Installation of a Midea EVOX G3 central heat pump on a flat roof in Saint-Laurent
Installation of a Midea EVOX G3 central heat pump on a flat roof in Saint-Laurent by AirGreen. A sustainable, efficient HVAC solution perfectly suited to Quebec's climate.
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.
A neat and efficient installation for optimal comfort, even on a flat roof
At AirGreen , we recently completed a complete installation of a Midea EVOX G3 central heat pump in the Saint-Laurent area of Montreal. This project perfectly illustrates our expertise in rooftop HVAC installation, where technical precision and structural durability play a key role in ensuring maximum performance and long-term reliability.
A central heat pump designed for the Quebec climate
The Midea EVOX G3 is a new generation central heat pump operating on R-454B refrigerant , designed to offer stable performance down to -30 °C . This model, with a capacity varying between 2 and 5 tons , is recognized for its superior energy efficiency and its compatibility with modern electric heating systems.
Its inverter compressor continuously adjusts power, allowing for reduced energy consumption and constant thermal comfort in all areas of the home.
Installation details: stability, safety and precision
The outdoor unit was installed on a flat roof , an environment requiring meticulous planning. Here are the main technical elements of the installation:
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Galvanized steel raised stand : designed to provide excellent mechanical stability while allowing good air circulation around the unit.
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Fixing on treated wooden sleepers and insulating base : these elements prevent any vibration transmission to the building structure and prevent moisture infiltration.
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Electrical connection protected via a waterproof box and external circuit breaker, complying with CSA and RBQ electrical standards.
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Optimized gravity drainage thanks to a slight inclination of the support, avoiding any accumulation of water under the unit, essential for cold seasons.
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Protected and insulated refrigeration duct routing , with a short and direct route to minimize heat loss.
All assembly was carried out in the evening, in order to respect the operating hours of the commercial building and limit service interruptions.
A sustainable and energy-efficient choice
The Midea EVOX G3 stands out for its intelligent control system that automatically adapts the fan and compressor speed according to actual thermal needs.
Thanks to its R-454B technology , this heat pump significantly reduces environmental impact, offering a carbon footprint up to 78% lower than systems using R-410A.
In addition, it is eligible for several grant programs in Quebec, including those linked to Transition Énergétique Québec (TEQ) for high energy efficiency appliances.
Challenges encountered and solutions provided
Installing a central heat pump on a flat roof involves several technical constraints:
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Equipment weight and structural strength of the roof : a preliminary check of the permissible load was carried out before installing the support.
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Electrical safety and compliance : The wiring has been secured in a rigid metal conduit with waterproof connectors.
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Weather Protection : Sufficient space has been provided to allow snow runoff and prevent areas of ice accumulation around the unit.
These precautions ensure system longevity, reduce maintenance requirements and ensure stable performance throughout the year.
The result: efficiency, silence and comfort
After commissioning, pressure and temperature tests confirmed optimal performance , with a coefficient of performance (COP) greater than 4.5 in heating mode .
The unit operates quietly , thanks to its rotary compressor and integrated sound insulation. Occupants now enjoy constant comfort, without temperature fluctuations, even on the coldest nights.
Why trust AirGreen for your HVAC projects in Montreal?
At AirGreen, every installation is planned, validated, and executed according to the highest HVAC industry standards . Our RBQ-certified team, partnered with leading brands (Midea, Gree, Fujitsu, Sharp, Zephyr, etc.), ensures:
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Complete expertise , from choosing the model to commissioning;
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Installations that comply with Quebec electrical and mechanical standards ;
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Customized solutions for each type of building;
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Reliable and transparent after-sales service .
We serve all of Greater Montreal , including Laval, Longueuil, the North Shore and the South Shore , and we make it a point of honor to offer aesthetic, secure and efficient installations .
Conclusion: an exemplary project in Saint-Laurent
This Midea EVOX G3 central heat pump installation in Saint-Laurent illustrates the quality of AirGreen work: a perfect balance between energy efficiency, technical precision and compliance with HVAC standards .
Thanks to this system, the building now benefits from superior comfort and significant energy savings—a sustainable, reliable solution adapted to Quebec's harsh winters.
AirGreen – Heat pumps, air conditioning and heating in Montreal, Laval, Longueuil, North Shore and South Shore.
Sustainable facilities. Guaranteed comfort.
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 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 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 |
|---|---|---|---|---|---|---|---|
| Midea EVOX G3 · 1.5 tons | 14,700 | 18,600 | −30 °C: 11,800 | 2.12 | 19.0 | 10.1 | $1,764 |
| Midea EVOX G3 · 2 tons | 20,800 | 20,600 | −30 °C: 12,100 | 2.14 | 18.6 | 10.0 | $2,496 |
| Midea EVOX G3 · 2.5 tons | 24,000 | 33,200 | −30 °C: 17,900 | 1.97 | 17.2 | 10.8 | $2,880 |
| Midea EVOX G3 · 3 tons | 33,000 | 37,400 | −30 °C: 27,600 | 1.9 | 18.0 | 10.0 | $3,960 |
| Midea EVOX G3 · 4 tons | 39,500 | 48,000 | −30 °C: 27,200 | 2.0 | 17.5 | 9.5 | $4,740 |
| Midea EVOX G3 · 5 tons | 45,000 | 54,000 | −30 °C: 37,300 | 1.9 | 17.5 | 9.5 | $5,400 |
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.
- 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.
Which type of equipment for your project?
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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?
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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).