A flat roof installation designed for the Montreal climate and four-season comfort
At AirGreen , we just completed the installation of a TOSOT wall-mounted heat pump for a typical Rosemont–La Petite-Patrie duplex. The owner's goal was clear: to ensure stable comfort in both summer and winter , without encroaching on the interior space, while respecting the flat roof membrane and local electrical and HVAC standards. We opted for a 12,000 BTU single-zone configuration perfectly sized for the main living area, with a condenser installed on the roof and a wall-mounted head positioned in the most occupied room.
Client background and objectives
The client wanted:
-
Rapid cooling during Montreal heat waves and efficient heating during the off-season;
-
A discreet exterior layout , freeing up the backyard;
-
Low noise level both indoors and outdoors;
-
A durable installation, compatible with simple annual HVAC maintenance .
Why the TOSOT brand for this project?
TOSOT (GREE group) offers reliable wall-mounted heat pumps , stable in low-temperature heating mode, and appreciated for their silence and seasonal efficiency . On this type of Montreal building – brick walls, exterior staircase, flat roof with elastomeric membrane – the combination of wall-mounted head + roof condenser is often the most judicious: it protects the equipment from ground impacts, reduces fouling by street dust and frees up space at the facades.
Careful installation on a flat roof: stability, drainage and longevity
Supports and anti-vibrations
The condenser is placed on raised pads (concrete bases and anti-vibration pads) in order to:
-
Dissipate vibrations and preserve the peace of mind of occupants;
-
Elevate the unit to avoid water accumulation during rains;
-
Facilitate occasional snow removal in winter around the device.
Respect for the membrane
We systematically protect the roof membrane: controlled routing, no unnecessary drilling , and clearance around the unit to allow water to flow away . This method prevents stagnation and preserves the integrity of the waterproofing , a major point on Montreal plexes.
Clearances and air circulation
We have reserved compliant clearances on the rear and sides of the condenser in order to optimize:
-
The air flow through the exchanger;
-
Heating performance during defrost cycles;
-
Accessibility for maintenance (washing the coil, checking connections).
Connections: cleanliness of the route and guaranteed performance
Refrigerant lines and insulation
The lines run along a short, clear path, with high-density insulation on the liquid and gas, then a protective cover near the outdoor unit. A nitrogen pressure test is carried out before vacuuming to ensure tightness and prevent any micro-leaks.
Condensate management
In cooling , the condensates from the indoor unit are drained by gravity to the outside, which eliminates the need for a pump and reduces the risk of breakdown. In heating , the water from the defrost cycles flows freely onto the roof; we keep a clear area to prevent refreezing at the foot of the unit.
Power supply and electrical safety
The installation includes a disconnect box in the immediate vicinity of the condenser (visible in the photo), a dedicated circuit from the main panel and RBQ/CSA compliant protections . This device makes maintenance interventions safe and protects the equipment against power surges.
Inside: comfort, silence and even diffusion
The wall-mounted fan head is positioned to sweep the living area without blowing directly onto the occupants. Thanks to the inverter , the machine finely modulates its power: the temperature stabilizes quickly and the noise level remains very low . For a bedroom or open living room, the 12,000 BTU offers an excellent compromise between responsiveness and energy efficiency .
Commissioning and performance checks
Our technicians carry out:
-
Nitrogen test (high pressure) and leak test;
-
Deep vacuum draw down to a stable micron level;
-
Opening the fluid and checking the refrigeration parameters using a manifold;
-
Measurement of supply/return temperature differences ;
-
Setting the shutters and thermostat for optimal perceived comfort.
This protocol ensures that the TOSOT heat pump delivers the expected performance from day one.
Winter in Montreal: Best Practices to Protect Your Investment
-
Snow/ice clearance : keep a clear perimeter around the condenser to ensure air intake and exhaust during defrost cycles .
-
Snow guard if necessary : on certain exposed roofs, a mini deflector can prevent snow from accumulating directly on the device.
-
Coil Cleaning : A gentle wash in spring restores heat exchange and improves seasonal efficiency (SEER/HSPS).
-
Annual HVAC maintenance : electrical check, tightening of terminal blocks, checking of line and drain insulation.
Subsidies and energy efficiency
Depending on the configuration chosen ( certifications and performance ranges ), this type of wall-mounted heat pump may be eligible for provincial incentives . We systematically evaluate:
-
The existing consumption profile ;
-
The building envelope (windows, air infiltration);
-
The eligibility criteria in force.
Our team prepares a clear case to help the client maximize savings over the life of the system.
Measurable result: comfort, silence, controlled bill
Upon start-up:
-
The indoor temperature stabilizes quickly, even in the late sunny afternoon;
-
The noise perceived near the facade and inside remains very low ;
-
Directional blowing improves room homogeneity, limiting hot/cold areas .
The owner now benefits from four-season comfort , reduced operating costs and a visually clean installation, with no ground equipment in the yard.
What sets AirGreen apart for flat roof projects in Montreal, Laval, Longueuil, North Shore and South Shore
-
Precise sizing (BTU and location) according to the reality of the building and not a generic table;
-
Strict compliance with clearances, sealing and electrical standards ;
-
Neat finishes : insulated lines, clean hood, accessible disconnection ;
-
Instrumented commissioning (nitrogen, vacuum, actual measurements);
-
After-sales service and planned HVAC maintenance .
Practical advice for future projects in urban areas
-
Favor the roof when the facades are limited: better discretion and cleaner air flow .
-
Plan for winter from the design stage: clearances, snow removal access, water drainage from defrosting cycles.
-
Maintain annually : simple maintenance preserves efficiency and extends lifespan.
-
Take care of the power supply : dedicated circuit, disconnect box , RBQ/CSA compliance.
-
Choose a proven brand : TOSOT offers an attractive quality/price/performance ratio for plexes and duplexes in Greater Montreal.
AirGreen supports owners and managers in Montreal, Laval, Longueuil, and on the North and South Shores for durable, aesthetic, and efficient HVAC installations . For a similar project in Rosemont, or to assess the potential of your building, our team takes care of the entire process , from choosing the wall-mounted heat pump to commissioning and annual maintenance .
AirGreen — your local partner in heat pumps , wall-mounted air conditioners and HVAC installations in Greater Montreal.