Installation of a GREE FLEXX R32 central system with an integrated electric furnace in Saint-Paul-de-l'Île-aux-Noix

What you see when the panels are still open

Most installation photos show a closed, clean machine ready for delivery. This one shows the opposite: the GREE FLEXX R32 central system installed in a basement in Saint-Paul-de-l'Île-aux-Noix, with the panels removed, the electrical compartment exposed, and the blower visible.

This is the condition in which an installation should be inspected. Once the panels are screwed back on, everything looks the same. At AirGreen, we believe customers have the right to see inside before the unit is closed up, and we systematically photograph every compartment. This article describes what is behind the sheet metal, why each component is there, and what this means for an all-electric home in Haut-Richelieu.

The electric furnace is in the cabinet, not in the ductwork

The upper-left compartment of the unit contains the component that answers the auxiliary-heating question: an approved electric heating assembly, mounted inside the indoor unit's cabinet.

It shows two integrated two-pole circuit breakers, each powering a bank of elements — in other words, a two-stage auxiliary heater. Next to them are the contactors, sequencers, thermal limiters, the 24 V control transformer, and the red and black power wiring harness.

This configuration is not an installer preference. It follows directly from a requirement stated on the manufacturer's warning label.

Why the location of auxiliary heating is no longer a minor detail with R32

R32 is a refrigerant classified as A2L, meaning it is mildly flammable. The label affixed to the unit states a restriction that systems using R410A did not have: auxiliary devices that could constitute an ignition source must not be installed in the ductwork, except for those approved for use with this specific unit.

In other words, in an all-electric home where additional heating capacity must be added, two options exist on paper — an electric heater installed in the plenum, or a set of heating elements integrated into the unit — but only one is automatically compliant: the one the manufacturer has approved for its own equipment.

The practical benefits of the integrated assembly add up:

• Certification already obtained. No need to verify anything with the manufacturer, and no gray area in the event of an insurance or warranty claim.
• Factory interlock with the fan. The heating elements cannot engage without airflow, and the logic is factory-wired rather than recreated on site. This is the number-one weakness of plenum-mounted setups behind a variable-speed unit.
• Integrated circuit breakers. The supplemental heat can be disconnected at the unit, within the technician’s reach, without making repeated trips to the main panel.
• A single service point. The filter, coil, blower, controls, and heating elements are all housed in the same cabinet.
• No added ignition source in the ductwork.

We recommend this setup on all our R32 projects in Montérégie, on the South Shore as well as in Montréal and Laval.

Sizing the stages without oversizing

The number of stages is not cosmetic. Single-stage supplemental heat operates on an all-or-nothing basis: as soon as it is called for, the full electrical capacity is added to that of the compressor. Two stages allow only what is actually missing to be added.

The calculation method remains the same as for any supplemental heat:

1. House heating load at the area’s winter design temperature.
2. Heat pump capacity at that same temperature, taken from the manufacturer’s extended performance tables—not from the operating range shown on the sales sheet, which only indicates that the unit operates down to -30 °C, without saying how much it produces at that temperature.
3. The difference determines the total heating-element capacity.

To convert: 1 kW = 3,412 BTU/h. A house with a 20,000 BTU/h design-temperature heating deficit needs about 6 kW of supplemental heat, not 15.

Oversizing costs you twice. First at installation, because excessive capacity increases the building’s electrical load calculation and can trigger an unnecessary service upgrade. Then every winter, because one large stage kicks in at full capacity to make up a two-degree gap.

The control compartment: what clean wiring means

To the right of the power block is the main control board, with its low-voltage terminal block and bundle of thin wires—white, yellow, blue, and black.

A well-made control compartment can be recognized by concrete signs visible in the photograph:

• Harnesses secured at regular intervals, kept away from moving parts and hot surfaces
• Wire clamps at sheet-metal openings — a wire running over an unprotected sheet-metal edge will eventually become worn through, generally after a few years of vibration
• Clear separation between high voltage and low voltage, each in its own compartment, with no wiring harness passing through
• Service lengths preserved and coiled, with no taut wire that will need to be extended the first time a component is replaced
• Accessible low-voltage terminal block without removing the control board

This last point deserves a word. On a conventional 24 VAC thermostat system like this one, the terminal block receives the power supply, the cooling call, the heating call, the fan command, the reversing-valve command, and the auxiliary-heat calls. One day, someone will have to replace a thermostat at this terminal block. If access requires removing the control board, the job goes from twenty minutes to two hours.

We photograph the terminal block and the control board before closing it back up, and provide these images to the customer with the installation file. It costs nothing to do, and the first time a technician arrives on-site without ever having seen the equipment, they are worth a great deal.

The blower and the cabinet’s interior insulation

The central compartment contains the centrifugal blower in its galvanized scroll housing, driven by an electronically commutated motor. The cabinet walls and bottom are lined with an insulation with a metallized surface, visible in a silver checkerboard pattern behind the scroll housing.

