An HVAC installation designed for Montreal winters, on a flat roof, with snow clearance and easy maintenance
At AirGreen , we have just installed a Midea28 wall-mounted heat pump ( R-454B refrigerant, extreme cold performance) on the flat roof of a residential building in the southwest of Montreal . The objective: to offer four-season comfort to a housing unit converted into an open space, while respecting the constraints of a white roof exposed to wind and snow accumulations. This achievement illustrates our know-how in rooftop HVAC installation , a demanding context where every technical detail counts for reliability and durability .
Client context and needs
The owners wanted to replace a seasonal air conditioner with an energy-efficient solution capable of providing both heating and cooling . The constraints identified during the technical visit:
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Accessible flat roof , with recent elastomeric membrane to protect.
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Exposure to wind and snow drifts requiring unit elevation .
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Need for short refrigeration path to the housing to maximize efficiency.
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Explicit demand for quiet operation and simplified maintenance .
Why the Midea28 for Greater Montreal
The Midea28 is perfect for Montreal winters:
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R-454B refrigerant : new generation, more efficient than older blends, and aligned with regulatory developments.
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Capacity suitable for medium to large housing (9k to 33k BTU depending on configuration), with stability down to −30°C , a crucial point for the North Shore , the South Shore , Laval and Montreal .
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Inverter technology for fine modulation, reducing on/off cycles and consumption.
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Low noise level, ideal for buildings where the peace and quiet of neighbors and occupants is a priority.
Rooftop design and installation: the AirGreen approach
Roof installations require detailed engineering . We have chosen to install them on a raised aluminum frame , placed on pads and distribution soles in order to protect the membrane and distribute the loads :
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Raised by approximately 450–600 mm to ensure snow clearance and facilitate frost runoff during defrost cycles.
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Anti-vibration pads under the chassis to limit the transmission of vibrations to the structure.
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Disconnect box (service disconnect) in the immediate vicinity, installed at a safe height, with sheathed wiring and sealing at the bushings.
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Optimized refrigeration path (≈ 5–8 m visible on this configuration) with high-density insulated pipes, stainless steel collars and controlled bend radius to preserve the fluid charge.
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Waterproof roof passage : membrane-compatible flashing and sealant, for clean passage of refrigeration lines and communication cables to the accommodation.
Condensate management in winter: a key point
On a flat roof, controlling condensate determines the longevity of the system:
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In heating mode, the Midea28 performs defrost cycles . The water from the frost is directed towards a free flow away from traffic areas, in order to avoid refreezing under the appliance.
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Controlled slope of bearing surfaces and clearance under the unit to prevent the formation of ice stalagmites .
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If required by the site, we plan for heating tracing of critical sections or a collection tray drained to a drain; here, the topography of the roof allowed for simple and reliable gravity drainage .
Safety, endurance and maintenance
Working on roofs requires high standards:
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Stainless steel fixings and anti-corrosion treatments to resist salts and frost.
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Controlled tightening torques , deep vacuum and documented leak test before final loading.
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Clear service path around the unit (clearances in accordance with manufacturer recommendations) to facilitate annual HVAC maintenance : cleaning the exchanger, checking pressures, checking the fan and sensors.
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Clear circuit identification on the panel and device labeling to speed up future interventions.
Interior integration: comfortable diffusion and silence
Inside, the Midea28 wall-mounted head was placed at the top of a load-bearing wall, in the heart of the open area. This positioning:
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Breaks stratification in winter thanks to efficient cross-sweeping.
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Limits the direct impact on rest areas (sofa, reading corner).
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Allows a short and discreet refrigerated path , covered from the roof outlet to the vertical passage, for a neat finish.
Performances and results obtained
Upon commissioning, occupants noted:
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Fast heating in very cold weather, without excessive noise during power ramps.
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Stable setpoint in mid-season, with very little oscillation thanks to the inverter compressor .
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A reduction in electricity consumption compared to the old air conditioner + auxiliary heater combination.
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In summer, effective dehumidification which significantly improves the feeling of comfort, even at moderate settings.
Grants and Compliance
The Midea28 is part of recent programs promoting efficient heat pumps . Depending on the capacity and seasonal efficiency index, customers may be eligible for financial assistance. We support our customers in preparing files and verifying correspondence with active programs in Montreal , Laval , Longueuil , on the North Shore and the South Shore . All our installations follow RBQ and CSA standards , with a commissioning certificate provided to the customer.
Good operating practices (winter/summer)
To prolong performance:
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Clean the internal filters every 4–8 weeks.
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Maintain minimum clearance around the outdoor unit; during storms, remove snowdrifts if necessary.
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Stable instructions for operating the inverter (avoid sudden day/night differences).
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Annual maintenance : electrical check, pressures, probes, fans, condition of the insulating foam and exterior capping.
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In summer, natural shade is desirable but without obstructing the airflow.
What makes the AirGreen difference
Our team, specialized in HVAC installation on flat roofs, operates daily in Greater Montreal . We provide:
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Precise installation engineering : clearance calculations, choice of support, membrane protection and load distribution .
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A quality of finish that can be seen... and felt: silence , aesthetics, easy maintenance.
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Complete support : selection of capacity (BTU), verification of eligibility for subsidies , usage advice, responsive after-sales service .
Technical checklist - highlights of this achievement
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Midea28 wall-mounted heat pump (R-454B) for raised mounting on a flat roof.
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Short, insulated refrigeration path , passages sealed with membrane.
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Proximal disconnection box , standardized and marked wiring.
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Frost management by under-chassis clearance and gravity flow.
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Anti-vibration and stainless steel screws for durability.
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Instrumented commissioning : deep vacuum, vacuum resistance, pressure/temperature measurements, functional heating test.
In summary , the Midea28 installed in Le Sud-Ouest offers a robust and elegant response to the challenges of Montreal flat roofs: high performance , silence , reliability in extreme cold and simplified maintenance . For a similar project in Montreal , Laval , Longueuil , on the North Shore or the South Shore , AirGreen designs and builds custom-made , durable installations ready for the winters here.