Installation of a GREE FLEXX R32 ULTRA central heat pump (by Dettson) in a recessed corner in Sainte-Victoire-de-Sorel, Pierre-De Saurel RCM

A downspout, a wall vent, and a window well: the wall was already occupied before we arrived

In catalog photos, an outdoor unit is always alone in the middle of an immaculate lawn. In real life, it arrives last on a wall that already contains a downspout, an exhaust vent, a window well, an outdoor faucet, an electrical outlet, and sometimes the electric meter.

That was exactly the situation in Sainte-Victoire-de-Sorel, an agricultural municipality in the Pierre-De Saurel RCM. A bungalow with a basement, vinyl siding, a brick wall return, and only one viable location for the outdoor unit: the inside corner formed by the two walls, precisely where three elements that could not be moved were already located.

We installed a GREE FLEXX R32 ULTRA central heat pump, distributed in Quebec by Dettson, on supports anchored to the foundation. The actual work began well before the unit was delivered: it began with surveying this wall.

The survey: four elements to work around

Before securing anything in place, we inventoried what was already occupying the area:

1. A downspout with a discharge elbow at the end of the brick wall.
2. A low wall exhaust vent, about two feet from the proposed coil location.
3. A basement window well at ground level, just to the right.
4. A mature tree whose shade covered the façade—and therefore brought leaves and seeds every fall.

Each of these elements affected the unit's final position. None was ignored. Here's why.

Selected equipment: 34,000 BTU/h

The modulation from 18,000 to 37,000 BTU/h is the most useful information in this table for a homeowner. It means the unit can operate at half capacity for hours instead of repeatedly starting and stopping. This prolonged low-speed operation produces the most stable comfort, the lowest sound level, and the most effective dehumidification in July.

The inside corner: two walls that send everything back

A corner formed by two perpendicular walls is the most challenging location for an outdoor unit, and it is also the one homeowners propose most often because it is discreet.

Recirculation

The unit draws air in through the coil, at the rear and on the sides, and discharges it through the fan toward the front. In a corner, some of the discharged air bounces off the perpendicular wall and returns toward the air intake.

In cooling mode, the unit then draws in its own hot air again: condensing pressure rises and efficiency drops. In heating mode, it draws in its own cold air again: available capacity decreases precisely when you need it most, and defrost cycles become more frequent.

The chosen orientation places the discharge toward the open area of the yard, opposite the return wall. The coil, meanwhile, retains the clearances required by the manufacturer on its intake sides. It is this trade-off—never a rule-of-thumb compromise—that determines the final position.

Asymmetrical clearances

A common mistake is to assume that a unit requires the same clearance on every side. That is not the case: the discharge side, intake sides, and service side have distinct requirements.

The service side, in particular, is the one most readily sacrificed to gain a few centimetres. This is a poor calculation. A technician who cannot open the control panel without dismantling the unit will bill that additional time at every service call for fifteen years.

Sound reflection

Two hard surfaces meeting at a right angle concentrate sound rather than dispersing it. A unit rated at 61 dB(A) at high output will sound louder in a corner than in the middle of a yard.

In practice, modulation resolves much of the issue: the unit operates well below its maximum output for most of its running time. Nevertheless, we always confirm the required setbacks from property lines and the permitted noise levels with the municipality before determining the location, because these rules vary from one municipality to another in Montérégie.

The downspout: the litre per second we forget

A single-family home’s roof can concentrate hundreds of litres of water into one downspout during a storm. That water has to go somewhere, and “somewhere” cannot be your heat pump’s coil.

Two distinct situations arise:

• In summer, water sprayed from a poorly oriented discharge elbow splashes the coil, deposits soil and ground particles on it, and accelerates fouling of the fins.
• In winter, an overflowing or frozen gutter creates continuous runoff that solidifies at the base of the wall. An accumulation of ice rising up to the cabinet is the fastest way to put an appliance out of service.

In Sainte-Victoire-de-Sorel, the downspout discharge was directed away from the appliance, and the unit’s position was chosen outside the splash zone. Mounting it on supports, which raises the appliance off the ground, provides an additional margin: ground ice cannot reach the coil.

The exhaust wall outlet: the most underestimated of the three

This is the element we most often see neglected, and the one that causes the most puzzling service calls for the owner.

A wall outlet—dryer exhaust, a combustion-appliance termination, or the discharge from a ventilation system—expels air that is hot, moisture-laden, and sometimes full of lint.

Place a heat pump coil in the path of this exhaust, and you get:

• In winter, moisture settles directly on fins that are already below freezing. Frost forms much faster than it should, defrost cycles multiply, and heating performance collapses. The owner concludes that the appliance is defective, when it is doing exactly what it was designed to do.
• In every season, lint sticks to the fins and forms a felt-like layer that blocks heat exchange.
• In the case of a combustion-appliance termination, there is a safety issue that goes far beyond performance: the prescribed minimum clearances around these terminations must be respected, without exception or creative interpretation.

Our assessment therefore established the exact nature of this outlet and the applicable clearances before determining the appliance’s position. A heat pump installed two feet too far to the left on this wall would have operated perfectly in July and poorly in January—that is, during the season when it costs you the most.

The basement window: noise, clearance, and snow

A basement window raises three questions at once.

• Transmitted noise. A window is infinitely less insulating than a wall. An appliance placed in front of a basement window serving a bedroom will be heard.
• Keeping the window clear. A basement window can serve as an emergency exit. It must not be blocked.
• Snow accumulation. A window well retains snow and ice. Placing a coil right beside it exposes the coil to accumulation that melts and refreezes all winter.

