A flat roof installation designed for the Montreal climate
At AirGreen , we offer complete HVAC solutions for plexes and flat-roofed buildings. In Rosemont–La Petite-Patrie , we are installing a Gree MultiZone Ultra Heat series heat pump, chosen for its capacity maintenance in intense cold and its stable winter heating performance. The vertical dual-fan condenser is integrated into the elastomeric roof, with a support structure that protects the membrane and ensures wind stability.
The client's need: to serve multiple areas (living room, bedrooms and office) with a single condenser, reduce summer air conditioning costs, and add efficient supplemental heating in the off-season. Our mission: to deliver a robust, quiet and durable HVAC installation , respecting the constraints of a typical building in the heart of Montreal .
Technical steps, settings and results
1) Site design and preparation
Load analysis and sizing. The Gree MultiZone configuration can power 2 to 5 indoor heads . We size the total capacity according to the actual volumes, the orientation of the rooms, the level of sunlight and the insulation. The objective is not overcapacity, but a balance that ensures long and modulated operation in inverter , guaranteeing savings and silence.
Location selection. On Montreal roofs, the orientation of the condenser relative to parapets and prevailing winds is critical. We install the unit away from immediate obstacles to ensure unobstructed airflow for both intake and exhaust, while preserving service paths. The distance from neighboring air intakes and exhausts is checked to avoid any recirculation.
Membrane support and protection. We place the condenser on a treated wooden base fixed on EPDM pads and distribution plates . This assembly:
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distributes the load without perforating the membrane;
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incorporates anti-vibration pads to limit structural transmission;
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maintains clearance under the unit to allow defrost water to drain away and prevent snow from accumulating around the base.
Power and safety. An external service switch is located near the unit, making servicing easier. The dedicated circuit from the electrical panel meets Gree's specified rating, with appropriate grounding and circuit breaker .
2) Refrigeration route and connections
Vertical routing. From the condenser, the refrigeration lines descend through the technical duct to the floors served. We favor balanced lengths between heads to improve regulation and avoid whistling noises associated with excessively high fluid speeds.
Nitrogen brazing and continuous insulation. Each joint is brazed under nitrogen to preserve the internal integrity of the copper tubes. The insulation is continuous, high-density, protected by a UV-resistant outer cap . The bend radii are respected to avoid microcracks and maintain seasonal performance.
Condensate management. In most rooms, we favor gravity drainage . When a slope cannot be guaranteed, we integrate a silent lifting pump with level detector and maintenance access.
3) Installation of interior heads and diffusion strategy
Positioning by zone. Each head is placed high up , on a clear wall, to take advantage of the sweeping effect along the ceiling and then a smooth return of air to the occupied zone. The side and top clearances recommended by Gree are respected to ensure efficient heat exchange and facilitate future maintenance.
Sound comfort. The mounts are fitted with anti-vibration spacers ; the covers are fitted to prevent any buzzing. Inverter modulation reduces the speed very quickly once the setpoint is reached, which continuously improves sound quality.
Control and usage scenarios. We configure time slots and differentiated settings per room. In bedrooms, Night mode limits variations and automatically lowers ventilation.
4) Commissioning: AirGreen protocol
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Nitrogen leak test and deep vacuum ; vacuum stability checked before opening the valves.
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Electrical check : polarities, tightening torque, current.
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MultiZone configuration : pairing of heads, balancing of priorities, test in cooling then in heating .
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Functional measurements : supply/return temperatures, pressure, subcooling/superheating.
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User training : good usage practices, reading codes and reminder of the HVAC maintenance schedule.
5) Results: multi-room comfort and real savings
After adjustments, the MultiZone heat pump offers:
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Rapid cooling of exhibits in the late afternoon, with a uniform sensation thanks to overhead diffusion.
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Highly effective supplemental heating in spring and fall; the Ultra Heat series ' capacity retention limits the use of electric baseboard heaters on cold mornings.
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Silence in stabilized mode, essential in bedrooms and work spaces.
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Consumption controlled by the inverter and by precise sizing of the heads.
6) Good practices and points of vigilance on roofs
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Clearance around the condenser : never lean the exchanger against a parapet; maintain access for service and air circulation.
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Frost management : ensure free flow of defrost to a drainage point; prevent ice formation around feet.
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Usable height : keep space under the unit for water and wind-blown snow.
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No perforation in the membrane: prefer weighted bases or bases supported on pads with load distribution.
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Cable protection : UV sheath and waterproof roof pass-through ; avoid sharp edges.
7) Recommended HVAC maintenance
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Internal filters : rinse every 2 to 4 weeks during high season; dry completely before replacing.
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Annual inspection : cleaning of exchangers, leak test, drain check, tightening of terminal blocks and checking of external seals.
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Winter : Maintain a stable setpoint to avoid short cycles; clear the area around the condenser after storms.
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Air quality : A clean filter improves performance and reduces power consumption.
8) Grants and Compliance
Several Gree MultiZone configurations meet the efficiency criteria recognized in Quebec. Depending on the exact model and active programs, the installation may be eligible for financial assistance . We provide technical documents ( AHRI number, performance sheets) and support the customer in the process for Montreal , Laval , Longueuil , the North Shore and the South Shore .
9) Why AirGreen for your MultiZone project in Montreal
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Flat roof control : anti-vibration supports, load distribution, defrosting and wind management.
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Careful execution : brazing under nitrogen, continuous insulation , balanced paths between heads.
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Sustainable monitoring : HVAC maintenance contract, parts availability and rapid interventions.
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Regional coverage : field teams throughout Greater Montreal .
10) Operational summary
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Load study and choice of capacity by zone.
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Installation of the condenser and protective roof support .
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Balanced refrigeration paths and sealing of the crossings.
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Head installation, broadcast settings and programming.
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Commissioning with measurements and training.
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Planned maintenance to preserve seasonal performance.
This Gree Ultra Heat MultiZone heat pump installation in Rosemont–La Petite-Patrie combines winter reliability, multi-room comfort, and meticulous finishes. It prepares the building for warmer summers and longer shoulder seasons, while reducing energy bills throughout the year.