Two exterior units perfectly integrated on a Montreal roof: four-season performance, controlled noise and neat aesthetics
At AirGreen , we have just completed an iconic HVAC installation in Montreal's housing stock: two Sharp R-32 condensers from the ZU1 series , dedicated to wall-mounted heat pumps serving stacked housing in Villeray–Saint-Michel–Parc-Extension . The work is taking place on a flat gravel roof , with a parapet and typical roofing equipment (chimney, vents). Our mandate: to provide stable comfort in summer and winter , reduce noise from the facade , and preserve the integrity of the envelope thanks to a thoughtful, sustainable and safe refrigeration and electrical connection route.
Why a flat roof installation in Villeray–Saint-Michel–Parc-Extension
The area is composed of high-density plexes and small residential buildings. Backyards are narrow, street frontages are close to sidewalks, and mature vegetation amplifies sound reverberation. By placing the condensers on the roof , we:
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move noise sources away from bedrooms and immediate neighbors;
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free up floor space in the backyard;
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let's optimize the air draft of the units, away from obstacles;
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make maintenance easier without going through common areas.
This choice also improves durability : far from the projections of snow compacted by snow removal from alleys and protected from accidental knocks, the devices maintain their performance over the seasons.
Configuration chosen: two Sharp R-32 condensers, dedicated to wall heads
We selected the Sharp ZU1 (R-32) range for its balance of efficiency and reliability in cold climates and its compatibility with modern, low-noise wall-mounted units . Each condenser powers a wall-mounted indoor unit installed on the corresponding floor. This dual-system approach offers:
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Redundancy : If one unit requires more heating/air conditioning, the other is not impacted.
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Measurability : independent electrical circuits and guarantees.
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Simplicity of service : targeted diagnostics and parts, minimized downtime.
Usual capacities : 12,000 to 18,000 BTU per dwelling for main rooms (living room + open area), adjusted after thermal load calculations (orientation, insulation, infiltration, windows).
Mechanical installation: stability, clearances and drainage
Our technicians install the condensers on raised aluminum bases attached to rails resting on protected gravel. Anti-vibration rubber pads cut off the transmission to the structure. Standard clearances are respected on all sides to ensure optimal airflow.
Points of attention:
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Increased clearance height to anticipate winter snow accumulation and promote water flow during heavy rain.
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Laser levels to align the two units and maintain a perfectly horizontal housing , essential for defrost cycles.
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Orientation chosen to limit the backflow of hot air in summer and direct exposure to prevailing winds in winter.
Refrigeration and power supply connections: a clean, sustainable and watertight route
The refrigeration connections (high-density insulated copper) are sheathed and UV-protected . On the roof, they follow a grouped route in a resistant black sheath, raised by supports to avoid water pockets. The passage to the parapet is via:
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a waterproof crossing (roof compatible mastic + collars),
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a restored vapor barrier ,
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and a continuous cover up to the interior risers.
Power is supplied from dedicated circuit breakers in each dwelling, with accessible disconnect boxes and clear identification. Grounding follows the requirements of the Quebec Electrical Code.
Condensate management and winter protection
For wall-mounted heads , the evacuation is gravity-fed to the outside, avoiding the use of a pump (reduced noise and maintenance). On the condenser side, we integrate:
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crankcase resistors when required by the data sheet,
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optimized defrosting thanks to the series inverter logic,
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and customer recommendations on snow clearance around appliances after storms.
Upon request, we add modular snow guards or windscreens when roof exposure requires it.
Commissioning: AirGreen precision and quality control
The performance of a heat pump depends as much on the installation as on the choice of model. Our protocol includes:
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Controlled flaring and brazing , active nitrogen purge.
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Nitrogen leak test , then high vacuum (< 500 microns) with stabilization.
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Check lengths vs. load charts; adjust if required.
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Check the currents and voltages , tighten the terminals to the recommended torque.
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Mode settings (winter priority heating, automatic restart after breakdown).
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Final measurements : delta T, static pressure available in indoor blowing, sound levels.
Each unit receives a user guide and our HVAC maintenance tips : filter cleaning, clearance around condensers, and recommended annual inspection .
Energy efficiency and program eligibility
The Sharp ZU1 range in R-32 refrigerant has a high coefficient of performance in mid-season and heating capacities in extreme cold adapted to Greater Montreal. Depending on the sizing and the ENERGY STAR certification , the project may be eligible for subsidies available in Quebec. We support our clients for:
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check eligibility by power and low temperature performance ;
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gather installation documents (serial numbers, detailed invoices);
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submit applications on time.
Results: acoustic comfort, controlled consumption, preserved facade
Rooftop installation drastically reduces noise perception on the facade and in the courtyard. The homes gain in thermal comfort : rapid cooling during heat waves, stable heating in winter, dehumidification during humid periods. The owners note:
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reduced operating costs compared to electric convectors;
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real estate valuation thanks to a recent, clean and discreet system;
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the absence of visible devices in the courtyard, preserving the aesthetics of the building.
AirGreen Best Practices for Montreal Flat Roofs
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Always raise the condensers (rails + pads) for drainage and snow.
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Protect refrigeration insulation against UV rays and abrasions .
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Avoid puddles : walkways on supports rather than in contact with gravel.
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Seal all penetrations with roof-compatible products and manufacturer's guarantees .
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Plan access for maintenance (walkways, clearances, anchor points).
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Inform occupants : clean filters = efficiency and silence .
Why choose us?
We cover Montreal, Laval, Longueuil, the North Shore and the South Shore . Our team is familiar with the constraints of plexes , low-slope roofs , long walkways and coordination with roofers and electricians. Our promise: a HVAC installation that lasts over time, is documented , safe and optimized for the local climate.
In short
Two Sharp wall-mounted heat pumps powered by R-32 condensers neatly installed on a flat roof in Villeray–Saint-Michel–Parc-Extension: a quiet , economical , and architecturally sound solution. At AirGreen, we transform urban constraints into tangible benefits for occupant comfort, all year round.