Installation of a Sharp (ZU1 series) wall-mounted heat pump in Saint-Laurent – condenser on flat roof
Sharp ZU1 series wall-mounted heat pump installed by AirGreen in Saint-Laurent . Flat roof condenser with H-stands, UV cladding and controlled drainage for four-season comfort. HVAC service in Montreal, Laval, Longueuil, South Shore and North Shore.
Take a tour of the installation
Each number is a point we check on site. Switch between summer and winter to watch air and heat move.
In summer, the outdoor unit rejects the house's heat outside.
Generic illustration of this type of installation, not a survey of this job site. Tap a number.
Mounted level on a wall plate, high enough for the air to reach the whole room, with enough space around it to slide the filters out easily.
The refrigerant lines, the communication cable and the drain go through the wall in a single opening, sealed against water, cold air and insects.
Two insulated copper pipes connect the two units. Outside, a line cover can protect them from sun, knocks and weather.
A shut-off switch near the outdoor unit isolates it safely for service. It must stay accessible at all times.
The compressor and the fan. In heating mode it captures heat from the outdoor air, even in winter, and moves it inside.
On the ground or on the wall, it keeps the unit above accumulated snow. The unit stays clear and defrost water can drain away.
The fan needs to blow freely. Storage, a fence or a wall too close, and efficiency drops while noise goes up.
A rooftop installation designed for Montreal's climate, by the AirGreen team
At AirGreen , we carried out a complete HVAC installation in a flat-roofed building in the Saint-Laurent district (Montreal): a Sharp ZU1 series wall-mounted heat pump with a condenser installed on the roof on raised supports. The client's objective was twofold: to benefit from four-season comfort for a large open-plan space, while preserving the aesthetics of the facades and freeing up the ground floor . The site presented a typical challenge for urban roofs: stagnant water after rain and numerous existing holes (ventilation, vents). We designed a robust, durable solution that complied with local standards, designed for Montreal winters and intense rain events.
Building context and implementation strategy
The building is a low-rise building surrounded by greenery and other technical roofs. The presence of water reflections on the membrane confirmed a temporary retention typical of bituminous/gravel roofs. In this context, we favored:
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Raising the condenser on anti-vibration H-stands , height calculated to stand above potential puddles and the winter snow line .
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Compact refrigerated path , protected by UV capping up to a waterproof roof passage (“gooseneck” cap and flashing).
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Dedicated electrical section with roof disconnect , UV-resistant reinforced wiring and secure routing.
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Condensate management : roof discharge with positive slope towards an evacuation point; heating cable option provided if the customer decides to operate in air conditioning mode at temperatures close to 0°C.
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Wind protection : orientation of the condenser with its back to the prevailing gusts on the site, clearances respected for optimal air flow and to avoid recirculation.
Inside, the Sharp wall-mounted unit is positioned high to take advantage of the Coanda effect and efficiently cover the work area. This configuration reduces on/off cycles and stabilizes the temperature, especially during afternoon heat waves .
Key steps in AirGreen installation
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Load study and electrical verification (circuit breaker, wire gauge, grounding).
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Structural identification : routing of lines without interfering with existing conduits or reinforcing steel; location of the drilling area with safety margin.
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Drilling and roof passage : collar + flashing, butyl mastic and polyurethane sealant; tar pocket avoided in favor of a modern mechanical assembly.
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Condenser mounting : H-stands placed on distribution pads (membrane protection), level checked; silent blocks to limit vibration transmission to the building.
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Copper lines : dynamometer flares, bending radii respected; class 1 UV-resistant insulation, taped joints and continuous cover .
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Nitrogen test (pressurization and bubble test), then deep vacuum drawing up to the validated micron threshold; vacuum holding checked.
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Commissioning : opening of valves, reading of currents, reference superheating/subcooling , indoor air flow test, calibration of gravity drain .
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Finishing touches : disconnect signaling, interior/exterior sealing , area cleaning, compliance photos for the customer file.
Why the Sharp ZU1 series for Saint-Laurent?
The Sharp ZU1 ( R-32 refrigerant) is a wall-mounted heat pump designed for extreme cold and urban buildings :
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High-precision inverter compressor : fine modulation, energy savings and reduced wear.
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High efficiencies (SEER/HSPF) and reliable low temperature heating , relevant for Montreal.
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Controlled acoustics : a major advantage on a flat roof close to other occupants.
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Simplified maintenance : direct access to the condenser, easy-to-remove panels, protected electronics.
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R-32 : lower charge and better volumetric efficiency compared to older fluids.
For this space, the 12,000–18,000 BTU range meets the needs after sizing (volumes, solar gains, envelope). The solution remains scalable if a future multi-zone proves relevant.
“Flat roof” specificities: what we put in place
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Water management : the slight stagnation visible after rain does not affect operation; the H-stands ensure ground clearance. We check the roof slope and the position of the drains to avoid any prolonged immersion of the supports.
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Snow clearances : the free height under the unit facilitates defrosting and limits snow banks around the fan.
