A flat roof condenser, designed for the Montreal climate: winter stability, silence, clean finishes and easy maintenance.
Context: a Plateau plex with flat roof and rear access
In this typical Plateau-Mont-Royal plex, the owners want to improve the 4-season comfort of the main floor without increasing the visual footprint on the facade. We chose a wall-mounted heat pump with a condenser installed on the flat roof , a very common solution in central Montreal where people want to preserve open alleys and limit ground noise. The objective: to efficiently air-condition the living area in summer, provide efficient heating support in mid-season and reduce overall consumption.
Equipment selection: Sharp, fine modulation and reliability
Sharp's outdoor inverter units are renowned for their control and resistance to cold climates. The wall-mounted indoor unit (installed on the open-plan side) continuously controls the power to maintain a stable temperature and a discreet noise level.
Key advantages for accommodation in the Plateau:
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Modulation : variable speed adapts power to actual needs, avoiding start/stop cycles.
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Acoustic comfort : Low-vibration fan and compressor are suitable for urban density.
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Air quality : internal filtration limits dust and pollen during transition periods.
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Versatility : heating and cooling in one compact system.
Installation on a flat roof: structure, anti-vibration and membrane protection
We install the outdoor unit on a bolted aluminum frame , which is anchored to treated wood foundations resting on the membrane. This approach distributes the load and prevents punching. Anti-vibration pads under the uprights and at the anchor points reduce the transmission of vibrations to the structure.
Key points:
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Compliant clearances on suction and blowing to preserve air flow.
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Useful height above the roof to prevent snow accumulation and facilitate defrosting.
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Orientations studied so that the air section does not recirculate against a low wall.
The passage of the refrigeration connections and the power supply is made through a sealed crossing : sleeve, sealant suitable for the membranes and clean finish at the foot of the brick wall. The disconnect box is placed within easy reach, in accordance with the safety requirements for HVAC maintenance .
Short refrigeration line and minimized losses
From the wall header located under the roof, we prioritize a direct vertical route to the condenser. This configuration limits:
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the length of the connections (reduction of pressure losses and additional refrigerant),
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tight bends that may impact oil and expansion,
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UV exposure thanks to a discreet cover on the outer portion.
The copper tubes are flared and crimped with a torque gauge, then insulated with high-density foam. We perform a deep vacuum until stabilization and test for leaks before commissioning.
Condensate management and points of attention on the interior side
The interior head evacuates condensation by gravity drain when the configuration allows it; if the slope is insufficient, we integrate a silent mini-pump with flow stopper. The layout is designed to remain invisible in the living area and to facilitate annual cleaning (pan, siphon, overflow detector if present).
Electricity: dedicates, protects, standardizes
The circuit is dedicated with a suitable circuit breaker, wired in a UV- and frost-resistant conduit. The roof disconnect is marked and accessible for maintenance. Grounding and polarity are checked before any operational test. We validate the voltage drop under load and the direction of rotation of the fan.
Commissioning: settings adapted to the Montreal climate
We set the machine for the large local thermal gap :
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optimization of the defrosting curve ,
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adjustment of the shutter sweep to mix without creating a draft,
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calibration of the probe to avoid early shutdown due to stratification under the ceiling,
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validation of pressures (superheating/subcooling) and blown temperatures.
Occupants receive our usage recommendations : in summer, setpoint 23–24°C, Auto mode and moderate ventilation; in spring and fall, use for heating to limit the use of electric baseboard heaters. In periods of severe cold, the heat pump remains an effective supplement as long as the operating range allows it.
Tangible result: stable comfort and controlled bill
In a Plateau apartment building, the air quickly heats up in the afternoon. The heat pump maintains a consistent temperature without overcooling the room, and the gradual dehumidification makes evenings more pleasant. In the mid-season, the machine covers a large portion of heating needs, which reduces bills and improves indoor air quality.
Best practices for a flat roof condenser
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Keep 1 m free in front of the blower and clear the snow around the frame.
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Avoid screens that are too close, which cause air recirculation.
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Plan a maintenance visit without clutter (antennas, trays, cables).
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Inspect the membrane at the end of winter and after high winds.
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Schedule annual HVAC maintenance : exchanger cleaning, connection tightening, fan check and electronic settings.
What else we do at AirGreen
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Finishes : clean UV covers, clean seals, stainless steel fixings where exposed.
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Acoustics : sized chassis, suitable pads, blowing orientation.
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Aesthetics : no visible cables; disconnection painted if necessary to blend in with the wall.
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Local service : rapid intervention in Montreal , Laval , Longueuil , North Shore and South Shore , seasonal monitoring and optimization advice.
Frequently asked questions we address in the field
Odor during restarts? An indoor coil drying cycle and regular maintenance limit moisture-related odors.
Roof noise? We combine anti-vibration and orientation to prevent resonance from walls and parapets.
Lifespan? A well-maintained heat pump maintains its performance; preventive maintenance prevents clogging and maintains seasonal efficiency .
Key technical details of this installation
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Sharp condenser ( Eco Inverter range) mounted on an aluminum frame with anti-vibration pads .
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Treated wood soles : load distribution on the membrane .
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Disconnection box accessible on brick wall.
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Watertight feedthrough and UV cover; optimized short refrigeration connections.
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Clear side maintenance access for exchanger cleaning and seasonal inspection.
Grants and Eligibility
Depending on the exact capacity and performance of the system, a portion of the costs may be eligible for certain programs in effect. We help validate the criteria (seasonal efficiency, heating performance in cold weather) and prepare the file for Greater Montreal : Montreal , Laval , Longueuil , North Shore , South Shore .
Recommended maintenance plan
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Annual : complete inspection (tightness, pressures, fans), cleaning of the external exchanger and the internal head, drain check, updating of parameters if necessary.
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Seasonal : rinsing filters, clearing clutter around the condenser, checking covers and fixings after strong winds.
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Use : favor stable settings, avoid excessive night/day differences, and let the machine manage the humidity in summer.
Naturally integrated keywords : heat pump , wall-mounted air conditioner , HVAC installation , HVAC maintenance , Montreal , Laval , Longueuil , North Shore , South Shore .