Installation of a GREE UNIX R32 central system with an integrated electric furnace in Saint-Charles-sur-Richelieu, in the Vallée-du-Richelieu RCM

This time, the electric furnace is actually visible in the photo, and it occupies the upper part of the cabinet

Saint-Charles-sur-Richelieu has approximately 1,735 residents. It is a village of country roads and rivers, known for hosting the Assembly of the Six Counties in October 1837 and then the battle in November of the same year. It has a heritage village core, stone and brick homes, farmland, and one feature that determines everything in HVAC : no natural gas network. Here, heating is electric, period. Baseboard heaters or a central electric furnace.

On this job, the client was replacing an electric furnace that had reached the end of its service life. We installed a GREE UNIX R32 central system, whose air handler incorporates an electric heating element. The photo taken during the connections shows the unit with its panels open: at the top, the electric kit with its own double-pole breakers, heavy-gauge red conductors, terminal block, and control box; in the center, the blower wheel and coil; at the bottom, the service connections, a green cap on the vapor side, and a brass nut on the liquid side.

This is the ideal case for discussing the part that almost nobody documents: the sizing and connection of the electric heating element, and what it does to the home's electrical service.

Why, in this case, the term “electric furnace” is accurate

We often correct the terminology: a central heat pump air handler is not a furnace, because most of the heating is produced by the compressor, not by electric resistance elements. The distinction still matters.

But in a rural home without natural gas, the electric element is not a small defrosting accessory. It is sized to take over the entire heating load if the heat pump fails on January 20. In other words, there really is a complete electric furnace inside the cabinet. It simply spends 90% of the winter doing nothing.

The heating element operates in four situations, and it is worth distinguishing between them because they do not cost the same:

1. Backup heat during very cold weather, when the home's demand exceeds the heat pump's capacity. That is its intended purpose, and its use is minimal when the system is properly sized.
2. Tempering during defrost. The cycle reverses the refrigerant flow to defrost the outdoor coil; without supplemental heat, the air coming from the vents becomes cold for a few minutes. This use is brief but frequent.
3. Emergency mode, if the heat-pump section is out of service. Efficiency: one-to-one.
4. Recovery after a temperature setback, if the thermostat is configured incorrectly. This is the only one of the four that is entirely avoidable, and it is the one that makes the bills skyrocket.

What we installed in Saint-Charles-sur-Richelieu

The load calculation led to the configuration 60 000 (60/60) from the UNIX R32 series, or five nominal tons.

System specification sheet

• Indoor unit (air handler cabinet): GUD60AH2/G-D(U)
• Outdoor unit (condenser): GUD60W2/NhE-D(U)
• AHRI reference code : 217120762
• Cooling capacity: 53,000 BTU/h, modulating from 35,000 to 55,000 BTU/h
• Heating capacity: 54,000 BTU/h, modulating from 35,000 to 60,000 BTU/h
• SEER 2 : 18,5 — EER 2 : 11,7 — HSPF 2 : 10,5 — COP at 8 °C : 3,40
• Airflow: 2,550 m³/h, or 1,500 CFM, at a nominal external static pressure of 125 Pa (0.5 in. w.c.)
• Sound level: 53 dB(A) indoors, 62 dB(A) outdoors
• Heating range: down to −30 °C, with Ultra Heat now maintaining 100% heating capacity at −20 °C
• Cabinet dimensions: 630 × 1,320 × 540 mm (24-13/16 × 51-31/32 × 21-17/64 in.)
• Weight: 90.5 kg (199.5 lb) for the cabinet, 109.5 kg (241.4 lb) for the condenser
• Refrigerant : R32, 4.6 kg charge (162.3 oz)
• Lines: 3/4 in. suction, 3/8 in. liquid — standard length 7.5 m, maximum 30 m, maximum elevation difference 15 m
• Power supply: 208–230 V / 60 Hz / 1 phase — excluding the electric heating element, MCA of 7.7 A and MOP of 15 A at the cabinet, MCA of 39.9 A and MOP of 45 A at the condenser

Why five tons rather than four

Moving from four to five tons in this range changes neither the condenser (the GUD60W2/NhE-D(U) serves both) nor the refrigerant charge (4.6 kg in both cases). What actually changes is the cabinet, the airflow—1,500 CFM instead of 1,200—and the heating capacity, which increases from 48,000 to 54,000 BTU/h.

We chose five tons because the house is large, the calculated load justified it, and above all because in a house without natural gas, every BTU the heat pump does not provide is a BTU produced by electric resistance at a one-to-one ratio. Lowering the balance point by two or three degrees shifts dozens of operating hours per winter from the “compressor” column to the “heating element” column. That is where the real savings are found, far more than in the SEER 2 difference between two models.

One consequence to know: the 4.6 kg charge of R32 requires a significantly larger minimum floor area than the two- and three-ton models, which contain 2.9 kg. The table can be read directly on the unit’s label, and it should be checked before ordering the equipment, not afterward. In this case, the room was more than sufficient.

