Replacing baseboards with a central system in a finished mechanical room: the Henryville project
About forty minutes from Montreal, in Haut-Richelieu, homes in Henryville often share the same profile: electric baseboard heating, no central air conditioning, and a finished mechanical room where the hot water tank, washer-dryer, and electrical service entrance coexist. This is exactly the context in which we stepped in to install a GREE FLEXX R32 electric furnace paired with a central heat pump.
The owner called us in June, after spending a third summer moving a portable air conditioner from room to room. His request was simple: get central air conditioning without demolishing the mechanical room and without causing the electricity bill to rise the following winter.
What we installed
The selected configuration:
- GREE GUD24AH2/G-D(U) indoor unit with an integrated 10 kW electric heating section
- GREE GUD36W2/NhE-D(U) outdoor unit, R32 refrigerant
- Power supply network in an insulated round duct, with a manual balancing damper
- 24 VAC conventional thermostat, factory-installed Wi-Fi module
| Technical data | Value |
|---|---|
| Rated cooling capacity | 24,000 BTU/h |
| Rated heating capacity | 23,000 BTU/h |
| Modulating range | 12,000 to 30,000 BTU/h |
| SEER2 | 18 |
| HSPF2 | 10 |
| EER2 | 12,5 |
| COP | 3,6 |
| AHRI number | 217120759 |
| Certification | ENERGY STAR |
| Heating range | up to -30 °C |
| Cooling range | -15 °C to 54 °C |
| R32 refrigerant charge | 2.5 lb (88.2 oz) |
| Indoor unit net weight | 135.6 lb |
| Outdoor unit sound level | 60 dB(A) |
The 3.6 COP of this unit is the best in the entire FLEXX lineup. Put in billing terms: under nominal conditions, each kilowatt-hour consumed delivers approximately three and a half times the heat that an electric baseboard would have produced with the same kilowatt-hour. That is where most of the savings come from, not from the efficiency of the electric heat section—which remains, by nature, at 100% and not a point higher.
A vertical installation in a room the client uses every day
The constraint of this project was not height, as it is in many basements on the South Shore, but the finish. The mechanical room was already painted, lit, and used as a laundry room. Mechanical equipment in this type of room must be treated as furniture as much as equipment.
Silence starts with the structure, not the unit
We placed the cabinet on an insulated base rather than directly on the slab, and avoided any rigid contact between the unit's sheet metal and the finished wall. The point most installers overlook: the first duct section. A rigid duct screwed directly to the unit's outlet transmits every fan vibration into the structure and turns the adjacent room into a sounding board. We systematically install a flexible connector and pay close attention to the radius of the elbows.
Insulated round ductwork: a technical choice, not an aesthetic one
The supply network was built using insulated round ductwork rather than rectangular ducts. Three reasons:
- Less pressure loss for the same cross-section, leaving the fan the margin it needs to operate at low speed.
- No condensation on cold surfaces in summer, thanks to the insulation and its continuous vapor barrier.
- A possible route between the joists without reducing the remaining headroom in the basement.
The manual damper visible on the black duct allows us to balance the airflow to the upper floor after a few weeks of actual use. We systematically return to make this adjustment: balancing performed on the day of installation, in an empty house at a stable temperature, never reflects actual use.
The ampacity plate: the document no one reads, yet it determines everything
A large bilingual plate on the cabinet displays a table of the minimum circuit ampacity (MCA) and maximum overcurrent protection (MOCP) for each power rating of the electric heating section. It is the most important document in the entire installation, and the one that quick quotes ignore.
The indoor unit alone requires very little: MCA of 4.7 A, MOCP of 15 A at 208–230 V. But every kilowatt added to the electric section increases the ampacity, and therefore the cable and breaker rating. The outdoor unit, for its part, requires a separate circuit with an MCA of 27.7 A and an MOCP of 30 A.
Before confirming the 10 kW electrical capacity, we therefore:
- Recorded the panel's existing load and verified the available capacity, taking the water heater, well pump, and dryer into account
- Removed the decommissioned baseboard heaters from the calculation, freeing up a significant portion of the load
- Verified that the selected heating section remained below the actual capacity of the service entrance
We saw electric furnaces installed without this calculation, first in a house in Longueuil and then in another on the North Shore. The result was identical in both cases: the main breaker tripped during the first deep freeze, exactly when the house needed its full capacity.
