Installation of a GREE FreeMatch R32 2-head wall-mounted heat pump (GWHD(42)ND6MO) in Westmount, Montreal agglomeration

A project where the permit was submitted before the model was ordered

On most of our projects, the sequence is the one clients expect: site visit, load calculation, model selection, installation date. At Westmount, we have made a habit of reversing the first two steps in the administrative schedule. The permit application is submitted before the order is placed, because the city reviews the building’s exterior appearance, and because a discretionary decision cannot be scheduled like a supplier delivery.

This project is a GREE FreeMatch R32 two-head wall-mounted heat pump installed on a GWHD(42)ND6MO in a 1920s house in upper Westmount, on the mountainside. The condenser is mounted on wall brackets on the rear wall of a vinyl-sided extension, above a parged foundation. The regulatory framework, rather than the load calculation, set the pace of this project from beginning to end.

The house, the two selected zones, and the areas the system does not serve

Detached house, original masonry on the front façade, newer rear vinyl-sided extension, parged foundation visible below the siding. Electric heating by baseboards, no air ducts, nothing to reuse from an existing system. Street-facing façade subject to architectural review, sloping backyard, planted garden with a wooden trellis: only one realistic location for an outdoor unit, and it was elevated on supports.

The selected plan consists of two zones, both with large volumes:

• 24,000 BTU/h on the ground floor, in the connected living room–dining room area, with high ceilings, solid masonry walls, and large southwest-facing windows.
• 24,000 BTU/h upstairs, in the family room created above the extension—a large, open volume overlooking the landing, whose envelope is the weakest in the house because it is partly above an unheated space.

Total installed: 48,000 BTU/h. What the system does not cover was written down before signing: the second-floor bedrooms are not served, nor is the basement, and the electric baseboards remain in place everywhere, including in the two air-conditioned rooms. They are not an admission of failure: they are the calculated supplementary heating, and they remain the freeze protection in the unserved areas.

Two comparable zones, occupied by the same people at the same times, are the least favorable scenario for a multizone system. We told the client this and write it into our quotations; the full demonstration is on our Vaudreuil-sur-le-Lac page, and we will not repeat it here.

The free port, and why it is worth more in Westmount than elsewhere

The entire product rationale for this range has already been published. The diversity factor belongs on our Saint-Denis-sur-Richelieu page, the interpretation of the “min. – max.” line on Dorval, the rule that a single head should never approach the capacity of the entire compressor on Kirkland, the 36k-versus-42k comparison on Havelock, and the observation that the 30k, 36k, and 42k share a single cabinet on Villeray. Only two considerations were specific to this project.

The first is arithmetic. With 48,000 BTU/h of installed heads, the GWHD(36)ND6MO tops out at 40,900 BTU/h at maximum modulated cooling: nothing remains when both zones call simultaneously, which is precisely the situation here. The GWHD(42)ND6MO reaches 44,300 BTU/h. We say this plainly: even with the 42k, the installed 48,000 BTU/h will never all be delivered simultaneously. The compressor modulates; it does not split. The installed capacity deliberately exceeds the machine's ceiling because each head must be able to serve its room on its own during the day, without ever operating at maximum fan speed.

The second consideration is administrative, and it is specific to Westmount. The GWHD(36) accepts 2 to 4 heads. The GWHD(42) accepts 2 to 5. Our Outremont page already explains why we leave ports free in an old building: it is not the equipment that is expensive, but the route. In Westmount, an additional, more significant factor comes into play: every future intervention on the building's exterior triggers a complete permit application process, including architectural review. Purchasing port capacity only once is not merely a technical convenience here; it is a procedural saving. The client is considering adding two bedrooms to the system within five years; the five-port compressor was selected for this reason.

The price of this option is almost negligible, as can be verified in the manufacturer's specifications: same cabinet, 79 kg versus 78.5 kg, same published sound level, same MCA, same MOCP, same R32 charge, and slightly higher efficiency (EER 3.81 and COP 3.9 versus 3.52 and 3.56). Between these two models, the only real differences are the purchase price, the allowable piping length, and the number of ports.

Here are only the data points that support the argument. The complete 42k column is published elsewhere on our site, and we are not reproducing it.

The two measured runs are 14 m and 22 m, for 36 m of total developed length, within the 50 m factory charge: not a gram of R32 was added. The elevation difference between the condenser and the upstairs head remains under 6 m, well below the 25 m limit.

An honest note about this unit: at 63 dB(A), it is the noisiest in the lineup, tied with the 36k. On an ordinary job site, this figure is a technical-spec detail. In Westmount, it is information the City requires in writing in the permit application.

Westmount is not a borough of Montreal

This is the most common initial mistake, and it costs weeks. Westmount is a linked city within the Montreal agglomeration, reconstituted on January 1, 2006, after the 2002 merger. It has its own urban planning department, its own bylaws, and its own municipal council. A quote prepared for a Montreal borough cannot be applied here, and the online procedures of the City of Montreal do not apply.

