Four-season comfort in a double-height staircase
At AirGreen , we have just installed a Gree wall-mounted heat pump (recent R-32 range) in a plex-type house in Plateau-Mont-Royal . The indoor unit is located above an air-gap staircase , a strategic location for circulating the entire volume of the ground floor and the upper floor while freeing up the living walls. Our mission: to offer stable comfort in summer and winter, with clean and sustainable HVAC integration in an interior architecture combining exposed brick and glass railings.
The context: open spaces, stratified heat and noise to control
Open-plan rooms generate two realities:
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air stratification (warm air rises, cool air stagnates),
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noise reverberation if the devices are not properly sized.
So we have:
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chose a wall head positioned high under the ceiling to capture the accumulated hot air and circulate it on both levels;
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adjusted the blowing angle to sweep the stairwell without “direct blowing” onto the passage area;
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used silent blocks and tightening to the prescribed torque to contain vibrations.
Device and configuration selected
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Type : wall-mounted heat pump (mini-split) — air conditioning and heating .
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Brand : Gree .
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Range : recent R-32 (low temperature performance, inverter compressor).
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Capacity : sized for the stacked volumes of the staircase and adjoining living room (typical 9k–12k BTU range for this type of space depending on the envelope).
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Efficiency : inverter technology for finely modulating power — savings at partial load and acoustic comfort.
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Refrigerant : R-32 , with lower global warming potential than R-410A, and better heat exchange.
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Winterization : automatic defrosting and heating base of the condenser when required by the range; heat retention down to −25°C (depending on the sub-model in the range).
Dimensional note: the exact load (BTU/h) results from a calibration on the actual envelope (orientation, windows, masonry, insulation and sealing). We systematically apply a thermal calculation before recommendation.
HVAC installation procedure
1) Structural fixing and laser tracing
In a stairwell, precision is non-negotiable. We have:
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located the studs behind the plasterboard;
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used a template and a rotating laser for perfect alignment;
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validated the ceiling clearance to allow the hood to be opened and for future maintenance.
2) Discreet refrigeration route
The interior aesthetics being neat ( brick wall on one side, gallery of frames on the other), we have:
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routed the insulated copper connections through the back of the wall, then to the ceiling, in order to avoid any visible cover in the shaft;
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installed a discreet exterior capping (color matching the masonry), with curvature radii respected to preserve the oil column;
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made a single hole with a slight gravity slope and installed a watertight bulkhead (vapor barrier).
3) Condensate management
At this height, a gravity drain is not always realistic. So we have:
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installed a compact and quiet condensate pump integrated into the casing;
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provided with an anti-siphon and a vinyl tube resistant to micro-vibrations;
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added an accessible in-line filter for seasonal maintenance.
4) Outdoor condenser designed for Montreal
The wall condenser is:
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placed on galvanized brackets with snow clearance (> 30 cm from the finish);
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detached from the masonry by anti-vibration pads;
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protected by a snow deflector when exposure requires it;
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connected to an external circuit breaker and a circuit breaker dedicated to the panel.
5) Commissioning and checks
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Deep vacuum with digital vacuum gauge (< 300 microns stabilized), nitrogen leak test, re-tightening to torque on collars;
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Commissioning : verification on heating and air conditioning mode , ΔT reading, voltages, currents, subcooling/superheat according to the recommended method;
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Thermostat calibration and swing curves to avoid short cycles.
Result: consistent comfort and appreciable silence
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The stairwell becomes a natural plenum that redistributes air over two levels.
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Inverter modulation reduces temperature variations and keeps noise levels to a minimum—a crucial point in reverberant spaces (brick, glass, high ceilings).
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Integration without visible interior cover preserves aesthetics .
HVAC Use and Maintenance Tips
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Filters : rinse them every 4 to 6 weeks in summer; more often if there are animals or construction dust.
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Condenser fins : gentle rinse in spring; maintain clearance around the unit.
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AUTO mode vs HEAT/COOL : in the off-season, choose dedicated HEAT or COOL to avoid frequent switching.
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Professional cleaning : complete annual maintenance (mild chemicals, tank, turbine, drain, pump) protects the exchanger and maintains performance.
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Remote/App : Schedule time slots ; continuous low speed limits stratification.
Grants and Compliance
Recent R-32 and high-efficiency wall-mounted heat pumps may be eligible for assistance programs in Quebec when their performance meets the required thresholds (low-temperature heating, performance certification). We guide you:
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verification of eligibility criteria according to power and efficacy indices;
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provision of installation documents and proof of commissioning ;
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support for Montreal, Laval , Longueuil , North Shore and South Shore .
Pitfalls to avoid (AirGreen feedback)
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Undersize in a double-height volume: the device will turn too quickly, make noise and wear out prematurely.
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Unsecured drain : a poorly installed pump ends up vibrating and clogging the tank; we always add absorbers and non-return loops .
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Out-of-torque collars : slow leaks, pressure loss; at AirGreen, the torque is measured and recorded.
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Condenser too low : risk of freezing and snow suction. We respect the recommended increases and defrost management .
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No circuit breaker : we install a compliant external disconnect , essential for safety and maintenance.
Why choose AirGreen in Plateau-Mont-Royal?
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Local HVAC expertise : mastery of the particularities of Montreal plexes (brick, beams, narrow cages).
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Path engineering : invisible solutions (in wall/ceiling) or matching cover if invisible is not possible.
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Measurable quality : documented vacuum, sealing and commissioning protocols.
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Full service : on-site estimation, planning, installation, HVAC maintenance and grant support.
What if you're unsure about power or range?
We carry out a simplified thermal assessment during the visit, then we recommend one of the suitable Gree R-32 ranges (e.g. Livo, Clivia, Vireo, Sapphire depending on the configuration), or an alternative from Fujitsu or Midea if your priorities are very cold , native connectivity or record noise levels . The objective remains the same: uniform comfort throughout the house, without visual compromise.