Mistake to avoid: oversizing the electric heat section “just in case”
The temptation to order 15 or 20 kW for peace of mind is strong. It is counterproductive. An oversized electric heat section costs more in wiring, requires a larger electrical service, and—most importantly—encourages a thermostat setting that starts it too early, bypassing the heat pump, which is nevertheless the efficient part of the system. We size the electric heat section for the region's design temperature, not for an imaginary winter.
The refrigerant lines, R32, and the A2L sensor
The refrigerant lines—3/8 in. liquid, 3/4 in. gas—were insulated along their entire length, including inside the mechanical room. An uninsulated gas line, even over just three feet, condenses in summer and leaves a puddle beneath the unit that the customer then mistakenly attributes to a drain defect.
The system is precharged for 24.6 ft (7.5 m) of piping. Beyond that, a calculated top-up of 0.32 oz per foot is required. The FLEXX allows up to 98.4 ft (30 m) between the two units and 49.2 ft (15 m) of elevation difference, providing considerable flexibility to position the outdoor unit away from the bedrooms—a choice we systematically recommend, even though the unit does not exceed 60 dB(A).
Because R32 is classified as A2L, the unit incorporates a factory-installed leak detection sensor, and the cabinet bears the corresponding regulatory labeling. We perform an electronic leak-detection test on every flared connection before evacuation, followed by a deep vacuum and a pressure-rise reading. A rushed evacuation completed in fifteen minutes is the most common cause of premature compressor failures we encounter in HVAC maintenance.
What homeowners in Haut-Richelieu should verify before replacing their heating system
Subsidies: distinguishing what is eligible from what is not
This is the subject surrounded by the most misinformation. This is our interpretation, which we verify with every submission:
- The central heat pump certified by ENERGY STAR, identified by a valid AHRI number such as 217120759, is the component that grants access to the energy-efficiency programs currently in effect.
- The electric furnace alone is not an eligible subsidized item. It provides supplemental heat, not an energy-saving measure.
- Conversion programs are intended to eliminate fossil fuel use. A home already heated with electric baseboards, like this one, is not eligible.
- Amounts, caps, and technical criteria change from year to year. We never calculate a subsidy without confirming the program on the exact project date.
The warranty is determined in the weeks following installation
The FLEXX comes with a 10-year standard warranty, extended to 12 years when the unit is registered with Wolseley along with proof of installation. We handle these steps and provide the customer with written confirmation. Two additional years of compressor coverage represent real value that too many homeowners lose through a simple administrative oversight.
The setting that determines your winter bill
The FLEXX works with a conventional 24 VAC thermostat, giving the homeowner the freedom to change models or integrate it into an existing home automation system. But that freedom comes with a responsibility: the changeover point to the electrical section must be configured according to the actual performance of the heat pump, which heats down to -30 °C.
A changeover point left at the factory settings, often around -5 °C, amounts to paying for a high-performance heat pump and then heating with baseboards for half the winter. We configure this setting during commissioning and explain it to the customer, with the supporting measurements.
Our recommended maintenance for this type of system
- Filter: inspection every three months. In a laundry room, the textile lint load is higher than elsewhere, so the filter becomes clogged more quickly.
- Coil and condensate pan: annual cleaning before the air-conditioning season.
- Electrical section connections: checking the tightening torque once a year. Heating cycles cause expansion and loosening.
- Outdoor unit: keeping the base clear of snow and ice in winter, and cleaning the condenser in spring.
- Balancing dampers: readjustment when the season changes if comfort varies from one floor to another.
Our approach at AirGreen
At AirGreen, we spend more time on what comes before installation than on the installation itself: assessing the space, calculating the load room by room, verifying electrical capacity, routing refrigerant lines, and designing the ductwork. This Henryville project followed the same method as our heat pump, wall-mounted air conditioner, and electric furnace projects in Montreal, Laval, Longueuil, on the North Shore, and throughout the South Shore.
A properly sized and commissioned central system should go unnoticed. That is precisely the result we aim for.