The electric element: the calculation too many quotes gloss over

Here is the technical part that distinguishes a proper installation from one that will trip the electrical service on the first thaw followed by a cold snap.

From kilowatts to amps

The arithmetic is simple, and no one should sign a quote without doing it. At 240 V single-phase, each kilowatt of resistance draws approximately 4.17 A.

The 125% factor comes from treating heating as a continuous load: a conductor and a protective device must be rated at 125% of the continuous current they serve. This is not an optional safety margin; it is the calculation rule.

Why the kit arrives with several integrated circuit breakers

In the photo, the cabinet’s upper compartment contains several two-pole circuit breakers mounted directly on the unit and supplied by large-gauge red conductors. This is not overengineering: above a certain capacity, the element is divided into several circuits because a single circuit would require conductors of an unreasonably large gauge to pull and connect inside a cabinet.

This division has three practical consequences:

• There must be as many spaces available in the main panel as there are circuits, and physical space in an already well-filled 200 A panel is never guaranteed.
• It enables staging: the circuits do not all come on at the same time, which softens the inrush current and prevents noticeable voltage fluctuations in the lighting.
• It requires clearly identifying each circuit at the panel. A heating element whose circuit breaker cannot be identified is a safety problem for the next technician.

MCA and MOP must be recalculated—the manufacturer says so itself.

The technical data sheet for the UNIX R32 series includes a note that is often overlooked at the bottom of the table: supplemental heat is optional, and the MCA (minimum circuit ampacity) and MOP (maximum overcurrent protection) values must be determined by a certified technician whenever an electrical component is added.

Specifically, the 7.7 A MCA and 15 A MOP listed for the five-ton cabinet concern only the fan and electronics. They say nothing at all about a unit equipped with a 15 or 20 kW element. A quote that copies the figures from the table without recalculating them describes a unit that does not exist.

The electrical service load calculation

This is the step most often skipped, and the one that costs the most when it resurfaces later. In a fully electric home on the South Shore or in rural Montérégie, you have to add up:

• the heating load, including the baseboard heaters retained in rooms not served by the ducts;
• the heat-pump condenser, with its 39.9 A MCA and 45 A MOP;
• the cabinet's electric heating element, at its actual rating;
• the water heater, stove, dryer, and well pump, if applicable;
• and, increasingly often, a charging station for an electric vehicle.

The total determines whether a 200 A service is sufficient, whether a load-management device is required, or whether an upgrade should be considered. We perform this calculation before proposing equipment because the answer sometimes changes the recommendation. Sometimes the right advice is a smaller element while keeping a few existing baseboard heaters as backup, rather than an oversized element that forces a service upgrade.

Make the element run as little as possible

Installing the element is only half the job. The other half is making sure it stays off.

• Outdoor-temperature lockout. The heating element must not be allowed to start above a set temperature, generally around the calculated balance point. Without this lockout, it will come on in October.
• Proper thermostat staging. The compressor must have priority, and supplemental heat should be added only after a sustained temperature differential, never on the first call.
• Prudent temperature setbacks. With a resistance-heating system, lowering the temperature by 3°C at night saves energy. With a central heat pump, a sudden recovery calls on the heating element and wipes out the savings. We configure steady setpoints and explain this to the customer because it is counterintuitive.
• Defrost tempering set to the lowest useful level. Just enough so the discharged air is not cold, and no more.

The refrigerant line routed through a finished wall, and everything that entails

The second part of this work can be seen on the wall, to the left of the unit: a strip of freshly applied joint compound running from ceiling to floor, and a refrigerant line coming out of the wall, making a wide loop, then rising toward the cabinet, held in place by two clamps.

Why open the drywall instead of running along the wall

Running the line visibly is faster and cheaper. It is also visible forever in a finished room, and it exposes the line's insulation to impacts. When the space is finished and the owner plans to use it, we often prefer to open a strip of drywall, run the line through the cavity, then close it back up. The result costs a few extra hours, but it is clean, protected, and durable.

However, this choice entails a series of obligations that must be understood before cutting the first piece of drywall.

The rules for a concealed line

• No joints inside the wall. A braze or fitting in an inaccessible cavity is a leak point that cannot be inspected or repaired without demolition. The concealed line must be continuous from one end of the hidden section to the other.
• Continuous, intact insulation. The suction line is cold in cooling mode. A section of insulation that is crushed or interrupted inside a cavity causes condensation inside the wall, invisible until the stain appears on the paint.
• Mechanical protection at penetrations. Where the line passes through a stud or plate, it must be protected against the screws and nails used by the next renovator. A protection plate costs two dollars and prevents a puncture of the liquid line ten years from now.
• Conduit at critical passages. A sleeve allows a section to be removed and replaced without reopening the entire height of the wall.
• Separation of services. The refrigeration line must not share a cavity with an electrical conductor without the required separation.

