Installation of a GREE FreeMatch R32 GWHD(24)ND6MO two-head wall-mounted heat pump in Saint-Roch-de-Richelieu
No ground space for the outdoor unit: we installed a GREE FreeMatch R32 2-head heat pump on the roof, on a raised aluminum support. Load calculation, brazing under nitrogen, evacuation to 500 microns—the project explained in detail.
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 shingle roof, two zones to cool, and a compressor that had to withstand the Richelieu winter
This Saint-Roch-de-Richelieu project did not resemble typical residential installations on the South Shore. The client, who owned a low-slope-roof home adjoining a section with vinyl siding, had no viable ground location for the outdoor unit: a side easement that was too narrow on one side, mature landscaping on the other, and a bedroom window less than two metres from the only remaining clearance. At AirGreen, we proposed a solution that few contractors are willing to take on: installing the compressor on the roof, on an elevated aluminum structure resting on treated-wood sleepers, itself supported by a protective membrane.
The result is visible in the project photos: a GREE FreeMatch R32 wall-mounted heat pump, with two heads, powered by a GWHD(24)ND6MO compressor, evacuated and tested on-site before startup.
Why FreeMatch R32 for this home
The system choice was anything but arbitrary. Two zones to condition, a need for heating down to -30°C, and severe outdoor space constraints: the specifications pointed directly to a multi-zone system with a single compressor.
Technical data for the GWHD(24)ND6MO
| Parameter | Value |
|---|---|
| Rated cooling capacity | 24,000 BTU/h (7,030 W) |
| Cooling modulation range | 7,500–31,400 BTU/h |
| Rated heating capacity | 24,000 BTU/h |
| Heating modulation range | 7,500–31,400 BTU/h |
| SEER2 | 21 |
| HSPF2 | 10 |
| EER2 | 12 |
| COP | 3,9 |
| Connectable indoor units | 2 to 3 |
| Power supply | 208/230 V |
| MCA / MOCP | 19.5 A / 25 A |
| Refrigerant | R32, 60 oz (1,700 g) precharge |
| Precharged piping length | 98 ft (30 m) |
| Maximum total length | 197 ft (60 m) |
| Maximum height difference | 49 ft (15 m) |
| Heating range | -30°C to 24°C |
| Cooling range | -30°C to 48°C |
| Sound level (high speed) | 58 dB(A) |
| Net weight | 112.5 lb (51 kg) |
| Certifications | ENERGY STAR, AHRI, ENERGY STAR Cold Climate |
| Warranty | 10-year compressor and parts warranty (+2 years with registration) |
The decisive factor here is the modulation range: 7,500 to 31,400 BTU/h. A fixed-speed 24,000 BTU system would have cycled continuously during the shoulder seasons in a house of this size. The FreeMatch’s G10 inverter technology allows the compressor to operate below one-third of its rated capacity and maintain the temperature without the fluctuations that undermine comfort—and the compressor’s service life.
Second point: the allowable 15 m height difference. On a rooftop installation with indoor units located one floor below, this allowance is not a theoretical luxury; it determines oil return to the compressor. We verified the calculation before even ordering the equipment.
The actual course of the installation
Day 1 — Assessment and load calculation
We never size a heat pump by square footage. A simplified Manual J–style assessment was carried out: facade orientation, window area and type, wall insulation level, estimated air infiltration, and above all the actual use of the rooms. This step ruled out both an 18,000 BTU system (insufficient for the main open-plan area) and a 36,000 BTU system (oversized, and therefore poor at summer dehumidification).
Day 2 — Structure and outdoor-unit positioning
A rooftop installation imposes requirements that a ground-level installation does not:
- Load distribution: the 51 kg compressor cannot rest on two points. We used treated-wood sleepers placed on a protective membrane, distributing the load across several rafters rather than a single one.
- Elevated aluminum stand: the frame raises the unit above the roof surface. This clearance is essential for draining defrost water in winter and preventing accumulated snow from obstructing the coil.