The selected position leaves the basement window well completely unobstructed and directs the discharge away from the window.

The crushed-stone bed: the right ground treatment

Under the unit, the ground was finished with a crushed-stone bed rather than a solid slab or pavers. This is not an aesthetic choice.

• Drainage. A heat pump discharges several litres of water during each defrost cycle. On an impermeable surface, this water spreads out and freezes into a sheet of ice. In a stone bed, it percolates away.
• No splashing. The stone does not splash soil onto the coil when it rains, unlike bare ground or mulch.
• Weed control. A strip of stone limits vegetation that could grow up toward the air intake.

It's a detail costing a few hundred dollars that protects equipment worth several thousand.

Agricultural winds and powdery snow

Sainte-Victoire-de-Sorel is surrounded by large cultivated fields. In open agricultural terrain, winter winds carry fine, dry snow that behaves very differently from city snow.

This fine, windblown snow infiltrates even the smallest openings in a cabinet, accumulates inside, melts when the compressor starts, and refreezes when it stops. On a poorly oriented unit, the result is a block of ice inside the cabinet itself.

Two measures apply in an exposed area:

• Orient the main intake face away from the prevailing winter winds, which generally come from the northwest in this area.
• Install the unit with ground clearance, as the support-mount installation does here, so that a snowdrift on the ground cannot reach it.

The inside corner, however awkward it may be for airflow, does provide real shelter from blowing snow. This is the kind of trade-off that an on-site assessment can evaluate, but a phone quote will never see.

The tree

The shadow cast on the wall indicated a mature tree nearby. A tree means welcome shade over the coil in July—and leaves, samaras, and seeds in September.

We warned the owner that cleaning the coil in late fall would now be part of their routine, just like replacing the indoor filters. A coil clogged with a mat of leaves loses a significant portion of its capacity, and this loss develops gradually without ever triggering a fault code.

Three entry points to financial assistance, and the one that applies to you depends on your current heating system

This confusion costs homeowners on the South Shore and in Montérégie dearly every year. There is not one single program, but three distinct pathways.

LogisVert — this project's case

This is Hydro-Québec's residential program for purchasing an efficient heat pump: $50 per 1,000 BTU/h, or $120 per 1,000 BTU/h for a cold-climate-rated unit, calculated based on the certified capacity at −8°C of the installed AHRI combination. ENERGY STAR certification is mandatory for any installation completed since November 26, 2025, and the unit must provide at least 12,000 BTU/h of cooling capacity.

This is the applicable pathway for a central heat pump installed in a house, condominium, multiplex, or building with no more than 19 dwelling units.

The no-cost heat pump for low-income households

A completely separate and much less well-known pathway. It involves registering for the Éconologis program and provides access to a ENERGY STAR-certified wall-mounted heat pump designed for cold climates, at no cost, including equipment and installation.

Conditions to know before basing a project on it:

• The dwelling must be heated with electric baseboard heaters and must not already have a heat pump.
• The household must meet income thresholds based on household size.
• It must be the primary residence, with an electricity account in the participant's name.
• This is a wall-mounted heat pump, not a central system. It is therefore not the right pathway for a project like the one in Sainte-Victoire-de-Sorel.
• The 2026–2027 registration period has ended: Hydro-Québec is currently processing the applications received, with a gradual rollout by region.

If your home is heated with electric baseboard heaters and you believe you meet the criteria, the process starts with Éconologis, not with a contractor.

Solutions efficaces — for businesses

A commercial building or a building owned by a company falls under a different Hydro-Québec program, Solutions efficaces, with one component for small businesses and another for medium-sized and large businesses. The support structure and process differ from those for residential properties.

We determine the applicable pathway at the time of submission, before equipment is ordered. This is the only way to prevent an application from being rejected for a reason that could have been addressed in advance.

Six mistakes specific to already-occupied walls

1. Installing the unit in the airflow from an exhaust wall vent.
2. Ignoring the required clearances around the termination of a combustion appliance.
3. Placing the coil in the splash zone of a downspout.
4. Blocking a basement window, which may serve as an emergency exit.
5. Treating the clearances as identical on all four sides of the unit.
6. Installing the unit on a solid slab without planning where the defrost water will go in February.

Where we work

Our teams serve the RMC of Pierre-De Saurel — Sainte-Victoire-de-Sorel, Sorel-Tracy, Sainte-Anne-de-Sorel, Saint-Robert, Saint-Aimé, Yamaska, Saint-Ours — and all of Montérégie, as far as Saint-Hyacinthe, Contrecœur, and Varennes.

We carry out the same installations throughout the South Shore — Longueuil, Boucherville, Brossard, Saint-Hubert — in Montreal neighborhoods where side walls are even more crowded than in the countryside, in Laval, and on the North Shore, from Terrebonne to Saint-Jérôme.

The homeowner in Sainte-Victoire-de-Sorel had received a quote from another company before contacting us, prepared without a site visit. The proposed location would have placed the unit directly in front of the wall vent. After commissioning, he told us: “No one else had come to look at the wall.”

Let's move forward with your project

If your wall is already occupied, if your only available location is a corner, or if you simply want to know where a central heat pump can actually go in your home, the answer cannot be given over the phone.

At AirGreen, every HVAC installation project begins with an on-site assessment: an inventory of the existing elements on the wall, room-by-room load calculations, verification of clearances and municipal regulations, electrical load calculations, and preparation of the financial assistance application. Contact us about your project in Sainte-Victoire-de-Sorel, in the RMC of Pierre-De Saurel, in Montérégie, on the South Shore, in Montreal, in Laval, in Longueuil, or on the North Shore.