Installation of a Gree Flexx R32 central heat pump in Saint-Laurent
AirGreen installed a Gree Flexx R32 central heat pump on a flat roof in Saint-Laurent . An exemplary achievement in terms of energy efficiency and comfort, adapted to the Montreal climate.
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The job on one screen
The article, chapter by chapter
A flat roof installation in the heart of the Saint-Laurent industrial sector
In the dynamic landscape of Saint-Laurent, between modernized warehouses and mixed-use buildings, AirGreen recently completed a Gree Flexx R32 central heat pump installation , specially adapted to the constraints of a commercial flat roof .
This project perfectly illustrates our expertise in efficient and sustainable HVAC (heating, ventilation and air conditioning) systems for the Montreal climate.
A strategic choice: the Gree Flexx R32
The Gree Flexx R32 stands out as one of the most modern central solutions in its class. Designed to deliver stable performance down to -25°C , this central heat pump combines power, energy efficiency and reliability.
Its variable-speed compressor and R-32 refrigerant make it both environmentally friendly and efficient—ideal for high-occupancy or mixed-use buildings.
Key features of the Gree Flexx R32:
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Capacities from 2 to 5 tonnes , perfect for multi-unit buildings and businesses.
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Operates on R-32 , reducing global warming potential by 68% compared to R-410A.
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High-efficiency inverter compressor for better power modulation.
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Reduced noise level , essential for installations in dense urban environments.
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Compatibility with Quebec subsidy programs (Hydro-Québec, LogisVert, etc.).
The challenges of a flat roof: stability, drainage and safety
Installing a heat pump on a flat roof requires careful planning. In this project, our team considered several technical parameters:
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Anti-vibration support mounted on sturdy metal rails, ensuring the stability of the unit despite thermal variations and high winds.
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Drainage management by gentle slope, avoiding any stagnation of water under the structure.
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Protected routing of refrigerant pipes and electrical wiring through existing service ducts.
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Respect for the white waterproofing membrane , crucial for the durability of the roof.
Thanks to our experience in HVAC installation on flat roofs , each step was carried out with rigor — from precise positioning of the unit to complete commissioning.
Integration into existing system
The building already had an air duct network, which allowed efficient integration of the Gree Flexx R32 into the existing central system.
Our technicians adjusted the connections and checked the air balance to ensure uniform comfort across all zones .
This approach avoids pressure drops and optimizes energy consumption, an essential asset for owners looking to reduce their operating costs .
Performance and efficiency: everyday comfort
Since its start-up, the Gree Flexx R32 system has maintained stable comfort conditions, both in summer and winter.
In heating mode, it uses the heat from the outside air even at -25°C; in air conditioning mode, it guarantees a constant indoor temperature, while effectively filtering the air circulating in the ducts.
Results obtained:
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Optimal thermal comfort throughout the building.
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Estimated average reduction of 25% on annual energy bill .
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Simplified maintenance thanks to secure technical access to the roof.
Why choose AirGreen for your flat roof installations?
At AirGreen , we have developed specific expertise in the installation of central heat pumps on flat roofs and commercial buildings .
Our facilities meet the highest standards of safety and performance, while integrating sustainable ecological solutions.
Our commitments:
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Free on-site evaluation before any submission.
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Transparent and detailed prices , no surprises.
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Full installation warranty , compliant with manufacturer requirements and RBQ standards.
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Responsive after-sales service covering all of Greater Montreal , from Laval to the South Shore .
An exemplary project for sustainability and energy efficiency
This Saint-Laurent project demonstrates how modern HVAC technologies can adapt to urban architecture while meeting the energy requirements of today's Quebec.
The combination of a new generation refrigerant , careful installation and AirGreen know-how makes all the difference.
Are you planning a similar project?
Contact our team for a personalized assessment of your HVAC needs.
Whether for a residential, commercial or industrial building , our experts will be able to recommend the most efficient and cost-effective solution , supported by available subsidies.
The job tools
Two quick checks with real numbers: what heat costs, and what your current heaters add up to in BTU/h.
