A discreet condenser on a flat roof, designed for the river's microclimate
In the heart of the Old Port of Montreal , we are integrating a Sharp wall-mounted heat pump (ZU1 series, R-32) into a plex/light commercial building. The outdoor condenser is located on a flat gravel roof , near the river and the Jacques-Cartier Bridge , an area exposed to winds and rapid temperature variations. The objective: to offer four-season comfort to occupants while respecting the architectural constraints and the emblematic nighttime urban landscape of the area.
The site and its specific constraints
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Flat roof with membrane under gravel, access via interior hatch.
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Prevailing wind coming from the river and high humidity variations .
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Shared machine park : other nearby HVAC units require standard clearances for air intake and discharge.
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Short, protected technical path to the interior head installed under the ceiling in the living area.
Choice of range and sizing
We select the Sharp ZU1 series , a wall-mounted heat pump known for:
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its stable inverter modulation ,
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its high seasonal yield ,
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its R-32 compatibility (better heat transfer and reduced footprint),
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Sharp's Plasmacluster technology that improves indoor air quality.
After calculating the load, taking into account the envelope, orientation, and occupancy, a nominal capacity of 12,000 BTU meets the needs of the service area, while leaving room for summer peaks. The unit maintains useful performance in cold weather, an essential criterion in Montreal.
Structure and support: stability above all
To protect the membrane and absorb vibrations, we place the condenser on a galvanized steel trestle attached to treated wooden sleepers resting on insulating soles (high-density foam panels) which distribute the load on the gravel.
Our flat roof support principles:
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No perforation in the membrane: all charges are diffused by continuous support.
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Clearance under the unit to prevent snow accumulation and facilitate water drainage.
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Silent blocks at contact points to limit vibration transmission to the building.
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Fan orientation away from obstacles for clear airflow .
Electricity and safety
In the immediate vicinity of the condenser, we install an external disconnect switch in a waterproof box (visible in the photo), compliant with the Code requirements. The dedicated line comes from the main panel with a rated circuit breaker . Grounding and cable management are careful to ensure longevity and safety during maintenance operations.
Refrigeration connections and sealing
The insulated copper pipes take a short, straight route: exit onto the roof via a roof cap with a watertight cable gland, then covered descent on the interior facade side to the head.
Essential steps:
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Flaring carried out using a calibrated tool and tightening to the prescribed torque .
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Deep vacuum (< 500 microns) and vacuum resistance test .
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R-32 charge supplement adjusted according to actual length.
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Reconstruction of the vapor barrier and sealing to prevent any moisture infiltration.
Positioning relative to other units
The roof accommodates several pieces of equipment. We strictly adhere to:
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suction/discharge clearances ,
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non-recirculation of hot air,
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a service corridor for technical intervention.
This arrangement avoids efficiency losses due to short-circuited air and simplifies maintenance.
Instrumented commissioning
Our technicians carry out:
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electrical verification (voltages, current under load),
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superheat/subcooling measurement,
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stabilization of the compressor frequency in test mode,
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balancing the shutters inside to distribute the air without direct draft.
The result is a rapid and consistent increase in comfort, with controlled exterior noise levels despite the urban environment.
Climate Resilience of the Old Port
Roofs near the river experience strong winds , sea spray and freeze/thaw cycles . Our configuration protects the equipment:
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Increased height under the unit to prevent snow drifting.
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Optimized orientation to limit the impact of the wind on the propeller.
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Stainless steel fasteners and galvanization for corrosion .
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On request, it is possible to add wind deflectors or snow guards if the history requires it.
Benefits for the occupant
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Economical heating during the off-season and winter support depending on the insulation.
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Quiet and stable air conditioning in summer, even during hot urban episodes.
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Improved air quality thanks to Sharp's Plasmacluster .
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Minimal visual impact from the street: condenser camouflaged by the acroterion and noise diffused towards the sky.
HVAC Maintenance: The Key to Long-Lasting Performance
For a wall-mounted heat pump on a flat roof, we recommend:
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Annual inspection in mid-spring: cleaning exchanger/fan, tightening terminals, checking disconnector.
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Wash the inner head filters every 4 to 8 weeks depending on use.
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Winter clearances : Check that no snowdrifts are reducing air intake.
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Checking of the hoods and re-sealing of the crossings every two years.
Grants and Eligibility
High-efficiency wall-mounted heat pumps using R-32 may be eligible for certain assistance programs in Quebec, subject to seasonal performance and low-temperature heating criteria. Our team assists clients in Montreal, Laval, Longueuil, the North Shore, and the South Shore to prepare applications and maximize assistance when the selected equipment meets the requirements.
AirGreen Usage Tips
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Stable setpoint (21°C in heating, 24–25°C in air conditioning) to promote modulation.
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Avoid Auto mode during mid-seasons in favor of dedicated Heating or Cooling .
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Open doors in the home to take advantage of the air circulation.
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Program an auto or medium speed for a comfort/efficiency compromise.
Why AirGreen in the Old Port and Greater Montreal
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RBQ certified teams , trained in new generation refrigerants.
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Methodology : load calculation, instrumented commissioning, compliance photos, customer report.
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After-sales service : HVAC maintenance , optimization of settings, original parts.
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Coverage : Montreal , Laval , Longueuil , North Shore , South Shore .
Flat roof project quick guide
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Type : Sharp ZU1 series wall-mounted heat pump (R-32).
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Indicative capacity : ≈ 12,000 BTU according to load calculation.
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Support : galvanized trestle on sleepers + insulating soles , silent blocks.
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Electricity : waterproof disconnect switch within easy reach, dedicated circuit.
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Refrigeration : deep vacuum, adjusted load, sealed crossings.
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Context : flat roof of the Old Port , managed wind exposure, discreet integration.
Are you looking for a reliable and aesthetically pleasing HVAC installation on a flat roof in the city center? Our teams respond quickly to the Old Port and throughout Greater Montreal, providing durable, efficient, and easy-to-maintain solutions.