Full-height comfort: a wall-mounted headboard perfectly placed in the stairwell
At AirGreen , we have just installed a Sharp ZU1 (R-32) wall-mounted heat pump in a typical Villeray house. The project's unique feature: the indoor head is positioned at the very top of the stairwell , a strategic location for circulating air between the upper and lower floors. The result: consistent comfort on two levels, with fewer cold spots in winter and faster air conditioning in summer—all in a simple, discreet integration on a light-colored wall.
Why the stairwell is a winning location
A stairwell acts like a convection column . Warm air naturally tends to rise; cool air sinks. By placing a wall-mounted heat pump at this critical point, we exploit this natural movement to:
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Distribute heat to the upstairs bedrooms without overheating the living room;
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Bring the cooled air back to the ground floor in air conditioning mode;
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Reduce temperature deltas between rooms;
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Reduce the number of short cycles and optimize electricity consumption .
To amplify the effect, we set the diffusion flaps : a slightly upward angle in heating mode to push the air towards the landing, then a horizontal sweep in summer to break up the pockets of hot air at the top of the shaft.
The chosen solution: Sharp ZU1 R-32, 15,000 BTU
Capacity and series. The Sharp ZU1 chosen here in 15,000 BTU comfortably covers an open space on two levels, typical of Villeray homes. The ZU1 series, with inverter compressor and R-32 refrigerant, offers an excellent efficiency/compactness ratio and very low noise level - ideal for a passage and rest area.
Main highlights:
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Extreme cold : stable performance down to -25°C , adapted to the Montreal climate;
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R-32 : reduced climate impact and better volumetric capacity than R-410A;
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Quiet : quiet operation; no buzzing in the stairs at night;
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Filtration : multi-filters and precise blowing, limiting direct air currents.
Installation process: clean, robust and designed to last
1) Study and preparation.
Our technicians began with a thermal assessment of the house: volumes to be treated, ceiling height, permeability of doors and corridors, occupancy habits. This allowed us to confirm the capacity of 15,000 BTU and to validate the location at the top of the wall , above the stair chases, away from the angles that block diffusion.
2) Drilling and crossing wall-to-wall.
We made a single sloping hole for gravity condensate drainage. The refrigerant connections and power cable are grouped together and sealed to prevent air infiltration. The slope ensures that the drain flows naturally to the outside, without a pump (increased reliability, reduced maintenance).
3) Finishes and aesthetics.
The connections are protected by discreet capping coordinated with the color of the wall. The old fixings visible on the wall were neatly filled ; a touch-up of paint was recommended to the client for a perfect finish. The head fixing plate is laser-leveled , preventing any vibration and condensation leaks.
4) Vacuuming and loading.
After crimping, we performed a deep vacuum and an extended leak test to ensure the absence of moisture and micro-leaks in the circuit. The ZU1's electronic parameters (line length, height compensation) were programmed according to the actual configuration.
5) Start-up and air balancing.
In commissioning, we set the automatic speed and defined two user scenes :
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Winter : upward blowing + slow sweeping to promote controlled stratification;
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Summer : almost horizontal diffusion + faster sweeping to break up the accumulation of heat in the upper part.
Integration with everyday life: measurable comfort, controlled consumption
In this project, the house had a differential of 3 to 4 °C between the landing and the living room during cold peaks. From the first week of use, the client reported a difference reduced to 1 °C , a sign of successful air distribution . In summer, fresh air precedes the occupants: when going down the stairs, you enjoy a uniform sensation of freshness , without localized drafts.
On the expense side, inverter technology limits full-power starts. The machine continuously modulates to maintain the setpoint, which reduces consumption and ambient noise . Over the course of a season, the ZU1 advantageously replaces a window air conditioner and relieves the burden on existing electric convectors.
AirGreen Operating Tips for a Stairwell
To get 100% of the potential of a wall-mounted heat pump in a stairwell:
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Smart setpoint. Aim for 21°C to 22°C in winter. Avoid alternating between complete stops and large-scale restarts; constant modulation is more economical.
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Interior doors. Leave doors ajar during busy hours to facilitate air circulation between levels.
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Fins. In winter, a slightly upward angle; in summer, horizontal . Automatic sweeping should be slow for heating, medium to fast for cooling.
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Filtration. Clean filters every 6 to 8 weeks (more often if pets or dust are present).
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Exterior clearances. Ensure clearances around the condenser (snow and vegetation), especially on the discharge side.
Grants and Compliance: What You Need to Know in Montreal, Laval, Longueuil, North Shore and South Shore
High-efficiency R-32 wall-mounted heat pumps are often eligible for Quebec's support programs when they meet the required performance thresholds and cover a significant portion of your heating needs. Our team handles:
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Check the eligibility of the Sharp ZU1 indoor unit/condenser pair;
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Provide proof of installation and necessary settings ;
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Advise on heating strategy to maximize real savings and the value of aid .
We support our clients throughout Greater Montreal — Montreal , Laval , Longueuil , North Shore and South Shore — to make the administrative side simple and quick .
What distinguishes an AirGreen installation
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Correct sizing (neither undersized nor oversized) thanks to our thermal balances .
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Quality of fittings : calibrated flares, controlled tightening torque, documented vacuum draw.
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Connection route designed for maintenance (clean access, gentle elbows, UV protection).
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Finishes : harmonized cappings, waterproof seals, identified wiring .
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Service : Annual HVAC check reminder and maintenance offered to preserve the manufacturer's warranty and performance.
Bottom line: a ZU1 that works for two levels, discreetly
This Sharp ZU1 installation in Villeray solves a common problem in Montreal homes: maintaining consistent temperatures between floors without multiplying the number of appliances. By leveraging the geometry of the stairwell and inverter modulation, we deliver four-season comfort with low power consumption—and an aesthetic that respects the spirit of the home.
Whether you are in Montreal , Laval , Longueuil , on the North Shore or the South Shore , our AirGreen team designs HVAC installations that fit your architecture, your uses and your budget. Let's talk about your project: one well-placed head is worth two poorly positioned heads.