Installation of a GREE FreeMatch R32 2-head heat pump (GWHD(36)ND6MO) in Rosemont–La Petite-Patrie, Montreal

A heat pump suspended above a window well: when the water chooses the location

On this Rosemont–La Petite-Patrie project, the longest question to resolve was not the brand, the capacity, or even the routing of the lines. It was where the water would go.

The outdoor unit had to be installed on the side wall of a home in the eastern part of the borough, in a narrow passage paved with concrete. The only technically suitable location was directly above a window well, the galvanized sheet-metal basin that protects the basement window and, by definition, rests against the foundation wall.

A wall-mounted unit that defrosts releases water. A window well, on the other hand, is designed to contain it. The two are not accidentally at odds: this is exactly the kind of detail no technical data sheet addresses, yet it determines whether the basement will still be dry five winters later.

Project at a glance

• Borough: Rosemont–La Petite-Patrie, eastern sector, postwar single-family home with a finished basement
• Equipment: GREE FreeMatch R32 multi-zone wall-mounted heat pump, GWHD(36)ND6MO outdoor unit on wall brackets
• Zones: two wall-mounted heads — 24,000 BTU/h in the open-concept ground floor area (living room, dining room, kitchen) and 9,000 BTU/h in the primary bedroom upstairs
• Installed capacity: 33,000 BTU/h, or 92% of the compressor's nominal capacity
• Line lengths: approximately 8 m and 16 m, 24 m total, well below the 40 m factory charge
• Existing heating: retained electric baseboards, no air-duct network
• AHRI codes: 214931589 (ductless), 214931595 (ducted), 214931599 (mixed)

The product side, handled quickly and honestly

The selection arguments for a FreeMatch two-zone system have already been covered in depth in this series, and we will not repeat them here: the third port and heating reserve are discussed in our Beaconsfield article; reading the “min. – max.” line rather than the “nominal” line in the Dorval article; the rule that a single indoor unit should never equal the entire compressor capacity in the Kirkland article; line length as a selection criterion in the Dollard-des-Ormeaux article; the difference between the factory charge (a cost) and the maximum total line length (a firm limit) in the Côte-des-Neiges–Notre-Dame-de-Grâce article; the increase from 15 m to 25 m in elevation difference in the Pierrefonds-Roxboro article; sizing for the heating peak when there is no supplemental heat in the Pointe-Claire article; and load calculation as opposed to a square-footage ratio in the Rivière-des-Prairies–Pointe-aux-Trembles article. The behavior of a large wall-mounted indoor unit as a physical object—unobstructed wall space, anchoring, reach, and airflow noise—is also covered in the latter article.

What belongs specifically to this project comes down to two points.

First finding: it was the larger indoor unit that determined the compressor. With a 24,000 BTU/h indoor unit on the ground floor and a second zone, 33,000 BTU/h is required when both call simultaneously. The GWHD(30)ND6MO tops out at 34,100 BTU/h of modulated cooling: the margin would be 3%, which amounts to nothing once real-world conditions are taken into account. The GWHD(36)ND6MO delivers 40,900 BTU/h of modulated cooling and 51,180 BTU/h of modulated heating. It was not the size of the house that moved the selection up one model; it was the capacity required by a single room.

Second finding, and this is the acknowledged flaw in this configuration: the GWHD(36)'s modulation floor is 2,600 W, or approximately 8,870 BTU/h. The bedroom unit is rated at 9,000. The system floor and the small unit are practically the same figure—the tightest coincidence we have published in this series. In practical terms, this zone cannot go below what the entire system can produce at minimum: on its own, in mild weather, it will operate in short cycles. We say this before signing, not afterward. The mechanism is explained in our article on Saint-Chrysostome, the neighboring case involving a 9,000 unit on an 8,190 floor in Montréal-Est, and the recommended approach—operate the small zone together with the large one rather than on its own—in those on Saint-Urbain-Premier and Côte Saint-Luc. The configuration of the large unit so that it modulates down and does not impose its operating rate is covered in the one on Kirkland.