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Anti-corrosion : galvanized/stainless steel hardware, protected anchor points, UV-resistant conduits and insulation.
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Noise/Vibration : flow direction and silent blocks to avoid transmitting vibrations to the occupants; sound control in forced operation.
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Safety & Access : Clear access path, disconnect within reach, clear labeling for future maintenance.
HVAC Use and Maintenance Tips
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Winter : stable setting (20–21°C), cleaning filters every 1–2 months; check that snow clearances on the roof remain clear.
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Summer : dehumidification mode on humid days; setpoint 23–24°C for a good comfort/economy compromise.
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Annual (by AirGreen): electrical inspection, pressure meter checks, exchanger cleaning, condensate drainage test, roof leak tightness check around the roof passage.
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Good to know : avoid forcing setpoint deviations too frequently; the Inverter works better on gentle slopes.
Grants, Compliance and Guarantees
High-efficiency wall-mounted heat pumps like the Sharp ZU1 are generally eligible for incentive programs in Quebec, subject to performance and configuration conditions. We support:
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eligibility verification ,
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preparation of the file (serial numbers, detailed invoices, before/after photos),
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submission and monitoring, in order to optimize return on investment .
The installation complies with RBQ and CSA standards, as well as the requirements of the co-owner /owner for any roofing work (access, PPE, schedules). Our work is covered by a clear labor warranty ; maintenance plans are offered to maintain the performance and longevity of the equipment.
Result: stable performance, contained noise, preserved roof
Upon commissioning, the treated room quickly reaches the setpoint ; the condenser switches to low speed with a discreet noise level, without resonance in the structure. The raised installation and the covered route protect the installation from hazards (rainwater, snow, UV), while facilitating access for future maintenance . The customer benefits from measurable comfort , improved air quality and a reduction in the energy bill compared to direct electric heating or a non-Inverter air conditioner.
AirGreen, your HVAC partner in Greater Montreal
We provide custom solutions for flat roofs, houses, plexes and condos in Montreal, Laval, Longueuil, on the South Shore and the North Shore . Our teams install and maintain wall-mounted heat pumps (Sharp, Gree , Midea , Fujitsu ), central systems and interior systems (cassette, ducted, console). Each project is delivered clean, compliant and documented .
The unit on this job, in figures
The range as published on airgreen.ca: pick a size to see its capacity in deep cold.
| Size | Heating at −8 °C | Heating at −15 °C | Coldest certified point | COP at −15 °C | SEER | HSPF | Indicative LogisVert aid |
|---|---|---|---|---|---|---|---|
| Sharp ZU1 12 000 | 14,500 | 12,000 | −27 °C: 7,200 | 2.11 | 22.0 | 11.0 | $1,740 |
| Sharp ZU1 15 000 | 18,100 | 15,300 | −27 °C: 10,100 | 2.1 | 24.0 | 11.0 | $2,172 |
| Sharp ZU1 18 000 | 22,000 | 18,000 | −27 °C: 11,500 | 2.2 | 24.0 | 11.0 | $2,640 |
| Sharp ZU1 24 000 | 22,400 | 19,000 | −27 °C: 12,300 | 2.2 | 22.0 | 11.0 | $2,688 |
According to NEEP, it delivers 14,500 BTU/h at −8 °C (17 °F), more than at 8 °C (14,000 BTU/h). It heats as hard in moderate cold as in mild weather.
According to NEEP, its certified maximum capacity at −27 °C (−17 °F) is 7,200 BTU/h, 60% of its nominal 12,000 BTU size.
At 8 °C, its certified maximum capacity reaches 17,100 BTU/h, 42% more than its nominal 12,000 BTU size.
According to NEEP, it delivers 18,100 BTU/h at −8 °C (17 °F), more than at 8 °C (18,000 BTU/h). It heats as hard in moderate cold as in mild weather.
According to NEEP, its certified maximum capacity at −27 °C (−17 °F) is 10,100 BTU/h, 67% of its nominal 15,000 BTU size.
At 8 °C, its certified maximum capacity reaches 21,800 BTU/h, 45% more than its nominal 15,000 BTU size.
According to NEEP, it delivers 22,000 BTU/h at −8 °C (17 °F), more than at 8 °C (21,600 BTU/h). It heats as hard in moderate cold as in mild weather.
According to NEEP, its COP at −27 °C is 1.88: the highest of the ZU1 line, which ranges from 1.79 to 1.82 at that temperature.
According to NEEP, its certified maximum capacity at −27 °C (−17 °F) is 11,500 BTU/h, 64% of its nominal 18,000 BTU size.
At −27 °C, its certified minimum capacity is 3,200 BTU/h (5,500 at 8 °C). It slows down instead of cycling on and off.
According to NEEP, its certified heating capacity at −15 °C (5 °F) is 19,000 BTU/h, 79% of its nominal 24,000 BTU size. Its COP there is 2.20.