This is the exact opposite of the situation described on our Vimont, Laval page, where a single regulatory framework covers the entire Île Jésus and verification is done once for the whole territory. On the Island of Montreal, the agglomeration is a patchwork: an answer obtained in one borough is worthless in the neighboring linked city, and Westmount is the most demanding jurisdiction in the area.

The territory explains much of the system. Westmount covers approximately 4.04 km² on the southwest slope of Mount Royal, with 19,658 residents and 9,423 private dwellings in the 2021 census. Incorporated in 1874 as the Village of Côte-Saint-Antoine, it took the name Westmount in 1895, a direct reference to its position on the mountain. The housing stock grows as you climb toward Summit Circle; the lower part of the city consists of tightly packed semi-detached houses and townhouses, with side yards measured in tens of centimetres. In both areas, the outdoor unit’s location is constrained—down below by geometry, up above by scrutiny.

The documents the City requires before even opening the file

Our Huntingdon page established the general principle: you need to know where an outdoor unit may legally be installed before choosing the model. Westmount is the best-documented case we have encountered, and the distinction matters: here, it is not merely a matter of numerical setbacks, but of a discretionary review.

According to the City's documentation, the installation of a mechanical unit—heat pump, air conditioner, or cooling equipment—is governed by three separate by-laws:

• By-law 1303 on zoning;
• By-law 1305 concerning site planning and architectural integration plans (PIIAs), which applies as soon as the work affects the exterior of the building, except for the restoration or exact replacement of an original component;
• By-law 1387 on noise.

The PIIA changes the nature of the process. A project subject to it is not approved at the counter based on a compliance checklist: it is approved by the municipal council, according to architectural-integration criteria. This means a timeline that does not match the supplier's, and an outcome that is not guaranteed in advance.

The City also publishes a list of mandatory documents, and its checklist is explicit: if all documents marked with an asterisk have not been assembled, the application will not be opened at the counter. For a heat pump project, this notably includes:

1. a letter describing the nature of the work;
2. the owner's authorization if the application is submitted by a third party, and the authorization of the condominium association, where applicable;
3. a recent certificate of location, showing the property's current condition and boundaries;
4. a technical data sheet for the mechanical units, including their dimensions and noise level in decibels;
5. scaled drawings of the visual screen, when a screen is planned;
6. a detailed estimate of the cost of the work, before taxes;
7. for a heating or cooling unit installed on the roof of a semi-detached or row building, a description of a spring vibration-isolation suspension system.

Fee amounts, processing times, and numerical thresholds vary and should be verified with the City. We keep them up to date on our page City of Westmount: permits and regulations for heat pumps or air-conditioning equipment, which we give the client when providing the quote.

The decibel the manufacturer publishes without a measurement distance

This is the detail in the file that we find most revealing.

Westmount requires a technical data sheet stating the noise level in decibels. The GREE X610068B brochure, the official document for this product line, publishes 63 dB(A) for the GWHD(42)ND6MO—and specifies no measurement distance. We had already documented this shortcoming on our Huntingdon page, where we explain free-field attenuation and why a figure without a distance says nothing about what the neighbor hears. We will not repeat that explanation here.

What interests us here is the administrative consequence: a published value without a measurement reference enters a municipal file as is, where it will be read alongside thresholds that, in contrast, are defined at a specific point. Our code of practice, which we publish:

• we report the manufacturer’s figure exactly as published, identifying the source document and its revision;
• we never “correct” this figure downward in a permit application, even when the actual exposure at the property line is much lower;
• we instead attach a site-placement note describing the measures that reduce exposure to the surrounding properties: distance from the lot line, discharge direction, anti-vibration pads, absence of a reflective re-entrant corner, and night mode activated and recorded during commissioning—because this mode is shipped disabled from the factory, as we explain on our Dollard-des-Ormeaux page.

A contractor who enters a figure more flattering than the one on the manufacturer’s data sheet exposes the client to a regulatory problem the client has no way of anticipating.

The certificate of location—and why it blocks more applications than noise

The certificate of location is not a mere formality. It is required because the equipment’s position is assessed in relation to actual surveyed property boundaries, not the owner’s idea of where their property ends. In a side yard in Westmount, the gap between the fence and the lot line is sometimes thirty centimetres—that is, the entire project. We have seen several files come to an abrupt halt because the certificate on file predated the addition of an extension, a low wall, a shed, or landscaping.

Our rule: we request the certificate at the first visit, not when submitting the application. And no installation date is confirmed before the permit is issued. This sentence appears in our Westmount quotes; it protects the client far more than it protects us.

The visual screen: the only project element designed by the City and contradicted by the manufacturer

It is the part of the application that causes the most unpleasant surprises, and it deserves separate treatment. In the photo of this job site, a wooden lattice can be seen to the left of the condenser: this is exactly the type of structure in question, and exactly the type of structure that, if poorly designed, suffocates a new unit.