A customer who requires a perfectly modulated bedroom in every season needs a larger indoor unit or a separate system. This is a quotation sentence, not an after-sales service sentence.

GWHD(36)ND6MO technical data sheet

The unit is ENERGY STAR certified and includes smart defrost, automatic voltage adaptation, self-diagnostics, and an A2L leak-detection sensor. The indoor units are powered by the outdoor unit.

Defrost water is winter water, and that changes everything.

Two water circuits must be separated because they operate in different seasons and follow different paths.

The indoor-unit condensate pan produces water in summer, when the indoor coil is cold and ambient air condenses on it. That drain is adjusted with a continuous slope and checked by pouring in water.

The outdoor unit, on the other hand, produces its water in winter. In heating mode, the outdoor coil drops below the dew point and then below freezing, frost forms on it, and the unit periodically initiates a defrost cycle that releases this water all at once. A single cycle is not much. An entire winter of cycles concentrated in the same place, on ground that freezes and thaws, is something else entirely. And because the unit is here suspended on wall brackets, the water does not trickle along a base: it falls from above, at one single point, always the same.

That is precisely what gutters, downspouts, and the slope of the ground are there to prevent around a foundation.

A basement window well is a basin resting against the foundation

A window well is not decorative trim. It is a basin set into the ground against the foundation wall, whose bottom very often constitutes the lowest point of the entire side passage. It is designed to hold back soil and let in light, not to drain a steady flow.

Three consequences to verify before attaching any support:

1. Whatever falls into a window well stays there longer than elsewhere. In January, the ground is frozen: the water cannot percolate; it accumulates and turns to ice. A window well filled with ice exerts pressure on the window frame and keeps water in constant contact with the top of the foundation.
2. When a window well has drainage, it leads to the foundation drain. Deliberately adding a heat pump's defrost water to it six months a year means burdening a buried system that cannot be seen or inspected, for no benefit.
3. A window well is a trap for leaves and snow. It fills up on its own in the fall, and snow pushed onto the walkway ends up in it. A unit that blows directly above it accelerates the process instead of slowing it down.

The important point: none of these situations triggers an error code. The unit operates perfectly while the water does its work. The warning sign appears elsewhere, later, and no one connects it to the heat pump.

A basement window is still a window—and sometimes an exit

This is the other half of the issue, and it often escapes entrepreneurs who look at the wall without looking at what lies beneath it.

A window well exists because there is a window. That window provides light, ventilation, and, when the basement contains a bedroom, an exit. In Quebec, a basement bedroom must have an opening that allows evacuation in an emergency; the exact requirements fall under the Building Code and municipal regulations, and they are interpreted by a building professional or the competent authority, not by the HVAC contractor. We therefore provide no specific dimensions here.

What we apply, however, is a simple, non-negotiable internal rule: no appliance, support, or duct may reduce the opening of a window that must remain usable. This applies to the sash, the clear space inside the window well, the escape ladder when there is one, and emergency-service access from the side passage. It is also true for a much more ordinary use: a basement window that can no longer be opened because an appliance is in the way is a room we stop ventilating.

On this project, the height of the supports and the discharge-air axis were determined based on the window, then checked again with the unit in place and the sash open.