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.
How the job unfolds
The main steps of this kind of job at AirGreen. Every house has its quirks: the estimate brings them out.
We look at the ducts, the current indoor module, the electrical panel and the planned spot for the outdoor unit.
The equipment combination, capacity and price, in writing. We check whether the combination qualifies for assistance programs.
Access protected, old unit disconnected and removed when it is being replaced.
Electric furnace or air handler, with its coil, connected to the supply and return ducts.
On a level base, raised above the snow, with free space all around.
Insulated, they enter through a sealed opening and run to the indoor coil.
Dedicated circuits, accessible disconnect, a thermostat that works with the heat pump and the backup heat.
Leak test, vacuum, start-up, airflow check and a test of both modes.
Filter, thermostat, backup heat in extreme cold: what to know before winter.
- The on-site estimateWe look at the ducts, the current indoor module, the electrical panel and the planned spot for the outdoor unit.
- The quoteThe equipment combination, capacity and price, in writing. We check whether the combination qualifies for assistance programs.
- Getting readyAccess protected, old unit disconnected and removed when it is being replaced.
- The indoor moduleElectric furnace or air handler, with its coil, connected to the supply and return ducts.
- The outdoor unitOn a level base, raised above the snow, with free space all around.
- The refrigerant linesInsulated, they enter through a sealed opening and run to the indoor coil.
- Electrical and thermostatDedicated circuits, accessible disconnect, a thermostat that works with the heat pump and the backup heat.
- Tests and start-upLeak test, vacuum, start-up, airflow check and a test of both modes.
- The walkthroughFilter, thermostat, backup heat in extreme cold: what to know before winter.
What we check on a job like this one
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.
It captures or rejects heat outside. It sits on a level base, above the snow, with free space all around.
The insulated refrigerant lines enter the house through a sealed opening and run to the indoor coil.
A shut-off switch near the outdoor unit isolates it safely for service.
Sitting on the indoor module, it moves heat between the house air and the refrigerant.
Electric furnace or air handler: its fan pushes air through the ducts. The electric backup takes over in extreme cold.
Supply ducts bring air to the rooms; returns bring it back to the unit. Their condition matters as much as the unit's.
It protects the coil and the fan. A dirty filter cuts airflow, so it gets checked regularly.
It runs the heat pump and the backup heat. It must be compatible with the installed system.
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.
Good habits, once the unit is in place
Six simple habits that keep the unit going. Your list stays on this device.
What to do, season by season
Three habits per season for this unit. They take a few minutes and prevent many calls.
- Check the indoor module's filter.
- Clear winter debris from the outdoor unit.
- Test cooling before the heat arrives.
- Check the filter more often in peak season.
- Keep registers and returns clear.
- Watch condensate drainage near the coil.
- Change or clean the filter.
- Test heating and backup heat before the cold.
- Book periodic maintenance.
- Clear snow around the outdoor unit.
- Store nothing in front of the indoor module.
- Note any unusual noise or smell and call us.
The right pages, at the right time
Four statements: true or false?
It all comes down to details you have just seen.
1. A central heat pump uses the house's ducts.
It connects to the existing ducts to heat and cool everywhere.
2. In extreme cold, electric backup heat can take over.
The indoor module (furnace or air handler) works with the heat pump and takes over in extreme cold.
3. The filter only gets changed when the unit breaks down.
A dirty filter cuts airflow. It gets checked regularly.
4. You can reuse the old unit's size without checking.
The house may have changed: insulation, windows, added rooms. Capacity is confirmed on site.
0 / 4 right answers
What people ask us about this kind of work
Can I keep my current ducts?
What happens in extreme cold?
Furnace, air handler, ducted: what is the difference?
Are there grants?
Do I need a permit?
How much can I save?
How is the LogisVert assistance calculated?
Will my current thermostat work?
Central or wall units: which one?
Does AirGreen hold the required licences?
Is the estimate free?
No question matches. Write to us: we answer.
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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).