Winter performance, discretion on a flat roof and optimized route: our recipe for 4-season comfort in Montreal
Context: a typical Rosemont plex, summer and winter comfort sought after
In this project, we are working on a plex-type building in Rosemont–La Petite-Patrie , a densely populated area with brick facades and flat roofs. The occupants wanted a quiet, energy-efficient HVAC solution that was especially suited to Montreal's hotter summers and winters. Their priority: increasing comfort room by room without transforming the building envelope or cluttering the courtyard. The Zephyr wall-mounted heat pump is a compact, efficient, and architecturally sound solution.
Why a Zephyr wall-mounted heat pump here?
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4-season efficiency : a heat pump provides air conditioning in summer and heating in mid-season and mild winter, reducing the use of resistive systems.
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Minimally intrusive HVAC installation : a short route between the indoor head and the outdoor unit, with very little visual impact on the facade.
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Silence : indoor units and outdoor condenser with low noise level, ideal for dense urban areas.
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Modularity : possibility of adding other areas later if the use evolves (additional bedroom, office).
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Current eligibility for high-efficiency heat pump support programs when technical criteria are met.
Sizing: Comfort begins with load calculation
Before any quote, we perform a load calculation taking into account the orientation, glazed surfaces, insulation, and waterproofing. In a Montreal plex, the target power is often between 9,000 and 18,000 BTU/h per zone depending on the volumes and solar gains. This precise sizing avoids:
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oversizing (short cycles, less dehumidification, unnecessary noise),
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undersizing (discomfort during peaks of heat or cold).
The model and power are thus chosen to stabilize the temperature and lower the relative humidity in summer.
Salient installation details: a flat roof installation designed to last
We position the condenser on the flat roof , a particularly relevant solution in the central districts of Montreal :
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Galvanized support on wooden rails placed on pads and protective membranes to distribute the loads without damaging the roof.
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Clearances respected on the air intake and exhaust side, to guarantee performance and facilitate HVAC maintenance .
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Anti-vibration treatment at the supports to limit any structural transmission.
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Refrigeration path management : insulated refrigerant lines, neatly routed to the parapet, then connected to the interior header. The length remains contained to maintain efficiency.
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Dedicated electrical path , compliant with local standards, with appropriate circuit breaker and service disconnect accessible from the roof.
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Wind orientation and shading taken into account to promote heat exchange and limit the accumulation of debris.
On flat roofs, we also think about winter:
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Sufficient support height to maintain clearance during snow accumulations.
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Position away from areas of frequent shoveling and snow avalanches.
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Free space for the flow and evaporation of defrosting .
Interior route: cleanliness, accessibility, silence
Inside, the wall-mounted fan is positioned to cover the main living area, without blowing directly onto the occupants. We ensure:
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a careful drilling with a watertight bulkhead,
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a correct slope for condensate drainage in air conditioning mode (gravity when possible, silent pump as an alternative),
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a refrigeration connection carried out in pairs, brazing under nitrogen if necessary, deep vacuum and leak testing,
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a discreet finish at the exit point.
Commissioning: protocols and measures
Commissioning includes:
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Vacuum draw until the correct pressure and hold are reached, then stability test.
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Electrical check (polarity, tightening, load intensity).
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Functional control in cooling and heating: blown temperatures, delta T, operating pressures, behavior of the compressor and fan.
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Setting of intelligent modes (setpoint maintenance, automatic restart, optimized defrosting).
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Explanations to the customer: good usage practices , setpoint and air flow settings to combine comfort and efficiency.
Concrete result for the client
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Uniform comfort in the rooms served, notable drop in humidity during humid summer periods.
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Aesthetic discretion : nothing on the facade, no occupation of the courtyard.
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Simplified technical access : the roof-mounted unit allows for quick maintenance without disturbing occupants.
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Energy savings compared to window air conditioners and resistive space heaters.
Best practices on flat roofs: what we do systematically
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Load distribution : wooden rails and protective pads, respecting the existing membrane.
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Line management : UV-resistant insulation and clean fasteners to prevent friction.
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Installation height : sized to allow the unit to breathe in winter.
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Electrical routing : dedicated circuit breaker, roof disconnect and adequately gauged wiring.
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Maintenance plan : filter, exchanger, tank, turbine, seasonal checks.
HVAC Maintenance: Simple Schedule to Maintain Performance
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Spring : complete cleaning of the outdoor unit (fins, basin), check of the fixings, cold start test.
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Summer : dusting of internal filters and checking of condensate flow.
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Autumn : Check clearances around the outdoor unit and test heating.
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Winter : clearing of snow if accumulation, visual inspection of vibrations and frost.
Annual maintenance carried out by our technicians helps maintain performance, extend lifespan and maintain acoustic benefits.
Grants and Compliance
High-efficiency heat pumps are regularly eligible for provincial and municipal assistance programs . We assist our clients in verifying eligibility and preparing applications when the chosen configuration meets the current criteria (seasonal efficiency, cold weather performance, installation by a licensed contractor).
Safety and regulatory compliance
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Work carried out by an RBQ licensed team, compliance with electrical and mechanical standards.
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Documented leak testing and vacuum testing .
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Clearly identified disconnection and clear access for the service.
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Compliance with installation rules (discharges, neighborhood, maintenance, noise).
What sets AirGreen apart in urban projects
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Flat roof control : choice of support, membrane protection, snow management and de-icing.
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Clean finishes : well-thought-out refrigeration path, clean fasteners and penetrations, preserved aesthetics.
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Complete support : from study to commissioning , then maintenance .
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Usage tips geared towards sobriety: stable setpoint, adjusted flow rates, time programming, preventative maintenance.
Practical advice for occupants
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Maintain a stable setpoint (avoid sudden variations).
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Use the dehumidification mode on humid days for added comfort.
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Maintain clearance around the outdoor unit and indoor vents.
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Schedule annual HVAC maintenance : the best way to ensure consistent comfort and controlled operating costs.
In summary
This HVAC installation showcases the benefits of a wall-mounted heat pump in an urban setting: efficiency, quietness, discreet routing, and simplified service. On a flat roof in Montreal , choosing the right support, protecting the membrane, managing clearances, and rigorous commissioning make all the difference. The result: 4-season comfort, lower bills, and a seamless integration with the architecture of Rosemont–La Petite-Patrie .
Need a similar project in Montreal, Laval, Longueuil, North Shore or South Shore?
Our teams support building owners and managers for wall-mounted, multi-zone, and central heat pump installations , with the same technical standards and attention to detail. Let's talk about your building and your comfort goals: we will propose a clear, sustainable, and scalable solution.