta-T in heating even in cold weather.
Recommended HVAC maintenance (winter and summer)
Winter in Montreal
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Monitor snow accumulation around the bench: keep 30 cm free for suction.
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Do not break the ice on the fins: use gentle brushing if necessary.
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Keep the drainage slope clear for defrost cycles.
All year round
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Clean the inner head filters every 1 to 3 months.
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Annual inspection: static pressure, condition of the insulation , electrical tightening, cleanliness of the exchanger.
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Adjustments to energy saving parameters (night settings, programming).
Frequent Pitfalls…and How We Avoid Them
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Condenser placed too low : risk of burial; our riser eliminates this point.
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Air recirculation against a parapet : we keep a free template in suction/discharge.
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Non-watertight holes : here, penetrations with waterproof sleeve and membrane-compatible sealant.
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Refrigeration lines exposed to the sun : UV-stable cover and insulation.
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Vibrations transmitted to the gypsum : silent blocks on the roof side and spacers inside.
Comfort, savings and subsidies
A recent R-32 wall-mounted heat pump allows:
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efficient heating during the off-season and much of winter;
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quiet air conditioning in summer;
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lower bills compared to old electric baseboards.
Depending on the capacity chosen and the performance of the series, the equipment is generally eligible for assistance programs for high-efficiency heat pumps in Quebec. We validate eligibility during the submission and provide administrative support for customers in Montreal , Laval , Longueuil , North Shore and South Shore .
Salient technical details of this installation
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Equipment type : Sharp wall-mounted heat pump – R-32 series .
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Mounting : raised galvanized roof support, stainless steel anchors, anti-vibration pads.
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Context : flat roof of a brick triplex, Rosemont–La Petite-Patrie district.
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Route : short refrigeration lines, sealed penetration, continuous insulation.
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Winter : clearances respected for snow and service; defrosting managed by gravity drainage.
What the customer gains
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Uniform temperature in the day/night area.
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Low visual footprint on the facade.
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Simple and plannable maintenance.
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HVAC installation compliant with local best practices, ready for Montreal winters.
Practical advice for your project
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For a flat roof, choose a rise of ≥ 45–60 cm and generous clearances around the condenser.
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Provide a secure winter access path for maintenance.
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Protect roof penetrations with membrane-compatible products.
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Entrust the sizing to a team that understands the thermal realities of Montreal plexes.
At AirGreen, we design every HVAC system to withstand the climate, integrate with local architecture, and deliver measurable comfort year-round.