Installation of a GREE FreeMatch R32 two-head heat pump in Sainte-Anne-de-Bellevue, at the western tip of the Island of Montreal

The A2L leak detection sensor: the standard component no quote mentions

On the side of the outdoor unit we have just commissioned in Sainte-Anne-de-Bellevue, two labels catch the eye: the flame pictogram accompanied by the A2L R32 marking, and the bilingual warning about electrical hazards. Most homeowners never notice them. Most quotes never mention them either. Yet these labels sum up a real change in the way a wall-mounted heat pump is installed in 2026, and they explain some of the decisions we made on this specific project: a village home with red siding, a few streets from the canal, equipped with a GREE FreeMatch R32 2-zone heat pump using a GWHD(24)ND6MO compressor.

At AirGreen, we install HVAC systems throughout Montreal, Laval, Longueuil, the North Shore, and the South Shore, and the West Island is taking up an increasingly larger share of our schedule: Baie-D'Urfé, Beaconsfield, Kirkland, Pointe-Claire, Dollard-des-Ormeaux, L'Île-Bizard. Sainte-Anne-de-Bellevue, at the far end of the island, naturally completes this list—and this project gave us the opportunity to address two topics we had never put in writing before: the exact role of the A2L leak detection sensor supplied as standard with this line, and what happens to the refrigerant lines once they emerge from the wall.

R32, without the jargon: what the A2L class means

R32 refrigerant is gradually replacing R410A in residential product lines, for one simple reason: its global warming potential is approximately three times lower, while the amount of gas per unit is generally smaller. The trade-off is its A2L classification: low toxicity, but slight flammability under very specific concentration conditions. Standards governing A2L equipment therefore impose requirements that older-generation refrigerants did not: visible labels on the casing, minimum room areas for each indoor unit, and—on the FreeMatch R32 line—an factory-installed leak detection sensor.

We have already published the relevant nameplate values (minimum installation height, minimum room size) in our article about an installation in Dundee, and the principle that the smallest room governs the entire circuit in the one about Varennes. We will not revisit them here. What interests us in Sainte-Anne-de-Bellevue is the sensor itself.

What the sensor does—and what it does not replace

The sensor's role is easy to summarize: detect an abnormal refrigerant concentration and trigger the response specified by the manufacturer, including circulating air to disperse the gas before a significant concentration forms. It is a mitigation device, not a license to do poor work. Three points we systematically explain to our customers:

• The sensor does not replace the calculation. Minimum room sizes remain mandatory, with or without a sensor. Equipment installed in a room that is too small is non-compliant even if it never triggers an alarm.
• The sensor does not replace leak-tightness. The quality of the flares, evacuation below 500 microns maintained and verified, and torque tightening: that is what makes an HVAC installation leak-free. The sensor is the seat belt, not the brake.
• The device's exact behavior depends on the model and the installation manual. We verify it during commissioning, explain it to the customer, and record the verification in the job completion file.

On this job, one element simplified the entire A2L process: the factory charge. The GWHD(24)ND6MO leaves the factory with 1,700 g of R32, precharged for 30 meters of line set. Our two runs—approximately 7 meters to the living room head and 12 meters to the upstairs head—total 19 meters. No refrigerant added, no additional weighing, and a minimum room-size calculation still based on the factory charge documented on the nameplate. When a home's layout allows it, keeping the lines below the precharge threshold is an administrative and technical advantage that few people quantify.

Two heads, three paths to 100%: why 15,000 + 9,000

The compressor is rated at 24,000 BTU/h for both cooling and heating, with a modulation range of 7,500 to 31,400 BTU/h. We have already connected this same model in a 12,000 + 12,000 configuration in Dollard-des-Ormeaux and an 18,000 + 6,000 configuration in Côte-des-Neiges–Notre-Dame-de-Grâce. Sainte-Anne-de-Bellevue introduces the third path to the same total: 15,000 + 9,000 = 24,000 BTU/h, or 100% of the rated capacity.

The arithmetic is identical in all three cases; the house never is. Here, the ground floor forms an open volume—living room, dining room, and kitchen arranged in a row—too large for a 12,000 BTU/h head, while the upper floor consists of a primary bedroom and an office sharing the same landing: a single 9,000 BTU/h head is enough there. A 12 + 12 would have undersized the lower floor and oversized the upper floor; an 18 + 6 would have done the opposite. The distribution is not chosen from a combination chart; it is read from the house plan. That is precisely why the range offers seven head sizes.