Data read live from the airgreen.ca page of each size (NEEP / AHRI certified performance). When the title names the installed size, it is highlighted; otherwise the whole range is shown. The aid shown is today’s, using Hydro-Québec’s rule ($120 per 1,000 BTU/h at −8 °C); amounts quoted in the article date from its publication. Only Hydro-Québec confirms the assistance granted.
The big day, step by step
The main steps of this kind of job at AirGreen. Every house has its quirks: the estimate brings them out.
We look at the room, the outside wall, the line route and where the outdoor unit will go. That is where the capacity gets chosen.
Model, capacity and price, in writing. We also check whether the model qualifies for assistance programs.
Floors and furniture protected, wall plate position marked level, wall opening located.
A single opening, with the slope the drain needs to flow outside.
Set on a stand raised above the snow, with the clearances the manufacturer requires.
Connected, insulated and protected. The opening is then sealed against water, cold air and insects.
A dedicated circuit and an accessible disconnect near the outdoor unit.
Leak test, vacuum, then start-up and a check of heating and cooling.
Remote, modes, filters: we show you the essentials before we leave.
- The on-site estimateWe look at the room, the outside wall, the line route and where the outdoor unit will go. That is where the capacity gets chosen.
- The quoteModel, capacity and price, in writing. We also check whether the model qualifies for assistance programs.
- Getting readyFloors and furniture protected, wall plate position marked level, wall opening located.
- The wall openingA single opening, with the slope the drain needs to flow outside.
- The outdoor unitSet on a stand raised above the snow, with the clearances the manufacturer requires.
- Lines, cable and drainConnected, insulated and protected. The opening is then sealed against water, cold air and insects.
- The electrical workA dedicated circuit and an accessible disconnect near the outdoor unit.
- Tests and start-upLeak test, vacuum, then start-up and a check of heating and cooling.
- The walkthroughRemote, modes, filters: we show you the essentials before we leave.
What would it look like at your place?
Two quick checks with real numbers: what heat costs, and what your current heaters add up to in BTU/h.
Baseboards and electric furnaces turn 1 kWh of electricity into 1 kWh of heat. A heat pump delivers more: that is its COP. At Hydro-Québec’s rate D (11.142¢/kWh above 40 kWh a day, since 1 April 2026):
Hydro-Québec: a heat pump can be up to three times more efficient than baseboards for heating in the colder months.
Estimate per kWh of heat, at the chosen temperature, using the certified COP from the product page. Taxes, access charge and backup heat not included.
Conversion: 1 W = 3.412 BTU/h. An indication, not a load calculation: baseboards and furnaces are often stronger than the real need, and they can stay as backup. AirGreen confirms the capacity on site.
Four mistakes we do not make
Flip each card to see what we do instead.
Your own project, step by step
What to do, season by season
Three habits per season for this unit. They take a few minutes and prevent many calls.
- Clean the indoor unit's filters.
- Clear leaves and debris left on the outdoor unit by winter.
- Test cooling before the first hot days.
- Clean the filters more often when the unit runs a lot.
- Keep plants away from the outdoor unit.
- Check that no water drips from the indoor unit.
- Rake the leaves around the outdoor unit.
- Test heating before the first cold days.
- Book periodic maintenance before winter.
- Keep snow away from the stand and the front of the unit.
- Let the unit defrost: it is normal.
- Never hit the ice on the fins; call us if the unit stays iced up.
Is your home ready?
Check what applies at your place. A "no" is not a refusal: it is what we sort out during the estimate.
Four statements: true or false?
It all comes down to details you have just seen.
1. In heating mode, the outdoor unit can produce water.
During defrost cycles. That water must drain away without forming ice.
2. You pick the capacity with a simple square-footage rule.
Windows, insulation, orientation and how the room is used all count. Capacity is chosen on site.
3. A multi-zone connects several indoor heads to a single condenser.
One head per room, all on the same condenser. Each room keeps its own temperature.
4. The disconnect can sit behind the patio furniture.
It must stay accessible: it is what shuts the unit off for service.
0 / 4 right answers
What people ask us about this kind of work
Does a wall-mounted heat pump heat in winter?
Wall-mounted or multi-zone: how do I choose?
Where does the outdoor unit go?
Are there grants?
Do I need a permit?
How cold can it heat?
How much can I save?
How is the LogisVert assistance calculated?
Is it noisy?
The outdoor unit is covered in ice: is that normal?
Does AirGreen hold the required licences?
Is the estimate free?
No question matches. Write to us: we answer.
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Each dot: a town where AirGreen has published projects. The glowing dot: this job.
Every house has its constraints. We see them before we install.
The on-site estimate is free and the quote follows within 24 hours.
Text and photo: a real AirGreen Climatisation & Chauffage job. The diagrams are generic illustrations of the type of installation, not a survey of this job site. Sources of the added figures: airgreen.ca product pages (NEEP / AHRI performance), Hydro-Québec (Heat pumps page, LogisVert, read on 13 October 2026), Régie de l’énergie (rate D as of 1 April 2026).