A flat roof HVAC installation designed to last, serving Montreal's comfort
In a residential building in the Sud-Ouest district , we installed a Haxxair wall-mounted heat pump with a condenser installed on a flat roof . The project required a clean, quiet installation that was resistant to the climatic conditions of Greater Montreal . Our team designed an optimized cooling path, a stable base on the roof, and meticulous commissioning to ensure efficient heating in winter and effective air conditioning in summer .
Background and objectives
The client wanted to modernize their system to reduce operating costs and improve comfort in a two-story 5 1/2-bedroom apartment. The constraints included access via a roof hatch, airflow potentially obstructed by gravel, and co-ownership rules requiring a discreet and reversible HVAC system . We selected a single-zone Haxxair , ideal for a Montreal apartment, with a compact wall-mounted indoor unit and an outdoor condenser on the roof.
What distinguishes a flat roof installation in downtown Montreal
The roofs of plexes and buildings in the Southwest (Saint-Henri, Little Burgundy, Griffintown) require specific technical choices. Our methodology:
Mechanical seating and vibration management
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Installation of the condenser on structural pads with anti-vibration pads to prevent the transmission of noise to the structure.
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Raising the unit above the gravel to ensure even airflow and prevent meltwater build-up.
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Orientation of the batteries to limit the recycling of hot air in air conditioning mode and promote defrosting in heating mode.
Refrigeration path and sealing
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Routing of the refrigerant lines from the interior head to the technical column , then crossing the roof using a waterproof roof pass-through.
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Restoration of the air barrier and vapor barrier in accordance with good practices, in order to prevent infiltration and condensation in the envelope.
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Communication cabling and power supply grouped and secured under cover for a neat and durable finish.
Condensate management
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Gravity evacuation of the interior head, local services allowing a constant slope; as a backup, a low-noise lifting pump would have been provided.
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Provision for winter clearance of the condenser for defrost water, essential for any heat pump operating in cold weather.
Rigorous commissioning by AirGreen
Our technicians apply the same discipline on each site, whether in Montreal, Laval, Longueuil, North Shore or South Shore .
Nitrogen leak test
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Pressurization of the lines with dry nitrogen to validate the absence of micro-leaks at the beaten collars and flare connections.
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Stabilization measured during an interval representative of thermal variations on the roof.
Deep vacuum draw
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High vacuum with pump and digital vacuum gauge to reach a micron level attesting to a perfectly dehydrated circuit.
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Refrigerant breakage and vacuum maintenance without rebound: a guarantee of compressor performance and longevity.
Configuration and functional testing
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Checking load currents, temperature differences (flow/return) and defrosting strategy in heating mode.
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Adjustment of ventilation speeds on the interior side to optimize acoustic comfort and seasonal efficiency.
Why choose Haxxair for a Montreal apartment?
Even without referencing a specific model , the Haxxair wall units used by AirGreen are distinguished by:
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An exchanger sized for good air conditioning performance and heating performance in cold weather.
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An inverter control to modulate power and limit on/off cycles.
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Contained acoustics , essential in a dense urban environment.
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Efficient defrosting electronics, reducing cycle times and maintaining stable comfort .
Depending on the selected BTU capacity and efficiency (SEER/HSPF), these appliances may be eligible for certain financial assistance programs . We always validate, on a case-by-case basis, the eligibility of projects in Montreal, Laval, Longueuil, North Shore and South Shore .
Highlights of this construction site in the Southwest
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Haxxair condenser installed on a flat roof with anti-vibration riser.
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On-site commissioning tools : manifold, vacuum gauge, vacuum pump, nitrogen bottle for pressure testing.
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Disconnect box installed nearby (outside water stagnation areas), protected cable and tight routing.
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UV coating on the connections, consistent with the color of the roof accessories.
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Finishes: stainless steel attachments and sealed roof passage for lasting watertightness .
Result for the customer
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Rapid rise in comfort from the first minutes in air conditioning.
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Thermal stability in heating despite the temperature fluctuations typical of the Lachine Canal.
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Minimal noise in the home thanks to vibration decoupling and fine adjustment of the fan speed.
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HVAC maintenance clarified: washable interior filter, seasonal inspection, coil cleaning and connection verification.
Good practices and pitfalls to avoid on roofs
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Never place a condenser directly on the gravel : this accelerates corrosion and disrupts the air intake.
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Systematically protect the roof passage: air barrier, vapor barrier and membrane-compatible sealant .
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Provide winter drainage for defrost water; on roofs, avoid areas of accumulation.
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Install an external circuit breaker and check the grounding .
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Plan annual maintenance : cleaning, checking pressures/parameters, leveling supports.
AirGreen expertise in Greater Montreal
AirGreen supports condominiums, plexes and individual homes with adapted HVAC solutions: wall-mounted heat pumps , multi-zone , central systems , quality accessories and responsive after-sales service. Our teams master the varied contexts of Montreal intramural , as well as the logistical requirements of Laval , Longueuil , the North Shore and the South Shore . Each project is documented, tested and delivered with clear instructions for use and maintenance.
Maintenance recommended to maintain performance
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Bi-monthly filter cleaning during peak season.
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Gentle washing of the interior evaporator and inspection of the condensate drain.
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Dusting the condenser and checking the horizontality of the supports.
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Checking electrical parameters and tightness of connections.
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Annual HVAC maintenance report: it extends the lifespan and maintains seasonal performance .
Conclusion
This Haxxair installation on a flat roof in southwest Montreal demonstrates the benefits of a structured approach: stable mechanical foundation, sealed refrigeration path, instrumented commissioning and a clear maintenance plan. The result: four-season comfort , controlled consumption and discreet integration, perfectly adapted to Montreal's urban fabric.