What we resolved before drilling

• Offset location. The appliance partially overhangs the window well, but its water discharge point has been moved toward the concrete slab rather than toward the basin. We move the appliance a few dozen centimeters; we do not move the water afterward.
• A drainage bed beneath the discharge point, outside the traffic path and away from the foundation. Defrost ice on a surface people walk on is addressed in our Vaudreuil-sur-le-Lac and Les Cèdres articles; we will not revisit it here.
• The actual slope of the passage measured, taking into account that snow conceals it all winter.
• Anchoring into a genuine structural element, never into the cladding. The substrates — poured concrete, hollow block, stucco, vinyl siding — and the anti-vibration pads visible beneath the chassis are covered in our Ahuntsic-Cartierville and Vaudreuil-sur-le-Lac articles.
• Clearances measured before installation, at both the front and the back. An appliance wedged into a narrow passage re-ingests its own discharged air: condensing pressure rises in cooling mode, defrost cycles multiply in heating mode, and nothing turns on anywhere. The full mechanism is explained in our Ahuntsic-Cartierville article.
• What we do not promise. Two heads serve two spaces, not an entire house. The finished basement is not air-conditioned by this installation, closed doors cancel everything out, and the baseboard heaters remain in service everywhere else — see our Baie-D'Urfé and Saint-Cyprien-de-Napierville articles.

The gray box on the wall: the outdoor disconnect, the component no one looks at

In the photo from this job, to the right of the equipment, there is a gray object the size of a lunch box. This is the outdoor disconnect, connected to the unit by a flexible cable and running alongside the insulated refrigerant line set that passes through the wall at the same location.

This is not an accessory. It is the component that determines the quality of all maintenance over the next fifteen years, and it deserves its own section. The general installation of outdoor electrical equipment is covered in our Côte Saint-Luc article, and the specific case of a disconnect mounted on an equipment support because no wall was available is covered in the Pointe-Claire article; what follows is the component itself.

A breaker protects a circuit; a disconnect isolates equipment

These are two distinct functions, and they are constantly confused.

The breaker in the panel protects the circuit against overcurrents. The disconnect installed near the outdoor unit serves to isolate the equipment, in plain sight, so that the person working on it knows — and can see — that nothing can re-energize it while their hands are in the electrical box or near the fan.

There is a third function, the one we discuss with the client during commissioning: it is the only device that allows the owner to safely shut off power to the heat pump before the annual rinsing of the outdoor coil, without going down to the panel and without hoping that no one will reset the breaker in the meantime. The cleaning method itself — what is permitted and what destroys a coil in ten minutes — is published in our Pierrefonds-Roxboro article.

A trivial yet decisive detail: an unidentified box is a box no one uses. The equipment served and the circuit number are recorded in the closeout documentation and given to the client along with the rest.

With or without fuses: 30 A MCA, 45 A MOCP

The GWHD(36)ND6MO specifications sheet lists two electrical values that do not serve the same purpose.

• The 30 A MCA, the minimum circuit ampacity, sets the minimum conductor size.
• The 45 A MOCP, the maximum overcurrent protection, sets the value not to be exceeded for the protective device.

These are not commercial suggestions: they are the manufacturer's instructions. Increasing the circuit breaker rating “to prevent tripping” defeats exactly the specified protection. Depending on the configuration selected, the disconnect switch may be fused or non-fused, and when it is fused, the type and rating of the fuses are not a matter of free choice either.

This entire aspect belongs to the master electrician, who performs the connection and load calculation in accordance with the Code. Our contribution is to provide the correct nameplate values before anyone pulls a wire—and to refuse quotes where the electrical requirements are “to be confirmed.” The ten-point quote comparison checklist in our Saint-Chrysostome article covers this trap. The impact of the protective device rating on an older panel is covered in those on Saint-Édouard and Napierville.

Five ways to kill an outdoor enclosure

A disconnect switch is an electrical enclosure installed outdoors, one metre above the ground, in a climate alternating between driving rain, blowing snow, and freeze-thaw cycles. What destroys it is never the electricity: it is water.

1. Unused knockouts left open. Every unsealed opening is an entry point for water and insects, directly above the contacts.
2. The absence of a drip loop on the flexible cable. If the conductor enters the enclosure from a higher point, water running along the jacket follows the cable and enters with it. A simple loop below the entry point solves the problem once and for all.
3. A height calculated based on the day's snow rather than the year's snow. A disconnect switch buried in February is inaccessible precisely in the month it is needed.
4. A cover that no longer closes. Screws lost after a service visit, a forced hinge, a door left ajar: an enclosure that does not close is no longer an outdoor enclosure—it is a water inlet.
5. An enclosure type not verified for outdoor use. This must be verified; it cannot be assumed.

