The basement, the room most HVAC installations handle poorly
In Chambly, a large share of the housing stock consists of bungalows, cottages, and split-level homes built between the 1970s and 2000s, almost all with a finished basement or one in the process of being finished. And nearly all share the same comfort problem: the basement is cold in winter, damp in summer, and no one goes down there in February.
This project illustrates a different approach. The homeowner was finishing their basement when they called us, and that timing is precisely what made the installation better than it would have been six months later.
Install during the renovation, not afterward: the decisive advantage
In the construction photo, the bottom of the wall is still open: you can see the rigid insulation board applied to the foundation and the furring strips awaiting drywall. The indoor head is already in place, at the top of the finished wall.
This sequence of operations is no accident.
What this makes possible in practice
The refrigerant lines disappear into the wall. With a retrofit installation, you either have to run them along the wall in a PVC line set cover, or drill and work around obstacles. When the installation is coordinated with the renovation, the lines, interconnection cable, and condensate drain run through the wall cavity or ceiling before the drywall is installed. The visual result: nothing. Just the unit on a clean wall.
The routing is optimal rather than merely possible. Without finishing constraints, we choose the shortest and most direct path to the outdoor unit. Less length, fewer bends, less pressure loss, better efficiency.
The condensate drain gets a proper slope. This is the critical point in a basement, and we’ll come back to it below.
The wall penetration is done cleanly, on the correct side, with the right sealant, without having to work around a finished wall and a new floor.
Practical advice
If you plan to finish your basement in the next few months and are considering a wall-mounted heat pump, call an HVAC contractor before the drywall is installed, even if the installation will take place later. A thirty-minute coordination visit makes it possible to prepare the routes. This is one of the most cost-effective pieces of advice we give, and the one homeowners most regret not receiving in time.
The basement condensate drain: the real technical challenge
An indoor unit in cooling mode produces water. On the ground floor or upper floor, this water drains by gravity to the outdoors, along the same route as the refrigerant lines.
In a basement, there is nowhere to run it downward. The unit is already below the level of the exterior ground.
Three solutions are available, in order of preference:
- A slope toward an existing drain, if the configuration allows it and local code permits it. This is the most reliable solution because it has no mechanical parts.
- A dedicated condensate pump, installed with the indoor unit. This is the most common solution in a basement. It works well, but it adds an electrical component that can fail—which is why it is important to choose a quality pump with a high-level safety switch that shuts off the unit rather than allowing it to overflow.
- Running the condensate uphill to a drain point on the floor above, when nothing else is possible.
The mistake we correct most often: a drain “raised” a few centimetres to get around an obstacle, without a pump. Water does not flow uphill. It accumulates in the drain pan, overflows through the front of the unit, and spills onto the new basement floor in the middle of a heat wave. The homeowner thinks it is a manufacturing defect. It is an installation defect.
The question few contractors ask: wall-mounted unit or console?
We need to be frank about one point because it determines customer satisfaction in a basement.
A wall-mounted indoor unit installed high on the wall is excellent for cooling and less natural for heating.
The reason is physics. Warm air rises. A high-mounted unit blowing warm air initially feeds the ceiling, and you have to rely on air circulation for the heat to descend. In a room with a low ceiling and a concrete floor beneath the finished flooring, this stratification is noticeable: your upper body is comfortable, but your feet are cold.
Conversely, for cooling, a high-mounted indoor unit is ideal: cold air naturally descends and sweeps through the room.
How we decide
We ask three questions:
- What is the basement's main use? A family room used in the evening year-round does not have the same needs as a storage area that is only occasionally air-conditioned.
- Will the existing supplemental heating remain in place? On this project, the electric baseboard heater was kept. It provides supplemental heat during extreme cold and offsets stratification. This combination works very well and costs much less than a complete replacement.
- Does the ceiling height allow for a console? A floor-mounted console unit blows warm air at foot level. For a basement that is used extensively in winter, it is often the best technical choice.
The FreeMatch range allows different types of indoor units to be combined with the same outdoor unit: a wall-mounted unit upstairs and a floor console in the basement, for example. We are not limited to installing the same appliance twice.
On this Chambly project, the wall-mounted unit met the client's actual needs, with the baseboard heater providing supplemental heat. The choice was made after discussion, not by default.
