A six-foot basement, three beams in the way, and a central system that still had to fit
The Sainte-Angèle-de-Monnoir project reminded us of something we often repeat to our South Shore customers: the equipment choice matters, but it is the basement geometry that determines the real success of an HVAC installation. In this home in the Rouville RCM, the mechanical room is barely more than six feet high beneath the joists, two load-bearing wooden columns frame the equipment location, and the existing duct network already occupied all the available height.
The client contacted us with a seemingly simple request: replace an aging electric heater and add central air conditioning without turning the basement into a mechanical room. We proposed a GREE FLEXX R32 central system, consisting of a GUD36AH2/G-D(U) horizontal-airflow air handler equipped with an integrated 15 kW electric heating section, and an outdoor unit, GUD36W2/NhE-D(U).
Why a horizontal airflow configuration changed everything
Most air handlers are designed for vertical installation, requiring 60 to 70 inches of overhead clearance. That was impossible here. The FLEXX's horizontal airflow design allowed us to lay the unit beneath the joists, between the two columns, with a cabinet measuring 21 1/4 x 48 1/5 x 21 1/4 inches and a net weight of 163 lb.
This purely mechanical detail spared the homeowner three expenses they had not budgeted for:
- No slab excavation to create an equipment pit.
- No reconstruction of the main plenum: we connected the unit to the existing galvanized sheet-metal supply duct, visible across the full width of the room.
- No relocation of the HRV: the large black flexible duct from the heat recovery ventilator remained exactly where it was, with its original connections.
The real job-site constraints and how we resolved them
Routing the refrigerant line
The outdoor unit was positioned on the north side of the house, away from the bedrooms. The refrigerant line — 3/8 in. liquid, 3/4 in. gas — was routed along the rim joist, then through the foundation with a sealed sleeve and a firestop. The FLEXX allows up to 98.4 ft (30 m) of piping between the two units and 49.2 ft (15 m) of vertical separation, with a factory precharge covering the first 24.6 ft. We had approximately 34 ft of actual piping, so an additional R32 refrigerant charge was calculated at 0.32 oz per excess foot, weighed on an electronic scale, and recorded on the commissioning sheet.
A common mistake we see among other contractors in Montréal and the North Shore: charging “by feel” or relying solely on pressure. On an inverter-compressor system like the FLEXX, overcharging by just a few ounces is enough to reduce performance and trigger protection codes during a heat wave.
The condensate drain
In the job-site photo, you can see the P-trap in PVC with its red service caps, to the left of the unit. A basement at slab level rarely has a natural slope toward a floor drain. We installed the trap with the trap-seal depth required by the fan’s static pressure, then provided a continuous slope of 1/8 in. per foot toward the existing drain. A trap that is too short on a negative-pressure unit draws air through the drain and allows water to back up into the pan: this is the number-one cause of water damage we encounter during service calls in Montérégie.
The electrical supply
This is the point homeowners underestimate the most. The indoor unit alone requires little — MCA of 5.3 A, MOCP of 15 A at 208–230 V. But once the 15 kW electric heating section is added, the load increases and requires its own dedicated circuits, with separate breakers depending on the element banks. The outdoor unit, meanwhile, requires an MCA of 27.7 A and an MOCP of 30 A.
Before ordering the equipment, we therefore performed an electrical panel load calculation in accordance with Chapter V of the Québec Construction Code. At this site, the 200 A panel had the required capacity. That is not always the case: in a Longueuil home last fall, the same exercise revealed that a 100 A panel could not handle the requested electric furnace, so we directed the client to upgrade the service entrance before any installation. It is better to know this before the equipment is delivered than afterward.
The actual performance of this FLEXX R32 system
Once operational, the installed system offers the following specifications:
| Data | Value |
|---|---|
| Rated heating capacity | 34,000 BTU/h |
| Rated cooling capacity | 34,000 BTU/h |
| Modulation range | 18,000 to 37,000 BTU/h |
| SEER2 | 18 |
| HSPF2 | 10 |
| EER2 | 12 |
| COP | 3,2 |
| AHRI number | 217120760 |
| Certification | ENERGY STAR |
| Heating range | up to -30 °C |
| Cooling range | -15 °C to 54 °C |
| Refrigerant | R32, 2.9 lb (102.3 oz) |
| Outdoor sound level | 61 dB(A) |
The point that matters most to our South Shore clients is the heating range down to -30 °C. In practical terms, the heat pump remains the primary heat source during virtually the entire winter in Montérégie, while the integrated electric furnace operates only as backup during cold snaps or defrost cycles. This is exactly the opposite of a poorly configured dual-fuel system, where the electric elements take over far too early and cause the bill to skyrocket.