The sequence is always the same, and it is insidious: corroded contacts heat up, a heating terminal loosens, and the failure appears as a finicky appliance—a failed start, an intermittent restart—rather than an electrical fault. This is why tightening the terminals is part of the annual maintenance inspection, as we explain in our Pierrefonds-Roxboro article.

What a disconnect switch should not be used for

Rarely explained yet common: a disconnect switch is not a general-purpose switch.

Turning the unit off at the disconnect instead of using the remote or wall control deprives the system of its standby functions—crankcase heater operation, restart delay, and an orderly shutdown sequence—and repeatedly restarting it at the electrical box is harder on the electronics than a normal extended shutdown. The same is true after a power outage: do not repeatedly flip the disconnect or circuit breaker to “see if it starts again.” Our Havelock and Saint-Anicet articles address post-outage behavior and operation during extended absences.

The disconnect has one purpose: to de-energize the unit before anyone reaches near it. It does not replace surge protection, a properly sized circuit, or grounding installed according to code.

The wall penetration, thirty centimetres away

In the photo, two passages go through the same wall a few centimetres apart: the electrical supply and the set of insulated refrigerant lines, along with the interconnection wire and the drain.

What we apply:

• The penetrations are grouped and aligned. On horizontal siding, two aligned penetrations can be sealed and repaired cleanly; three scattered penetrations can never be made right.
• Every penetration is sealed, with a drip edge where the orientation requires it. The technique is covered in our Côte Saint-Luc article.
• The copper lines and drain never rest on the electrical box or the flexible cable. An electrical box is not a pipe support, any more than a service mast is.
• The insulation on both lines remains continuous, without interruption at the wall penetration. On an exposed outdoor section in direct sunlight, a continuous rigid conduit is specified: insulation degradation caused by ultraviolet rays is addressed in our Dollard-des-Ormeaux article.
• The slack left in the lines—enough to pull the unit away from the wall without cutting anything—has its own rationale, explained in our Pointe-Claire article.

One circuit, one disconnect, the entire system

On a FreeMatch system, the indoor units are powered by the outdoor unit. There is therefore not one circuit per head: there is one circuit, one panel, and one disconnect for the entire system.

Two practical consequences follow. The first is an installation advantage: only one power supply needs to be run, and only one breaker is used at the panel, which is significant in a house where the panel is already occupied by baseboard heaters, a water heater, and a dryer. The second is an operating constraint: this single disconnect switch cuts power to the entire system, including both heads. You cannot de-energize one zone to maintain another, so this must be planned. In a multi-unit building, this same feature also determines who pays for the electricity—the subject is covered in our LaSalle and Lachine articles.

Mistakes to avoid with this type of installation

• Choose the outdoor location for installation convenience rather than for the water's path. This is the leading cause of damage wrongly attributed to the unit.
• Hang a unit above a window well, basement entrance, light well, or exterior staircase without redirecting the water's discharge point.
• Reduce, even partially, the opening of a basement window or the clearance around its window well.
• Pair a small head with a large compressor without disclosing it. Here, 9,000 BTU/h versus a system minimum of 8,870: it is workable, it is explained, it is not ideal, and the customer must learn about it before signing.
• Oversize the breaker beyond the 45 A MOCP to stop nuisance trips caused by an issue elsewhere.
• Treat the disconnect switch as an afterthought. If it is poorly placed, improperly closed, or buried, it turns a thirty-minute maintenance visit into a half-day job.
• Use the disconnect switch as a daily switch.
• Remove the electric baseboards as early as the first year.
• Cover the unit for winter. A heat pump operates in winter; a fully enclosed cover traps moisture and prevents drying after defrosting.

