Installation of a Sharp BU Multi-Zone heat pump on a flat roof in Rosemont–La Petite-Patrie
Installation of a Sharp BU Multi-Zone R-32 heat pump on a flat roof in Rosemont: performance, silence and cold efficiency, signed AirGreen, HVAC experts in Montreal, Laval and the South Shore.
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 high-rise installation optimized for lasting comfort in the heart of Montreal
At AirGreen , we recently completed a careful installation of a Sharp BU Multi-Zone heat pump on the flat roof of a residential building located in the Rosemont–La Petite-Patrie area. This neighborhood, known for its typical duplexes and triplexes, is ideal for rooftop installations, allowing optimal clearance for air circulation and maximum energy efficiency.
Project background
The client, the owner of a six-unit rental building, wanted to modernize its air conditioning and heating system to reduce energy costs and limit maintenance. Their goal was to provide each unit with an independent, quiet, and energy-efficient solution , while complying with Montreal's roofing installation standards.
After a detailed thermal analysis, our team recommended the Sharp BU Multi-Zone , a wall-mounted R-32 multi-zone heat pump known for its excellent cooling performance (-25°C) and stable operation in dense urban environments.
Technical details of the installation
The installation took place in two phases:
Phase 1: Preparation and structure
Our technicians first reinforced the roof surface using galvanized brackets on treated wooden rails, ensuring even distribution of the condenser's weight.
Each outdoor unit has been mounted on anti-vibration bases to reduce noise and vibrations inside the homes.
Phase 2: Connections and commissioning
The refrigerant lines were carefully routed through the technical ducts to the interior heads, with particular attention paid to protecting the ducts against temperature variations.
Shielded electrical cables were installed in accordance with RBQ standards and the Canadian Electrical Code.
The installation includes:
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2 Sharp BU Multi-Zone outdoor units, each supplying 3 separate zones;
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Support on galvanized rails with anti-corrosion treatment;
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Optimized gravity drainage thanks to the roof slope;
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Complete nitrogen leak test and extended vacuum before charging with R-32.
A performance at the rendezvous
Thanks to Sharp Inverter R-32 technology, the system offers:
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A seasonal efficiency (SEER) greater than 21;
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Reliable heating capacity down to −25°C;
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A noise level below 45 dB , ideal for urban environments;
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Compatibility with energy-saving subsidy programs (Hydro-Québec and Transition Énergétique Québec).
Tenants now enjoy individualized comfort , with independent regulation for each interior zone and precise temperature control using intuitive wall-mounted remote controls.
Constraints and technical solutions
Working on a flat roof in an urban environment requires careful planning.
Our teams had to deal with:
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Restricted access conditions , requiring lifting of equipment using a motorized hoist;
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Optimal cable management to avoid any overload on the waterproofing membrane;
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Reinforced UV and rain protection for hoods and ducts.
Each step was supervised by our RBQ certified team leader, ensuring full compliance with the standards of the Quebec Building Code .
A sustainable and energy-efficient solution
The Sharp BU Multi-Zone heat pump combines performance, efficiency and reliability , while respecting modern environmental imperatives.
Its R-32 refrigerant reduces global warming potential by 68% compared to R-410A, thus fully in line with the energy transition encouraged by the City of Montreal.
Our AirGreen support
At AirGreen, we support our clients every step of the way:
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Personalized energy study ;
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Selection of optimal equipment according to the type of building and budget;
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Professional installation certified RBQ and CCQ ;
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Fast and reliable after-sales service , including annual preventive maintenance.
Our commitment: to offer each customer in Greater Montreal, from Laval to Longueuil, a durable, aesthetic HVAC installation that is perfectly adapted to their environment .
In summary
This installation perfectly illustrates AirGreen's expertise in installing HVAC systems on residential roofs in Montreal. Through rigorous planning, careful execution, and cutting-edge technology, we transformed a simple roof into an invisible source of comfort and energy efficiency .
How it goes, from the first call to the end
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 the unit delivers when it is cold
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 BU 24 0002 Zones (Dual Zone) | 25,000 | 21,200 | −27 °C: 14,600 | 2.3 | 24.0 | 11.5 | $3,000 |
| Sharp BU 24 0003 Zones (Triple Zone) | 25,000 | 21,200 | −27 °C: 14,600 | 2.3 | 24.0 | 11.5 | $3,000 |
Among the year’s most efficient according to ENERGY STAR, on top of its cold-climate certification.
Minimum certified capacity (NEEP): it slows down instead of stopping when a single room calls.
NEEP still lists 14,600 BTU/h at a COP of 1.84 at −17 °F.
Global warming potential of R-32, versus 2,088 for R-410A (ENERGY STAR).
Among the year’s most efficient according to ENERGY STAR, on top of its cold-climate certification.
Minimum certified capacity (NEEP): it slows down instead of stopping when a single room calls.
NEEP still lists 14,600 BTU/h at a COP of 1.84 at −17 °F.
Global warming potential of R-32, versus 2,088 for R-410A (ENERGY STAR).
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.
And 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.
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.
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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?
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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).