This interior insulation serves two purposes that are rarely distinguished:

• Acoustic. A blower of this size is audible in an unfinished basement. The lining absorbs some of the airflow noise before it is transmitted to the cabinet’s sheet metal. The technical specifications list 52 dB(A) for the indoor unit, a value measured with the cabinet closed and the insulation in place.
• Thermal. In cooling mode, the inside of the cabinet drops well below the dew point of a Quebec basement in July. Without insulation, the outer surface of the sheet metal would become covered in water. A cabinet that “sweats” does not have a leak: it has a thermal bridge.

A direct maintenance implication: this insulation must never be torn out, punctured, or replaced with ordinary batt insulation during a repair. We have already opened units whose interior insulation had been removed to access a component and never put back. The unit works; it is simply noisier and wets the floor.

The base, the shims, and the issue of water

The unit does not sit directly on the slab. It is installed on a custom-built galvanized sheet-metal return-air plenum, which itself rests on wooden timbers laid on the concrete. Everything is sealed with aluminum tape, with a filter access panel on the front.

This is not a construction detail. It is a design decision, and in Saint-Paul-de-l'Île-aux-Noix it has a particular context.

Elevating mechanical equipment along the Richelieu

The municipality borders the Richelieu at the outlet of Lake Champlain. The area experiences flooding events, and the memory of the major flood in spring 2011 remains vivid among waterfront property owners. Part of the housing stock consists of former seasonal residences converted into permanent homes, often with a basement or crawl space at the water table level.

In this context, the height at which mechanical equipment is installed is not an aesthetic question:

• A unit installed flat on the slab is lost as soon as a few centimeters of water enter the basement. The control board and the heating element assembly are in the lower third of the room's usable volume.
• A unit elevated on a base and a return-air plenum gains meaningful clearance at no significant additional cost.
• The electrical panel, water heater, and central system should ideally be addressed together in this regard. On this job, the electric water heater visible on the left is a natural candidate for elevation when it is next replaced.

We systematically raise this issue when preparing quotes in municipalities along the Richelieu, from Saint-Jean-sur-Richelieu to Lacolle, and in the low-lying areas of the South Shore. The owner decides; they decide with full information.

Leveling on a floor that is not flat

An older basement slab is rarely level. The wooden timbers and shims visible beneath the base are used to correct this.

An out-of-level unit does not drain its condensate pan properly. Water pools in one corner of the pan, biological sludge builds up, the drain clogs, and the pan overflows. This is one of the most common and frequent causes of water damage associated with a central system, and it can be corrected with a carpenter's level during installation.

Install while the basement is still open

The basement walls are framed but not closed in. The insulation panels are installed behind them, and the electrical wiring is still exposed. The HVAC work takes place during the basement finishing.

This is the best possible sequence, and it deserves to be planned intentionally rather than endured.

What we coordinate with the contractor before the walls are closed

1. Permanent service clearances. The frontal clearance required to open the panels and remove the coil is determined before the framing is installed, not afterward. A wall erected 18 inches from the front of the unit turns every service visit into a disassembly job.
2. Filter access, clear and at floor level, without having to go around a wall or move storage.
3. The unit's removal path. On replacement day, fifteen years from now, the cabinet will have to come out. Door width and stairway access must be planned now.
4. The duct layout, finalized before the partitions establish the available geometry. Adding one more elbow later to go around a wall that was not in the quote costs static pressure for the system's entire service life.
5. Photographs of everything that will be concealed: ducts, wiring, refrigerant piping, condensate line. These images are worth their weight in gold at the first service call.
6. The mechanical room's return air, if the room is to be enclosed. This point directly relates to the minimum area requirement associated with A2L refrigerant: this unit, charged with 4.6 kg of R32, requires 13.71 m² (147.5 ft²) according to the label's table. An open basement comfortably meets this value. An enclosed 3 m by 2 m mechanical room does not. The partition that does not yet exist can make the installation non-compliant.

This sixth point is the one we most often see missed on basement finishing projects. The unit is properly installed in an open space; six months later, a renovation contractor builds a wall around it.

Technical data for the system installed in Saint-Paul-de-l'Île-aux-Noix

Eligibility for rebate programs

The system carries ENERGY STAR certification and a certified AHRI number (217120761), the two documents normally required for the application. We verify eligibility using the exact indoor and outdoor unit combination before signing, because a stated efficiency rating that does not match the combination actually installed remains the main reason for rejection. Thresholds and amounts change from year to year; we check them up to date rather than promising them from memory.

Mistakes to avoid with this type of installation

• Installing the backup heater in the plenum without verifying its approval for an A2L appliance
• Sizing the backup heat “to be safe” rather than according to the actual shortfall at the balance point
• Choosing single-stage backup heat for a variable-speed system
• Installing the appliance directly on the slab in a flood-prone area
• Neglecting leveling and blocking the condensate pan drainage
• Closing the basement walls before determining the service clearances and exit route
• Building a partition around an A2L appliance without rechecking the required minimum area
• Closing the panels without photographing the control compartment

At AirGreen, we carry out this type of HVAC installation in Saint-Paul-de-l'Île-aux-Noix, throughout Haut-Richelieu and Montérégie, as well as in Montreal, Laval, Longueuil, the South Shore, and the North Shore. Whether you need a central heat pump with an integrated electric furnace installed, an existing system replaced, or HVAC maintenance, our team visits your home, takes measurements, coordinates with your other trades, and provides a quote based on what your basement actually allows.