The useful figures for the installed model:

The indoor heads are powered by the outdoor unit: a single electrical circuit serves both zones. The outdoor disconnect and the rules surrounding it have their own article, the one about our Rosemont–La Petite-Patrie installation, and the panel load calculation belongs to the master electrician.

Sleeve, tape, or line-hide: what happens to the lines once they are outside

The photo of this job shows what most manufacturer pages hide: the back of the installation. The unit sits on its elevated stand, in a narrow passage between the house wall and the neighboring red wall, and the line set—two pairs of insulated copper lines, two interconnection cables, and the drain—runs vertically through this gap, tied and sleeved, before following the siding to its penetration point. This part of the work neither cools nor heats anything. Yet it determines two things: how long the line insulation will last, and what the façade will look like ten years from now.

Three ways to finish an outdoor line set

There are three finish levels for exposed refrigerant lines, and we present them honestly, with their prices and limitations:

1. Spiral wrap or vinyl tape, applied with tight overlapping wraps from bottom to top so that water runs over the joints and never into them. This is the finish selected in Sainte-Anne-de-Bellevue: the line set runs along a barely visible side wall, in a passage no passerby can see. Light mechanical protection, minimal cost, and easy replacement during maintenance.
2. The rigid raceway (the plastic profile seen on façades), which stiffens the route, can be painted, aligns with the building's lines, and — above all — opens and closes. When a technician needs to inspect a line, a raceway can be unclipped; a taped line set has to be cut open and redone entirely. On a front façade or along a long horizontal run, we recommend it almost every time.
3. No finish, with the foam insulation left bare. We reject this option: UV rays break down the insulation within a few summers, and a poorly insulated suction line loses capacity and develops condensation. We described the UV-resistant covering for long exposed runs in our Dollard-des-Ormeaux article.

The choice is therefore not primarily aesthetic: it depends on sun exposure, visibility, route length, and the likelihood that someone will need to return to it. A good contractor will ask you about this; an estimate that says nothing about it has simply chosen for you, and rarely for the better.

What the narrow passage required

Working in a gap only a few dozen centimeters wide between two walls dictated the work sequence. The line set was covered and tied before the unit was permanently installed, because no tool can fit behind it once the equipment is in place. Each cable enters the electrical compartment through its own knockout opening, with its own cable clamp, while unused openings remain sealed — an outdoor electrical box deteriorates from water, never from cold. Finally, the service clearance on the panel side was measured before anything was secured: equipment that can no longer be opened is equipment that will not be maintained.

The mistakes we see on outdoor line sets

• Tape applied from top to bottom, with joints exposed to the rain: water seeps beneath the covering and saturates the insulation.
• Insulation interrupted where it passes through the wall or near the service valves: localized condensation, drips, and stains on the cladding.
• Beam used as a support — copper must never bear the weight of a cable, garden hose, or snow shovel leaning against it in January.
• Condensate drain buried in the line set without its own slope: it must descend continuously on its own to its discharge point.
• The line cover was chosen for the finished-project photo, but it was screwed in without sealing around the penetrations: a neat finish does not replace watertight sealing around the opening.

Sainte-Anne-de-Bellevue: a village, a campus, two lakes

Installing at the western tip of the island has its own character. Sainte-Anne-de-Bellevue lies between Lake Saint-Louis and the Lake of Two Mountains, around its federal canal and waterfront boardwalk, with McGill University's Macdonald Campus and John Abbott College anchoring village life. The buildings are varied—tightly spaced village homes near the main street and newer properties farther north—and the narrow lots in the village core present exactly the challenge of this project: finding a location for the outdoor unit that complies with clearance requirements, respects the neighbours, and meets municipal regulations all at once. Our website also compiles the regulations applicable to outdoor equipment for municipalities across Greater Montreal; our office team can answer these questions by phone as well.

As for financial assistance, this model is ENERGY STAR certified and cold-climate approved, with its AHRI reference numbers published for ductless, ducted, and mixed configurations—the exact references required for a grant application. Programs applicable to an electrically heated residence, including Hydro-Québec's LogisVert program, change regularly: we verify each project's eligibility when preparing the quote rather than promising amounts on a page that will become outdated.

One honest note to finish: this home's electric baseboard heaters have remained in place. A properly sized heat pump provides most of the heating and all of the cooling, but at -25 °C, an existing backup system should not be removed in the first year. We prefer clients to see for themselves over the course of a winter, then decide.

For a single-zone or multi-zone wall-mounted heat pump installation in Montreal, Laval, Longueuil, the North Shore or the South Shore, our team comes to your property, measures, calculates—and provides you with a quote specifying the capacity of each head, the length of each connection, and the finish of each line set in black and white.