- Anti-vibration strapping: the unit is secured to the wall structure with straps, a detail visible in the photo. On a roof, transmitting vibrations through the framing is the main source of customer complaints. We systematically anticipate it.
- Condensate recovery pan: visible on the ground in the image before installation. In heating mode, defrosting produces water. Without a pan or a directed drain, this water freezes on the shingle and destroys the membrane within three winters.
Day 3 — Refrigerant lines, brazing, and evacuation
The 1/4 in. (liquid) and 3/8 in. (gas) lines were insulated and routed along the siding, with a downward path toward the indoor heads. Two points on which we do not compromise:
- Nitrogen brazing. Any soldering performed without a nitrogen purge leaves copper oxides inside the line. These particles migrate, clog the expansion valve, and kill the compressor—often after the competitor’s labor warranty has ended.
- Evacuation to 500 microns with a standing vacuum test. In the photo, the manifold gauge set is connected to the service ports. Evacuation is not a three-minute formality: we pull down to the target, isolate the system, and observe the rise. A rapid rise indicates residual moisture or a leak. With R32, whose operating pressures are higher than those of R410A, this rigor is non-negotiable.
The compressor’s third port (identified as GAS C on the chassis) was left capped and sealed. This is a tangible benefit for the customer: adding a third head in the basement remains possible without replacing the compressor.
Day 4 — Electrical connection and commissioning
Dedicated 208/230 V power supply, 25 A protection in accordance with the technical data sheet’s MOCP, an accessible outdoor disconnect, and verified grounding. Commissioning includes checking superheat and subcooling, verifying the integrated self-diagnostic system, and providing the customer with a complete demonstration—controls, night mode, and filter cleaning.
The mistakes we see most often on multi-zone installations
We regularly take over improperly installed systems in Montreal, Laval, Longueuil, and along the North Shore. The defects recur with striking consistency:
- Unadjusted refrigerant charge. The GWHD(24) is precharged for 30 m of piping. Beyond that, you must add 0.2 oz/ft (20 g/m). An installer who skips this step on a 40 m run delivers an undercharged system that will never achieve its advertised SEER2.
- Oversized indoor units for the rooms. On a multi-zone system, the combined capacities of the indoor units can exceed that of the compressor—this is normal and expected. What is not normal is a 12,000 BTU indoor unit in a 100 sq. ft. bedroom. It will short-cycle, circulate cold, un dehumidified air, and the client will sleep poorly.
- Indoor condensate drain running uphill. The gravity drain must have a continuous slope. A 5 mm low spot is enough to create a biological blockage and a leak through the wall in the middle of a heat wave.
- No protection for the outdoor coil. On an exposed installation like this one, the coil is protected by a mesh guard against debris and hail.
Eligibility for financial assistance
The GWHD(24)ND6MO is ENERGY STAR certified and bears the ENERGY STAR Cold Climate designation, with an HSPF2 of 10 and a SEER2 of 21. These specifications place the unit in the categories generally covered by energy-efficiency programs available in Quebec, including Hydro-Quebec's LogisVert program. The criteria, amounts, and eligibility conditions change from year to year: we systematically verify the application with the client before signing, and we provide the required technical documentation and proof of installation. We never promise an amount without verifying it beforehand—that is a frequent source of disappointment in our industry.
What this project illustrates about our approach
A rooftop installation is not a fallback solution. It is a technical choice that requires a structural assessment, serious management of winter condensate, vibration control, and safe access for future HVAC maintenance. We recommended it in Saint-Roch-de-Richelieu because it gave the client a unit away from their bedroom window, protected from snow removal, and fully accessible for servicing.
AirGreen serves Montreal, Laval, Longueuil, the North Shore, and the South Shore, including the Richelieu Valley. We perform load calculations, supply, complete HVAC installation, electrical connection, documented commissioning, and annual maintenance of your wall-mounted heat pump.
For an evaluation of your project or a detailed quote, contact our team.
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.
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.
More jobs to see, near you
By town, by equipment or by region: browse more than 4,700 published projects.
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).