Maintenance: what the owner is responsible for and what we are responsible for

• Every 4 to 8 weeks during the intensive season: rinse the indoor filters of both heads.
• In spring: clear around the outdoor unit, clean the window well, rinse the coil with a hose at normal pressure, with power cut off at the disconnect switch, and check that water is properly draining away from the unit's base.
• In autumn: run in fan-only mode for twenty to thirty minutes after the last cooling use, then clear the area where snow will be pushed.
• Once a year: a complete technical inspection, ideally in May or September. What a proper inspection measures and records—voltage, current compared with the 19.6 A RLA, terminal tightening, the condition of both coils, drain-flow testing, and the history of recorded codes—is detailed in our Pierrefonds-Roxboro article.

Grants and eligibility

A multi-zone wall-mounted heat pump installed in a Montreal residence may qualify for financial assistance programs, notably Hydro-Québec’s LogisVert and Rénoclimat. The conditions, amounts, and required documents change periodically, so we verify eligibility when opening the file rather than announcing it in advance. The Chauffez vert program does not apply here, since it targets the replacement of an oil- or propane-fired heating system and this house was heated with electricity.

An administrative point few contractors explain: the declared performance belongs to a certified AHRI combination, not to an individual unit. That is why each FreeMatch model has three codes depending on the configuration. The code recorded in the file must match what was actually installed; otherwise, an application may be rejected for a purely administrative reason. The complete reasoning can be found in our Saint-Anicet article.

Rosemont–La Petite-Patrie: a borough where lateral space is measured in centimetres

The borough has 141,813 residents spread over 15.9 km². This density is not a decorative statistic: it explains why, here, outdoor-unit placement comes down to a passage less than two metres wide, between a foundation and a fence, and why the clearance around a window well becomes the day’s real technical issue.

The area was built around a single employer. Canadian Pacific’s Angus Shops opened in 1904 with 3,000 workers, quickly grew to 5,000, and reached as many as 12,000 during the Second World War; the neighbourhood lived by the rhythm of their sirens for nearly a century, until the closure was announced in 1991 and the site’s redevelopment began in 1998 with Technopôle Angus. To the south, the former villages of Côte-de-la-Visitation (1870) and Côte-Saint-Louis (1878) were annexed to Montreal in 1910 and formed the Saint-Édouard neighbourhood—the very one Claude Jasmin described in his 1972 novel, whose title eventually gave its official name to La Petite-Patrie when the borough was created in 1989.

This history has left a very distinctive housing stock: flat-roofed duplexes and triplexes in the western part, postwar single-family homes farther east, finished basements almost everywhere, basement windows and window wells on nearly every side façade, and lanes that often dictate site access. We install in Rosemont, La Petite-Patrie, and neighboring boroughs, as well as throughout Montreal, Laval, Longueuil, the North Shore, and the South Shore.

Why entrust this type of project to AirGreen

At AirGreen, we approach this work with one fixed idea: what distinguishes two installations that are identical on paper are the decisions made before the first hole is drilled. On this Rosemont project, the brand and model accounted for one hour of discussion; the location above the window well, the disconnect height, the water drainage point, and the window clearance represent fifteen years of peace of mind—or fifteen years of annoyances.

We are an RBQ-licensed company specializing in residential and commercial HVAC installation, and we provide every customer with a complete project closeout file: models and serial numbers for each room, the AHRI code for the combination actually installed, developed line lengths and weighed refrigerant charge, commissioning readings, circuit number, and a one-page user guide for each zone.

Are you considering a two-zone wall-mounted heat pump, an equipment replacement, or a comparative quote? Write to us at sales@airgreen.ca or call (514) 316-2973. We come to your property for a technical assessment, measure everything that needs measuring, and provide a quote that specifies the models, capacities by room, planned line lengths, and what is included—including what we will not do.