A flat roof project, executed to perfection for four-season comfort in Rosemont
Client context and objectives
In Rosemont–La Petite-Patrie, the owner of a recent plex commissioned us to modernize his HVAC comfort with a Sharp ZU1 series wall-mounted heat pump ( R-32 technology, inverter compressor) to ensure quiet cooling in the summer and efficient heating even in the coldest weather. The building has a flat elastomeric membrane roof ; the optimal location for the outdoor condenser is therefore on the roof, to free up the courtyard and reduce noise transmission to neighbors.
Our mission: to deliver a clean, durable HVAC installation that complies with best roofing practices, minimizing drilling and optimizing the length of refrigerant lines to maintain energy efficiency.
Why the Sharp (ZU1 range) for an urban plex?
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High seasonal efficiency thanks to the inverter compressor and R-32 fluid, more efficient and with lower GWP than previous generations.
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Cold weather heating : the ZU1 range is designed to maintain useful capacity below zero, a major asset for Montreal , Laval , Longueuil , North Shore and South Shore .
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Silence and air quality : the Sharp ecosystem is distinguished by the care taken with acoustics; inside, the wall head offers homogeneous diffusion and easy-to-maintain filters.
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Eligibility for efficiency programs : a high-performance, certified heat pump facilitates access to energy efficiency subsidies in effect in Quebec (depending on criteria and availability).
Key steps in HVAC installation on a flat roof
1) Roof survey and layout plan
We validate:
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the state of the membrane ,
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the direction of the prevailing winds and obstacles (low walls, vent outlets),
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the ideal routing of refrigeration lines and power supply from the wall head to the condenser.
The chosen layout protects the unit from return air, promotes the evacuation of defrost water and respects the setbacks for maintenance.
2) Roof support: stability, load distribution and membrane protection
The Sharp condenser rests on a raised galvanized support , fixed to pads placed on an insulated distribution plate of the rigid panel type (DuroSpan), in order to:
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distribute the load and avoid any pressure peaks on the membrane,
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raise the unit for better defrosting in winter and easy access to the crankcase,
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mechanically separate the unit from vibrations (anti-vibration inserts).
This installation is preferred in dense urban environments, very common in Rosemont, the Plateau or Villeray , where roof protection is non-negotiable.
3) Routing of refrigeration connections and power supply
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Optimized total distance : ~10 to 12 m between the indoor head and the outdoor unit, ideal for preserving the nominal capacity .
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Covered passage in the roof to protect the lines against UV rays and impacts.
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Single waterproof piercing at the point of penetration (compliant flashings, membrane-compatible sealants).
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Drainage : Condensate is drained from the head by gravity to the dedicated outlet point; on the roof, the unit naturally manages defrost water with the free space under the base.
4) Connections, vacuuming and integrity checks
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Brazing under nitrogen, calibrated flares, torques using dynamometers .
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Deep vacuum (< 500 microns) and leak test .
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Electrical validation (dedicated circuit breaker, conductor gauge, grounding).
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Interior head settings (speed levels, flap orientation, auto/heat/cool mode).
5) Commissioning and performance checks
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Measurements of intensity , blown/return temperatures , and subcooling/superheating .
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Acoustic verification at low speeds for the comfort of occupants and neighbors.
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Explanations of use to the customer (modes, instructions, filter maintenance, good winter/summer practices).
Salient technical details of this achievement
Flat roof: AirGreen best practices
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No unnecessary perforation : a single point of penetration, carefully sealed .
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Condenser elevation : sufficient ground clearance for snow and defrosting .
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Load distribution : rigid panel under the support to protect the membrane.
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Hood lines : UV protection and aesthetics; fewer visual heat islands.
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Short path : limits pressure losses and preserves actual SEER/HSPF .
Interior integration
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Head location chosen to sweep the main living area.
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Discreet passage of connections, clean and aligned white hood.
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Power supply on dedicated circuit, calibrated according to the nameplate.
Security and Compliance
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Compliant external circuit breaker and disconnect .
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Respect clearances around the condenser for maintenance and ventilation.
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Installation documentation provided to the customer (serial numbers, parameters).
Result: stable comfort, controlled bill, preserved roof
The client benefits from rapid cooling and reliable supplemental heating even when temperatures plummet. Power consumption remains contained thanks to the inverter and R-32 ; the roof is protected by load distribution and careful waterproofing. As a bonus, the rooftop location reduces noise perceived on the ground and frees up the aesthetics of the courtyard.
HVAC Operation and Maintenance Tips to Maximize Lifespan
In winter (Montreal, Laval, Longueuil, North Shore, South Shore)
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Maintain clearance under the unit; do not obstruct the defrost area.
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Allow the appliance to complete its defrost cycles without interrupting it.
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Maintain a stable setpoint rather than large day/night differences.
In summer
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Clean the inner head filters every 4 to 6 weeks.
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Avoid setting the settings too low ; each degree gained reduces consumption.
All year round
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Recommended annual inspection: pressure check, coil cleaning, electrical check, settings update.
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Keep the area around the condenser clear (leaves, dust, objects).
Grants and administrative procedures
High-performance, certified wall-mounted heat pumps are generally eligible for energy efficiency programs in Quebec. Conditions vary depending on the year, the type of home, and cold weather performance. Our team supports homeowners in Montreal , Laval , Longueuil , the North Shore , and the South Shore for:
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identify open programs,
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prepare technical documents (plate, serial numbers, performance sheets),
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structure the submission and installation evidence.
What makes AirGreen different for rooftop installations?
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Flat roof specialization : Montreal know-how, respect for membranes and loads.
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Clean and durable finishes : galvanized supports, aligned covers, short paths.
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Instrumented measurements and commissioning : no approximations.
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Local HVAC service and maintenance with quick access to parts.
What if your building looks like this?
Do you have a plex in Rosemont, Villeray , Le Sud-Ouest , Verdun or Plateau with a flat roof ? A Sharp wall-mounted heat pump (ZU1 range) can be a simple, efficient and discreet solution. We size the BTU capacity based on the envelope (orientation, insulation, sealing), permissible noise and line lengths. The goal: four-season comfort and controlled operating costs , without compromising on the roof.
Installation summary sheet (Rosemont project)
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Type : single-zone wall-mounted heat pump .
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Brand : Sharp ( ZU1 range, R-32, Eco Inverter ).
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Location : flat roof on raised galvanized support , rigid distribution plate .
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Route : covered roof connections; ~10–12 m.
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Drilling : single, sealed according to the rules of the art.
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Objectives : 4-season comfort, low perceived noise, preserved aesthetics, optimized performance.
Need flat roof expertise in Montreal?
At AirGreen , we combine practical engineering , strict roof compliance and instrumented commissioning . Contact us for a free estimate and precise sizing tailored to your building in Montreal , Laval , Longueuil , North Shore or South Shore .