Installation of a GREE FLEXX R32 electric furnace in Saint-Alexandre

The minimum room area: the A2L rule that nearly changed the entire plan in Saint-Alexandre

In the villages of Haut-Richelieu, the basements of homes built before the 1980s look alike: concrete-coated foundation walls, low ceilings, and a mechanical room sectioned off in a corner by partitions added over the decades. The one in Saint-Alexandre was no exception. It is precisely in this type of space that switching to R32 refrigerant requires a check that most quotes still omit.

We installed a GREE FLEXX R32 electric furnace there—more precisely, a GUD48AH2/G-D(U) air handler with an integrated electric heating section—connected to a GUD60W2/NhE-D(U) outdoor unit. Here is why the first measurement we took on-site was not a heating-load calculation, but a tape measure placed on the floor.

The R32 rule that few contractors apply

R32 is classified as A2L: mildly flammable. Manufacturers therefore place a regulatory chart on the cabinet that cross-references the system’s refrigerant charge with the minimum room area where the indoor unit can be installed. This chart is printed in black and white on the large NOTICE label visible on the Saint-Alexandre unit.

For the FLEXX series, the values are as follows:

The system installed here contains 4.6 kg (162.3 oz) of R32. It therefore required a room of at least 13.7 m², or approximately 147.5 sq. ft. The client’s enclosed mechanical room was barely 90 sq. ft.

A minimum installation height of 0.6 m (2 ft) also applies to this requirement, with the unit needing to be raised to keep any potential leak away from the floor, where refrigerant vapors accumulate first.

How we solved the problem without reducing capacity

Three options were available to us, and we presented them to the client along with their real-world consequences:

1. Reduce the system capacity to bring the charge below 4.6 kg. A simple solution, but one that would have left the home underserved during July’s peak heat.
2. Move the unit to the open part of the basement. Rejected: this would have required rebuilding the entire distribution network.
3. Open the mechanical room to the rest of the basement by removing a non-load-bearing partition added after construction, so that the served volume meets the required area.

We chose the third option. Half a day of work, no modifications to the duct network, and documented compliance in the customer’s file. The unit was then positioned in the corner of the foundation, raised in accordance with the prescribed minimum height.

A rushed contractor would have simply installed the unit and billed the customer. During our HVAC maintenance calls in Montreal, Longueuil, and the North Shore, we regularly see A2L systems installed in enclosed 40-ft² closets. These installations are non-compliant, and that non-compliance comes back to haunt the homeowner during a warranty claim or a pre-purchase inspection.

The Installed System’s Specifications

The TRÉS2 of 19 for this capacity deserves emphasis: it is the highest value in the entire range, higher than that of the smaller models. This is counterintuitive for many homeowners, who instinctively associate “bigger” with “less efficient.” Here, the inverter compressor in the GUD60W2 unit very rarely operates at full load in a home of this size, and it is this extended operation at partial load that produces the seasonal efficiency.

An Unfinished Basement Requires Its Own Precautions

The Plenum and Condensation

The cement-coated foundation wall visible behind the unit stays cold for much of the year, and the relative humidity in an unfinished basement often exceeds 60% in summer. We therefore sealed and insulated the galvanized-sheet-metal supply plenum, applying aluminum tape to every joint. An uninsulated cold duct in a humid basement will condense; water runs along the sheet metal and eventually stains the floor—a defect the customer routinely attributes to a leak in the unit.

The service clearance, measured beforehand rather than afterward

The unit is installed in a corner. We preserved the required front clearance to fully remove the access door, take out the blower, and access the electric heating element blocks. This detail may seem secondary on installation day. It becomes critical eight years later, when a technician has to replace a contactor on a Sunday in January.

The basement condensate drain in the countryside

On this job, the insulated condensate line runs down to a drainage point with a continuous slope and a trap of a depth suited to the fan's static pressure. In South Shore areas without an accessible floor drain, we install a condensate pump with a safety contact connected to the thermostat, so that an overflow stops the system instead of flooding the slab.

Managing the winter peak

A Québec-made load management module is mounted on the plenum, just above the unit, and connected to the low-voltage control circuit.

Its function is simple to understand, yet its effects are underestimated: during winter peak periods, it can restrict the use of the electric heating section—the most energy-intensive part of the system—while allowing the heat pump, which heats down to -30 °C, to maintain comfort. The house stays heated, but the most expensive kilowatt-hour of the year is not consumed.

This type of setup is only worthwhile if the changeover point between the heat pump and the electric elements is configured correctly from the outset. With factory settings, a system often switches to electric heating far too early, and no load-shedding module can compensate for this basic configuration error.

What to check before having an R32 system installed in Montérégie

Questions to ask every bidding contractor

1. What is the system's exact refrigerant charge, in kilograms? A contractor who does not know this has not consulted the technical data sheet.
2. What is the minimum room area required for this charge, and does my room meet that requirement? The answer must be a measured figure, not an impression.
3. Is the minimum installation height of 0.6 m being respected?
4. Will the factory-installed A2L leak detection probe be connected and tested?
5. What electrical panel load calculation was performed before choosing the electrical section's capacity? The indoor unit alone requires an MCA of 7.1 A and an MOCP of 15 A; the outdoor unit requires 39.9 A MCA and 45 A MOCP on its own circuit. The electrical elements are added on top of that.

Rebates: what we confirm and what we do not promise

• The central heat pump component, certified ENERGY STAR and identified by a valid AHRI number — here, 217120761 — is what provides access to the energy-efficiency programs currently in effect.
• The electric furnace, or electric heating section, is not eligible on its own. It serves as supplemental heating.
• Conversion programs are intended for homes moving away from fossil fuels. Each home's status must be verified individually.
• We verify eligibility at the quotation stage using the exact AHRI number. We never calculate a rebate amount based on a program from the previous year.

The warranty and registration

The FLEXX is covered for 10 years, and 12 years when the unit is registered with Wolseley with proof of installation. We complete this process for each of our customers and provide written confirmation with the commissioning report.

Our commissioning protocol

• Weighing the additional charge with an electronic scale, calculated at 0.22 oz per foot beyond the 24.6 ft factory charge
• Leak detection with an electronic detector at every connection before evacuation
• Deep vacuum evacuation with a pressure-rise reading
• Verification of the A2L detection sensor operation
• Measurement of actual airflow and static pressure in the ductwork
• Adjustment of the changeover point to the electric section
• Documented tightening of high-voltage electrical connections

Our approach at AirGreen

At AirGreen, a job begins with measurements and ends with readings. The Saint-Alexandre project illustrates why: without verifying the room's minimum floor area, the system would have operated — and would have been non-compliant, with all the consequences that entails for the owner.

We apply this same protocol to our heat pump, wall-mounted air conditioner, electric furnace, and HVAC installation projects in Montreal, Laval, Longueuil, on the North Shore, and throughout the South Shore. The industry's massive shift to R32 changes the rules of the game: it's better to work with a contractor who knows them before installation rather than afterward.