The loop and the clamps

The visible curve where the line exits the wall is not decorative. An expansion loop absorbs movement in the copper tubing—copper expands and contracts with the refrigerant temperature, and a line rigidly embedded at both ends eventually transfers this stress to its fittings.

It plays a second role, even more important in a finished room: it decouples vibrations. A drywall wall is a membrane. A refrigeration line rigidly fastened to a wooden frame turns the structure into an instrument, and the compressor's hum can be heard in the room above. The clamps are therefore installed with an interposing material and tightened without crushing the insulation.

Close, sand, paint

An installation that leaves a wall torn up is not finished. Repairing the drywall, applying joint compound, sanding, and repainting are part of the work when we choose to run through a finished wall. We discuss this during the quote, and the client knows in advance what will be opened and what condition the room will be returned in.

The service fittings, the green cap, and the brass nut

At the bottom of the cabinet, two fittings are accessible from outside the casing. This is one of the real advantages of this product line: external service valves and electrical terminals, designed to be connected without disassembling the unit.

The vapor side has a coloured cap, while the liquid side has a brass fitting. Two procedural points on which we do not compromise:

• The caps must be put back in place and tightened. They provide the secondary seal for the Schrader valve. A cap left at the bottom of the pan is a slow leak waiting to happen.
• A flared connection must be tightened to the specified torque, not by feel. Too little, and it leaks; too much, and the flare splits. A torque wrench is not a luxury accessory on an R32 system, where the 4.6 kg charge is weighed and recorded.

The mistakes we see most often with this type of replacement

1. Copying the MCA and MOP from the table without recalculating them after the electric heating element is added.
2. Failing to verify the available space in the electrical panel before ordering a multi-circuit kit.
3. Failing to set the backup lockout according to outdoor temperature, causing the heating elements to operate in the fall.
4. Programming deep thermostat setbacks as was done with an electric furnace.
5. Brazing a joint inside a finished wall, making any future leak search destructive.
6. Rigidly fastening the line to the framing of an occupied room and transmitting vibrations throughout the house.
7. Undersizing the heat pump on the assumption that the heating element will compensate. It does, in fact, at one kilowatt for one kilowatt.
8. Neglecting mechanical protection for the line where it passes through studs.

Grants and eligibility

Replacing an entirely electric heating system with an efficient central heat pump is the scenario targeted by the energy-efficiency programs available in Quebec. Eligibility is always verified using the AHRI reference code for the exact installed combination—here, 217120762—not by the brand or the indoor unit model alone. Pairing an indoor unit with a different condenser produces another code, different ratings, and sometimes no eligibility at all. At AirGreen, we include this code on the quotation and assist our customers with preparing their application. Since amounts and conditions are revised periodically, we always recommend confirming them before signing.

An honest note about the documentation

We read technical specifications line by line, and we prefer to point out anything that seems wrong rather than let it circulate.

The cover page for this product line displays a SEER 2 of 18.0, an EER 2 of 12.5, an HSPF 2 of 10.0, and a COP of 3.60. These four figures do not belong to the same unit: the EER 2 of 12.5 and the COP of 3.60 are those of the two-ton model. The model installed here shows 11.7 and 3.40, with a SEER 2 of 18.5 and an HSPF 2 of 10.5. The table is reliable; the cover page is a promotional summary.

Another point, with more serious consequences in the field: the version of this same product line distributed under another commercial label expresses the refrigerant charge in pounds when it is actually in kilograms. The verification is immediate—4.6 kg corresponds exactly to the indicated 162.3 oz, or approximately 10.1 lb. A technician who weighed 4.6 lb into the cylinder would install less than half the charge.

Our installations in the Richelieu Valley and Montérégie

Saint-Charles-sur-Richelieu joins a series of projects carried out along the river and in the neighboring regional county municipalities: McMasterville, Saint-Mathias-sur-Richelieu, Saint-Roch-de-Richelieu, Saint-Sébastien, Venise-en-Québec, as well as Saint-Liboire, Sainte-Madeleine, and La Présentation toward Saint-Hyacinthe. None of these projects presented the same challenge: a 42-inch crawl space, an attached garage ceiling, a raised slab that cannot be drilled, a cluttered storage room, a basement in a flood zone, and here, a finished wall to open and an electrical component to integrate into an already loaded panel.

At AirGreen, we design, install, and maintain central heat pumps, wall-mounted heat pumps, wall-mounted air conditioners, multi-zone systems, and commercial solutions in Montreal, Laval, Longueuil, on the North Shore, and on the South Shore. We hold RBQ licence 5645-9605-01, including the ventilation, refrigeration, and electrical subcategories, allowing us to handle the electrical portion of an electric furnace replacement without subcontracting the most delicate part of the work.

If your home is heated with electricity and your furnace is nearing the end of its life, the first question is not the appliance brand. It is what your electrical service can handle, and at what temperature your future heat pump will hand over to the resistance heaters. We measure, calculate, and provide you with both answers in writing.