Installation of a GREE FreeMatch R32 GWHD(24)ND6MO two-head wall-mounted heat pump in Sainte-Madeleine

Installing a compressor on a building balcony: the problem is not the weight, but the air

At Sainte-Madeleine, in the Maskoutains RCM, we installed a two-head GREE FreeMatch R32 wall-mounted heat pump whose outdoor unit had to be installed on a building terrace: a concrete parapet on one side, brick walls on two others, membrane roofing on the ground, and an apartment window less than one meter away.

This type of location comes up repeatedly in heat pump projects in multi-unit buildings and condominiums, in Montreal, Laval, Longueuil, and the surrounding suburbs. Owners see available space there. We see three constraints that, if mishandled, ruin the unit's performance or damage the building.

The system: GREE FreeMatch R32, GWHD(24)ND6MO compressor

Technical data sheet

Two figures carry significant weight in a building setting. The 2,236 cfm airflow: this is the volume the unit must be able to draw in and discharge freely, and it is precisely what an enclosed space compromises. And the 58 dB(A): measured at maximum output, at close range. At low modulation—that is, most of the time—the unit is significantly quieter, but a neighbor whose window faces the fan from three meters away will judge the installation by its worst nights, not its average.

The real risk of a recessed location: air recirculation

A heat pump outdoor unit draws air in through the back and sides of the coil and discharges it through the front, through the fan. In cooling mode, the discharged air is hot. In heating mode, it is cold.

Place this unit in a recess closed on three sides, and the discharged air has nowhere to go. It circulates, returns toward the intake, and the unit starts treating its own exhaust air again. This is recirculation, and its effects are measurable:

• In summer, the incoming-air temperature rises. Discharge pressure increases. Efficiency drops, the unit consumes more power, and the SEER2 of 21 becomes a laboratory figure unrelated to the reality of the home.
• In winter, the intake air is cooled by the discharge air. The coil frosts more quickly. Defrost cycles multiply, each consuming energy and interrupting the heating.
• In the long term, the compressor operates outside its design range. Its lifespan decreases.

How we addressed it in Sainte-Madeleine

1. Discharge directed toward the only open side. The unit was positioned so that the fan blows toward the clearance, never toward the parapet or brick.
2. Rear and side clearances verified with a tape measure, against the GREE installation manual values—not “by eye.” These clearances are not comfort recommendations; they are performance requirements.
3. Verification of the discharged-air path. Discharge directed straight at a parapet one meter away returns toward the unit, even if the side clearance is compliant. We look at where the air goes, not just where it exits.
4. No future obstructions allowed. We tell the customer, and we write it in the report: no flower box, storage unit, or decorative screen may be added around the unit. This is the number-one cause of efficiency loss in the years following an installation.

When a location does not allow the required clearances to be respected, we refuse to install the unit there. A unit that operates poorly from its first summer is not a compromise; it is a problem we will have to resolve at our own expense.

The waterproofing membrane: do not drill, do not load

The floor of this terrace is covered with a waterproofing membrane. Beneath it is a living space or parking area. Drilling through this membrane to anchor a support, or placing a 51 kg compressor on four point supports, is essentially scheduling a leak.

Our method:

• Elevated aluminum support, visible in the photo, that completely lifts the unit off the membrane surface.
• Load distribution across pads or sleepers that spread the weight rather than concentrating it.
• No fasteners penetrating the membrane. Lateral support is provided by anchoring to the wall above the waterproofing line, or by ballast, never by drilling into the floor.
• Clearance beneath the unit so that defrost water flows toward the terrace drain and does not freeze against the frame.

This last point deserves emphasis: on a balcony, defrost water must reach the existing drain. If it stagnates, it freezes, and the ice exerts pressure on the membrane as it expands. We check the actual slope of the surface before fixing the location.

What Condominium Associations and Property Managers Need to Know

In a multi-unit building, an HVAC installation never concerns just one occupant.

Prior Authorization

The façade, parapet, membrane, and often the balcony itself are common elements. An installation carried out without the written consent of the condominium association or owner exposes the occupant to a removal order at their expense. We systematically request this authorization before ordering the equipment, and we provide the association with the unit's technical data sheet, dimensions, weight, and sound level to support the request.

Electrical Power Supply

The GWHD(24) requires a dedicated 208/230 V circuit protected by 25 A, with a disconnect switch within sight. In a multi-unit building, this circuit must run from the panel of the served unit, never from a shared circuit. Charging its air conditioning to all the co-owners is a guaranteed source of conflict.

Noise and Neighbors

We position the unit with neighboring windows in mind, not just the customer's. When space is tight, the unit's quiet operating mode is enabled for nighttime operation during commissioning.

A2L Refrigerant

R32 is classified as A2L: mildly toxic and slightly flammable. In a multi-unit building, this requires sizing the charge according to the volume of the rooms served by each head, a calculation we document in the file. The A2L leak detection sensor supplied with the system is checked and recorded in the commissioning report, which is provided to both the occupant and the property manager.

Errors we regularly correct in multi-unit buildings

• Compressor pressed against the rear wall. The intake clearance is restricted. The unit operates, the customer sees nothing, and the summer electricity bill never drops as much as promised.
• Support placed flat on the membrane. No clearance, standing water, ice, or leaks two or three winters later.
• Condensate discharged over the parapet. The water falls onto the balcony below. That leads to a complaint, followed by a formal notice.
• Refrigerant charge not adjusted. In a building, piping runs are long. Beyond the 30 m precharged length, adding 20 g/m is mandatory, and the 15 m height difference must be respected to ensure oil returns to the compressor.
• No documentation left with the building. Occupants change, and property managers change. The AHRI sheet, evacuation report, final charge, and HVAC maintenance schedule must be kept in the building's records.

Performance and financial assistance

The GWHD(24)ND6MO delivers a SEER2 of 21, an HSPF2 of 10, and a COP of 3.9, with heating capacity maintained down to -30 °C thanks to its ENERGY STAR Cold Climate designation. For a home heated with electric baseboards, partially replacing them with a heat pump of this efficiency significantly changes winter consumption, particularly during the shoulder seasons, when the inverter modulates below one-third of its nominal capacity.

The unit falls within the performance categories generally accepted by energy-efficiency programs offered in Quebec, including LogisVert. The criteria, amounts, and required documents vary according to the program, building type, and year: we validate each application when the quote is prepared and provide the AHRI certification numbers and proof of installation required for processing.

Our approach

On a building balcony, a successful installation is recognized by what it does not produce: no leaks beneath the membrane, no complaints from neighbors, no loss of capacity by the third summer, and no dispute with the condo association. This comes down to three checks carried out before drilling anything—the airflow path, the water drainage route, and written authorization.

AirGreen performs the load calculation, supplies and completely installs the HVAC system, provides the dedicated electrical connection, documented commissioning, and annual HVAC maintenance for your wall-mounted heat pump in residential properties, condominiums, and multi-unit buildings in Montreal, Laval, Longueuil, the North Shore, the South Shore, and Montérégie, including Sainte-Madeleine and the Saint-Hyacinthe area.

Contact our team for an assessment of your project.