Four-season comfort for an urban building: an exemplary HVAC installation on a flat roof
Project background
In a residential building in Southwest Montreal , one of the co-owners entrusted us with the installation of a wall-mounted heat pump to ensure precise cooling in the summer and economical heating in the mid-season. The building has a flat gravel roof with several outlets (chimneys, air intakes, vents). The objective: to install a Zephyr condenser on the roof, properly connect the refrigeration lines to the indoor head and guarantee maximum reliability without compromising the roof's watertightness or disturbing other occupants.
Why choose Zephyr for an urban roof
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Inverter technology : fine modulation of the compressor, energy saving and stable temperature.
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Compact footprint : format suitable for cramped technical areas and shared roofs.
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Controlled acoustics : fan and shroud optimized for discreet operation , essential in co-ownership.
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Easy maintenance : easy access to panels and parts supply available locally via our network.
AirGreen Implementation: What We Achieved on This Flat Roof
Preliminary study and implementation
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Survey of clearances around the outlets in order to distance the unit from stale air discharges (kitchen/bathroom) and fresh air intakes.
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Orientation of the blowing away from obstacles to avoid recirculation of hot air in air conditioning mode and maintain optimal heat exchange.
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Protected path for technicians: we provide a service corridor free of any obstacles, useful for periodic maintenance.
Support on raised stand
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Galvanized steel structure mounted on blue anti-vibration pads to limit solid transmissions to the building.
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Distribution soles placed on the gravel with treated wooden wedges fixed on plates to distribute the load and resist freezing and thawing.
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Increased ground clearance : The height of the stand keeps the unit above snow accumulation and puddles, while clearing the suction and discharge.
Refrigeration and electricity connections
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Optimized route via an existing technical chimney : no new opening in the membrane; we take a sealed passage already provided for the services, then go back down towards the apartment.
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Estimated total length: 12 to 18 meters , perfectly compatible with Zephyr recommendations (with addition of refrigerant if necessary depending on the actual length).
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Insulation of both lines with high-density foam and UV tape to resist solar rays and temperature variations.
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Communication cable and dedicated power supply on separate circuit breaker; external disconnect installed in close proximity to the condenser in accordance with code.
Condensate management
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Exterior side : the condenser drains directly onto the roof; we check the flow towards the rain inlets to avoid puddles under the unit.
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Interior side : gravity drainage preferred with continuous slope to the outlet point; if the architecture requires it, a silent, anti-siphonage condensate pump is provided.
Roof waterproofing and durability
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Zero unnecessary perforation : connections passed through the technical duct with fire-resistant sleeves at the floor crossings.
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Stainless steel hardware and cold galvanized paint on the cuts to prevent corrosion.
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Mechanical protection of insulation and cables by UV ducts in areas exposed to trampling.
Rigorous commissioning
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Nitrogen test with leak detection (soap + pressure gauges) along the entire line.
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Deep vacuum draw until stabilization, then test rise to confirm absence of humidity.
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Opening of valves and reading of temperatures/pressures in cooling and heating modes.
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Acoustic and vibration controls on the stand.
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Occupant training : methods, instructions, filter maintenance, good winter practices.
Results: real efficiency and urban comfort
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Uniform cooling of the living area, without aggressive air currents thanks to Inverter modulation.
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Efficient supplementary heating in spring and autumn; in colder periods, the heat pump significantly reduces the need for electric heaters.
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Silence : the noise level remains contained for neighbors on adjacent roofs and occupants of the top floor.
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Aesthetics : the condenser, aligned with the other roof equipment, respects the architectural framework and leaves maintenance access clear.
AirGreen Tips for a Flat Roof Heat Pump in Montreal
Good usage practices
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Stable settings : let the inverter work; avoid too frequent setting deviations.
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Clearances : keep 1 m free in front of the discharge and clear the rainwater inlets.
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Defrosting : In winter, do not turn off the power; let the machine manage its cycles.
Maintenance and inspections
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Inner head filter : clean every 4 to 8 weeks.
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Annual inspection by AirGreen: checking pressures , evaporator/condenser , tightening electrical terminals , checking the membrane around the technical passage.
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After the storm : confirm that no gravel or debris is obstructing the grid; check the stability of the pads .
Common Mistakes to Avoid (and How We Prevent Them)
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Condenser too close to an air outlet (hood/kitchen) → risk of battery lubrication and reduced efficiency: we measure and reposition if necessary.
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Direct support on the membrane → punching: we use dimensioned soles and distributor pads.
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Oversizing of BTU capacity → short cycles: we size according to the surfaces, the sunshine and the actual insulation.
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Poorly designed interior drain → leaks and stains: controlled slope, anti-odor elbows and load tests.
Grants and Eligibility
High-efficiency wall-mounted heat pumps may be eligible for certain programs in Quebec, subject to the low-temperature operating range and certified efficiency levels. Our team supports clients in Montreal , Laval , Longueuil , the North Shore and the South Shore to verify eligibility and prepare applications when the interior/exterior assembly meets the current criteria.
Why entrust your project to AirGreen?
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Mastery of Montreal flat roofs : access logistics, membrane protection, management of clearances and prevailing winds.
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Clean finishes : continuous UV coating , stainless steel fixings, rigid and leveled stand , documentation provided to the customer.
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Full Service : HVAC installation , HVAC maintenance and fast after-sales service on Zephyr and other popular brands.
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Extensive coverage : interventions in Montreal , Laval , Longueuil , as well as on the North Shore and the South Shore .
Express FAQ
Is a rooftop unit noisier?
No, a well-designed anti-vibration mount and sufficient clearances maintain a very low noise level for occupants and neighbors.
What happens in winter?
The raised stand keeps the unit above snow. Defrost cycles protect the exchanger; a clear service passage is sufficient for winter maintenance.
How long does the installation take?
In a building with roof access, one day is generally sufficient for installation, emptying , testing and commissioning .
Keywords : heat pump , wall-mounted heat pump , Zephyr , HVAC installation , HVAC maintenance , Montreal , Laval , Longueuil , North Shore , South Shore .