The second function, often the most useful: dehumidification
A Quebec basement is humid in summer. The foundation is in contact with cool ground, water vapor from the warm air condenses there, and the characteristic basement odor sets in.
A wall-mounted heat pump in cooling or dehumidification mode handles this problem much better than a portable dehumidifier, for three reasons:
- It drains water continuously through the drain, without a tank to empty.
- It cools and dehumidifies simultaneously, whereas a portable dehumidifier warms the room while operating.
- With an inverter compressor that modulates at low speed for long periods, air passes over a cold coil longer, which extracts more moisture for the same amount of cooling.
This is where sizing matters most. An oversized system cools quickly, reaches the setpoint, shuts off—and doesn't have time to dehumidify. The basement becomes cold and clammy: the worst of both worlds. Proper sizing, or even slightly conservative sizing, provides much better comfort.
Coordination with the existing ventilation system
The visible grille in the basement ceiling belongs to the home's ventilation system. This detail deserves attention because it is systematically overlooked.
A heat pump does not ventilate. It recirculates the room air, treats it, and sends it back. It does not bring in fresh outdoor air or remove any pollutants.
A finished, well-insulated basement becomes airtight. Without a supply of fresh air, moisture produced by occupants, the laundry room, and the shower accumulates, and air quality deteriorates.
We therefore systematically check:
- The presence and operation of an air exchanger or mechanical ventilation system.
- The position of the supply and exhaust grilles in relation to the indoor unit, to prevent a cold fresh-air stream from disrupting the appliance's temperature sensor.
- The overall balance when the basement's use changes.
A heat pump and an air exchanger complement each other; they are never interchangeable.
The installed equipment
The selected outdoor unit is the GREE FreeMatch R32, model GWHD(24)ND6MO, powering two indoor units.
What makes it suitable for this type of project:
- Rated capacity of 7,030 W (24,000 BTU/h), for both heating and cooling.
- Modulation from 7,500 to 31,400 BTU/h with the G10 inverter compressor — essential for dehumidification at low speed.
- Heating certified down to -30 °C.
- SEER2 21 / HSPF2 10 / EER2 12, ENERGY STAR certified.
- R32 refrigerant (A2L) with an integrated leak detection sensor.
- Indoor units powered by the outdoor unit — decisive in renovations, since only one dedicated circuit is required.
- Smart defrost, self-diagnostics, automatic voltage adjustment.
- Standard 10-year warranty.
The A2L requirement in the basement
The R32 refrigerant is classified as mildly flammable. This requires a minimum room volume for each indoor unit, depending on the system charge.
A basement divided into small enclosed rooms—bedroom, office, or playroom—deserves careful review at the design stage. Installing a high-capacity head in a small enclosed space may conflict with the manufacturer's requirements.
We validate this calculation before proposing a configuration, in Chambly as well as Longueuil, Montréal, Laval, on the North Shore, or elsewhere on the South Shore.
What the Client Actually Gained
- A usable basement twelve months a year, rather than a space avoided in winter and that smells damp in summer.
- Cooling on the main floor through the second head, without a window unit.
- Reduced reliance on electric baseboard heaters, which are kept as backup for cold snaps.
- No visible conduit, thanks to coordination with the finishing work.
- Two separately controlled zones, each with its own setpoint.
Eligibility for Financial Assistance
GREE documentation indicates that these systems are eligible for local rebates, and ENERGY STAR certification is among the common criteria for Quebec energy-efficiency programs.
Actual eligibility depends on your situation: the heating source being replaced, the type of building, and the program in effect when the work is done. We validate the application before the work and provide the installation documentation required for applications.
Maintenance: What Changes in the Basement
In addition to the usual steps — cleaning filters every 4 to 6 weeks, annual HVAC maintenance, and clearing snow from the outdoor unit —, a head installed in the basement requires two specific checks:
- The condensate pump, if the system has one. Annual tank cleaning prevents blockages and overflows.
- Accelerated filter fouling. A basement often houses the laundry area: textile fibers clog the filters much faster than they do upstairs. A clogged filter causes the evaporator to ice up and overloads the compressor.
Are you finishing your basement in Chambly, the Richelieu Valley, or elsewhere in Montérégie? Contact us before the drywall is installed. This is when installing a heat pump costs the least and delivers the best results.