Installation of a Sharp wall-mounted heat pump on a flat roof in Rosemont–La Petite-Patrie (Montreal)

An installation designed for Montreal's extreme cold, snow... and peace of mind
At AirGreen , we design each HVAC installation based on the building, the envelope, and the climate. In Rosemont–La Petite-Patrie, we deployed a Sharp wall-mounted heat pump ( Eco Inverter outdoor unit) on a flat roof , with an optimized cooling path and complete winter protection. The goal: to ensure four-season comfort in the home while preserving the roof and performance in extreme cold .

Building context and client needs

Typical Rosemont building: plex with white roof, elastomeric membrane, access to the roof via hatch. The accommodation in question has:

• An open living area overlooking the rear facade;

• Significant temperature variations in summer and winter;

• A location constraint for the outdoor unit (narrow street, inaccessible courtyard) which favors installation on the roof .

The client is looking for:

• Efficient heating down to −25°C with fine modulation;

• Rapid cooling during heat waves;

• A discreet installation that does not encroach on the courtyard and respects the neighborhood;

• A reliable and easy to maintain system.

Choosing Sharp equipment: efficiency, reliability, silence

The Sharp heat pump with inverter technology is perfectly suited to the Montreal context:

• Continuous modulation of the compressor to stabilize the temperature smoothly;

• Very good seasonal performance in air conditioning and heating;

• Quiet design of the outdoor unit, appreciated in dense environments;

• Interior air filtration and night comfort functions.

We select the capacity based on the load calculation (surface area, insulation, glazing, infiltration). On this project, a nominal power of around 12 to 15 kBTU for the main area allows us to balance comfort and consumption.

Flat roof installation: structure, snow and vibrations

The outdoor unit is installed elevated on an aluminum support fixed to distribution pads (“ski” rails) placed on the membrane. This configuration:

• Protects the membrane (no direct anchoring to the roof);

• Maintains ground clearance to evacuate frost during defrost cycles;

• Dissipates vibrations thanks to anti-vibration pads ;

• Facilitates natural de-icing and limits snow accumulation against the device.

We orient the unit to avoid re-blowing towards obstacles (parapets, stumps, guardrails) and guarantee a free flow of air , essential for performance in winter.

Refrigerated path and sealed penetrations

The refrigeration path (1/4"–3/8" insulated copper) follows a short, protected path :

• UV channel on the roof to protect the connections;

• Waterproof penetration to the membrane (sleeve + flashing + compatible sealant);

• Vertical descent into the technical shaft to the interior wall head .

We stay within the manufacturer's recommended length range (≈ 7 to 12 m on this project), which avoids any additional refrigerant . The bending radii are respected to protect against flares and operating overheating .

Condensate drain: gravity first, reliability always

In air conditioning, the condensate drain from the indoor unit is routed by gravity to the outside, which:

• Eliminates the risk of condensate pump failure;

• Reduces noise and maintenance;

• Prevents any moisture from flowing back into the insulation.

On flat roofs, we provide a drainage path for water from winter defrosting cycles to avoid stalactites and accumulation under the unit.

Power supply and electrical compliance

• Dedicated circuit from the home's electrical panel, with a properly sized circuit breaker;

• Outdoor disconnect box near the unit, in a weatherproof enclosure;

• Grounding and routing of cables in compliant conduits.

Rigorous commissioning: guaranteed performance

As on all our HVAC installation sites:

1. High pressure nitrogen test to validate the seal;

2. Deep vacuum (< 500 microns) with stabilization ;

3. Checking intensities , blowing temperatures, superheating and subcooling ;

4. Calibration of shutters and speeds to distribute air over the entire open area;

5. Operating advice: stable instructions , open doors, filter maintenance.

Visible details of the installation (photo)

• Raised aluminum support , placed on distribution pads to preserve the membrane;

• Protected chute and refrigeration lines running on the roof;

• Sufficient clearance under the unit for snow and defrosting;

• Ventilation direction clear of obstacles;

• Simplified winter access for maintenance.

HVAC maintenance: maintaining performance over time

We offer annual HVAC maintenance :

• Cleaning and disinfection of the internal exchanger and filters;

• Inspection of gravity drain , gutters and flashings;

• Checking electrical connections and tightening torque;

• Checking exterior insulation (UV, rodents, bad weather);

• Recording of refrigeration parameters to monitor changes season after season.

A maintenance contract maintains component warranty and preserves energy efficiency .

Best practices for flat roofs in Montreal

• Snow clearance : keep 30 to 45 cm free around the unit;

• Secure access path for winter maintenance;

• Roof snow guard if necessary to prevent massive slides;

• Defrost water management (controlled flow, no ice in front of access points);

• Minimum elevation of 12 to 18 inches to prevent burial.

Grants in Quebec and support

High-efficiency heat pumps are generally eligible for assistance programs based on criteria (minimum efficiency, cold operation, envelope availability). We support our customers in Montreal, Laval, Longueuil, the North Shore and the South Shore to verify eligibility, gather documents and maximize amounts .

Why entrust your project to AirGreen?

• Mastery of Montreal buildings (plexes, flat roofs, membranes, access);

• Ingenious methodology: short route, watertight penetrations, deep void ;

• Aesthetics and durability : UV channels, suitable supports, vibration management;

• Responsive after-sales service and planned maintenance ;

• Interventions throughout Greater Montreal : Montreal , Laval , Longueuil , North Shore , South Shore .

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In short
This Sharp wall-mounted heat pump installation on a flat roof in Rosemont–La Petite-Patrie combines winter performance , membrane protection, and silence . The home benefits from stable heating in the middle of winter and efficient air conditioning in the summer, with careful and sustainable integration—exactly the AirGreen approach.