An HVAC upgrade designed for Montreal's extreme cold
On a typical Rosemont–La Petite-Patrie flat roof, our team is installing a Sharp wall-mounted heat pump (ZU1 range, R-32 refrigerant) to provide a residential plex with reliable heating in winter and efficient air conditioning in summer . The goal: to increase comfort, reduce consumption and secure the installation for winters down to -30°C , while respecting the constraints of a building with a gravel roof.
Client background and objectives
The owner wanted to replace an aging air conditioner with a quiet, four-season solution capable of maintaining stable comfort in the main rooms, with controlled consumption and simplified maintenance . We recommended a recent Sharp ZU1 (R-32) for its Inverter technology , its low-temperature stability, and its compatibility with Quebec energy efficiency requirements.
Key steps to a successful flat roof installation
Site analysis and preparation
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Inspection of the flat gravel roof : slope, runoff areas and permitted anchor points.
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Check clearances around the condenser to ensure optimal airflow .
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Routing plan for refrigerant lines and wiring to indoor heads.
Supports, anti-vibrations and load distribution
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Installation of a galvanized aluminum frame placed on insulating pads (high density foam) and treated beams to distribute the load without puncturing the membrane.
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Controlled tightening of fasteners with rubber washers to absorb vibrations and limit sound transmission to the housings.
Lines, insulation and electricity
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Closed foam insulated refrigerant line routing, UV resistant outer sheath, abrasion shield on contact areas.
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Waterproof disconnect box near the unit and electrical conduits placed on risers, to avoid any direct contact with gravel and water.
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Grounding and calibration of the dedicated circuit breaker , in accordance with the Canadian Electrical Code and RBQ requirements.
Vacuuming, charging and commissioning
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Vacuum draw < 500 microns , nitrogen leak test , then load balancing according to actual lengths.
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Soft start, pressure check , subcooling/superheat, and indoor blow-out temperature control.
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Programming of silent modes and defrost settings adapted to roofs exposed to wind.
Why the Sharp ZU1 (R-32) range is suitable for this project
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Cold climate performance : Inverter compressor and efficient defrost algorithms maintain capacity when temperatures drop.
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R-32 refrigerant : better energy efficiency and reduced carbon footprint compared to R-410A.
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Quiet operation : Optimized fan and compressor design, ideal for dense residential areas.
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Simplified maintenance : easy access to components, washable interior filters, and rapid diagnostics.
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Eligibility for assistance programs (depending on configuration, power and criteria in force), an asset for owners in Montreal, Laval, Longueuil, North Shore and South Shore .
Details visible on the installation (photo)
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Sharp “Eco Inverter” condenser on raised aluminum frame .
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Timbers placed on insulating soles to protect the membrane and stabilize the assembly.
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Grouped wiring and refrigerant lines , black UV sheath and gray disconnect box at regulatory distance.
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Gravel roof clear of any obstacle in the blowing axis for optimal heat exchange.
Challenges encountered… and AirGreen solutions
1) Wind and runoff on flat roofs
We orient the unit to prevent re-blowing and keep cables away from runoff areas. Insulating risers and pads keep components out of the water and limit corrosion.
2) Transmission of vibrations
The insulating pad + chassis duo and the precise fan alignment reduce structure-based noise . The result: a very low sound signature inside.
3) Line length and pressure losses
We optimize the route of the connections (most direct path, conforming curvature radii), to maintain the nominal capacity and reliability of the compressor in the long term.
Best practices for urban landlords
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Condenser clearances : Do not store anything closer than 60–100 cm to avoid disrupting airflow.
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Defrosting in winter : plan for snow clearance and check the defrost water flow.
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HVAC Maintenance : Annual maintenance (cleaning, tightening, electrical measurements, refrigerant check) extends lifespan and maintains seasonal performance .
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UV and weather protection : the sheath of the connections must remain intact; promptly report any abrasion or cracking of the insulation.
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Thermostat/Control : Use eco modes and time slots to maximize savings without sacrificing comfort.
Results obtained after commissioning
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Immediate comfort in the service area, with a stable temperature and controlled dehumidification in summer.
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Lower consumption compared to the old device, thanks to Inverter modulation and better COP in the off-season.
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Low noise level both outside and inside, respecting the neighborhood in a densely built-up area.
What we bring in addition: AirGreen expertise
At AirGreen , we design and build robust and clean HVAC systems , suitable for flat roofs, plexes and condominiums in Greater Montreal . Our commitments:
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RBQ / CCQ / Hydro-Québec compliance and compliance with mechanical clearances .
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Selection of recent equipment (R-32 / R-454B) to anticipate the regulatory transition.
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Turnkey service : thermal study, advice on subsidies , installation, documented commissioning and preventive maintenance .
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Rapid intervention in Montreal, Laval, Longueuil, South Shore and North Shore .
Ready to upgrade your comfort?
Do you manage a plex in Rosemont, Villeray, the Plateau , or the Southwest ? We evaluate your building, compare options (Sharp, Gree, Fujitsu, Midea ), and suggest the most cost-effective solution based on your rooms, insulation, and usage. With AirGreen, your HVAC system is designed to last, winter and summer.