Modulating capacity rather than oversizing
The modulation range of 18,000 to 37,000 BTU/h was decisive in our recommendation. We performed a room-by-room load calculation rather than applying the still-too-common rule of thumb: “one ton per 600 sq. ft.” An oversized unit short-cycles, dehumidifies poorly in summer, and prematurely wears out its compressor. Here, the calculated load was in the lower third of the range for most of the season, giving the system the flexibility to run for long periods at low output—the setting at which it is most efficient and quietest.
What this project teaches us about central electric heating in Montérégie
The A2L leak sensor is not an accessory
The FLEXX uses R32, an A2L-classified refrigerant. The A2L leak-detection sensor is factory-installed and integrated into the cabinet, as is the factory-installed Wi-Fi module. We emphasize this point to clients comparing quotes: an installer who disables or bypasses this sensor to avoid false alarms compromises both safety and the warranty. The proper approach is instead to verify the clearance around the cabinet and the tightness of the flared connections with an electronic detector, which we systematically document.
The warranty is lost through administrative negligence
The FLEXX is covered by a 10-year standard warranty, extended by 2 additional years when the product is registered with Wolseley with proof of installation. We handle this registration for each of our clients because we have seen too many homeowners lose two years of coverage because a form was never completed.
Subsidies: what really applies
This is the area where the information circulating online is the most approximate. Here is how we present it to our clients in Montreal, Laval, Longueuil, the North Shore, and the South Shore:
- The system's central heat pump, certified ENERGY STAR with a valid AHRI number, is what qualifies for the energy-efficiency programs currently in effect.
- The electric furnace, or the electric heating section considered on its own, is not an eligible item for subsidies: it is a supplement, not an energy-saving measure.
- Conversion programs are intended for homes that are switching from a fossil fuel. A home already heated with electricity, such as the one in Sainte-Angèle-de-Monnoir, is not eligible.
Amounts and criteria change from year to year. We therefore verify eligibility at the time of submission, using the exact AHRI number for the proposed configuration, rather than promising an amount that may no longer exist on the installation date.
The conventional thermostat, an underrated advantage
The FLEXX operates with a conventional 24 VAC thermostat rather than a proprietary controller. For a homeowner, this means genuine freedom: integration with an existing home automation system, the option to replace the thermostat without relying on a single model, and simplified diagnosis by any qualified technician. We used this project to precisely configure the changeover point to electric heating, a setting many people leave at the factory defaults and which, when poorly adjusted, can cost several hundred dollars per winter.
Our maintenance recommendations for this type of installation
- Filter: check every 3 months; replace based on actual dirt accumulation. A clogged filter reduces airflow and causes the thermal limit switches in the electrical section to trip.
- Indoor coil: annual cleaning. The coil's blue fins, visible when the cabinet is opened, collect dust and carpet fibers.
- Drain and trap: annual flushing before the cooling season.
- Outdoor unit: clear snow and ice from around the base in winter; clean the condenser in spring.
- Electrical tightening: annual inspection of the heating-section connections, where thermal cycles cause loosening.
Our approach at AirGreen
At AirGreen, we refuse to treat an HVAC installation as a simple equipment delivery. On this project in Sainte-Angèle-de-Monnoir, the time invested before ordering—the site survey, load calculation, electrical panel inspection, and refrigerant line layout—represented more hours than the installation day itself. This preparatory work is precisely what makes the difference between a system that operates trouble-free for ten years and one that generates service calls starting with the first winter.
We apply the same method to all our heat pump, wall-mounted air conditioner, electric furnace, and HVAC maintenance projects in Montreal, Laval, Longueuil, on the North Shore, and on the South Shore. If your basement seems too low, too cluttered, or too complicated, that is generally exactly the kind of project we prefer.