In Westmount, the screen is not a decision made on the morning of installation. It is a scaled drawing submitted with the permit application. And it brings together two requirements pulling in opposite directions:

• the City seeks the most complete screening possible from the public realm;
• the manufacturer requires minimum air clearances, asymmetric by face, on which the unit's capacity and longevity depend entirely.

Someone has to arbitrate between the two, and it is neither the urban planner nor the manufacturer. It is the contractor.

What a poorly designed screen actually does to the unit

The clearances for each face and the rule that the face without connections should preferably be placed against an obstacle belong on our Beaconsfield page; corner recirculation belongs on that of Ahuntsic-Cartierville. What follows is what we specifically see when a screen surrounds the unit.

1. The reduction of free intake area. In this enclosure, air enters from the rear and sides and exits through the front. A solid screen reduces the intake area before the fan has even started turning; the unit compensates by operating higher in its range, for longer, and harder.
2. The enclosure that breathes its own exhaust. Three closed sides and a closed top cause the discharged warm air to be drawn back in. In cooling mode, discharge pressure rises and capacity falls; in heating mode, intake temperature drops and defrost cycles become more frequent. No fault code says, “the unit is in a box.”
3. The snow trap. An opaque screen extending to the ground turns the equipment perimeter into a basin where blown snow, leaves, and road sand accumulate. Our rule: the screen stops above the design snow line, not at ground level.
4. Frost on the screen itself. This is the point no one anticipates. In winter, the defrost plume is moist air discharged over a short distance. In front of a solid, cold screen, this moisture settles and freezes; within a few weeks, the screen becomes a solid ice wall precisely where it was supposed to let air pass. An openwork structure, on the other hand, clears itself.

The materials, classified by what they do to the air

• Wood lattice: good open area at first, but it closes up as paint accumulates and becomes deformed. It ages poorly if no one monitors it.
• Spaced horizontal slats: the best compromise in our experience, provided the spacing is designed rather than improvised, and the slats are not oriented toward the equipment.
• Solid panel: avoid it on the intake faces and prohibit it on the discharge face. Use only as an offset side screen, at a real distance from the cabinet.
• Hedge or planting: elegant on the drawing, problematic over time, because a planting does not stay where it was placed. Our Côte-des-Neiges–Notre-Dame-de-Grâce page discusses the climbing plant that grows into the equipment, and our Ville-Marie page discusses the flower bed that rises and the clearance that disappears through neglect rather than by decision.

The five rules we impose on every screen

1. The screen is designed after the clearances, never the other way around. The manufacturer’s dimensions are placed first on the drawing; the structure is designed around them.
2. Nothing is attached to the equipment, its supports, or its anchors. A screen has its own structure, its own fasteners, and its own foundations. The anchors for the wall supports carry only the equipment.
3. The top remains open and the discharge face remains clear. This is non-negotiable, whatever effect is desired.
4. The screen can be removed without specialized tools. A panel screwed into decking is why the third-year maintenance is not carried out—and the coil-cleaning method described on our Pierrefonds-Roxboro page assumes that all three sides can be reached. The day the cabinet has to be lowered from its supports, the question will arise again: our Villeray page explains what handling equipment of this weight involves.
5. The filed drawing shows the equipment, not just the screen. We dimension the cabinet footprint, the required clearances, the structure’s open area, the removable panel, and the discharge axis. An elevation that shows only the fence is an elevation that has hidden the problem.

What we agreed on before drilling

The checklist was signed before the first hole:

1. no installation date confirmed before the permit is issued ;
2. single penetration through the vinyl addition, with drip edge and sealing; no passage through the original masonry of the facade;
3. screen with horizontal slats, drawn to scale with dimensioned clearances, open top, front panel removable by hand, ending above the snow line;
4. air discharge directed toward the garden, away from the property line and basement window;
5. outdoor disconnect switch labeled with the equipment and circuit number;
6. night mode activated and recorded during commissioning;
7. and the line “what we do not promise”: the second-floor bedrooms and the basement are not served by this system.

The mistakes we most often correct on this type of application

• Installing the equipment first and submitting the application afterward, hoping the work will be approved.
• Declaring an “estimated” sound level instead of the one listed on the manufacturer's data sheet.
• Submitting a twenty-year-old certificate of location that shows neither the addition nor the current fence.
• Having a landscaper build the screen without providing the manufacturer's clearance requirements.
• Screwing the screen onto the equipment supports to save on a separate structure.
• Covering the outdoor unit in winter, a practice we advise against everywhere and whose consequences are explained on our Ahuntsic-Cartierville page.

Multi-zone heat pump installation in Westmount and Greater Montreal

At AirGreen, we design, install, and maintain HVAC systems — wall-mounted heat pumps, multi-zone systems, air conditioners, furnaces, and air exchangers — in Westmount, throughout the island of Montreal, in Laval, Longueuil, on the North Shore, and on the South Shore. In an area like Westmount, our added value is not just about choosing the right model: it lies in submitting a complete permit application correctly the first time, designing a screen with the manufacturer's clearance requirements rather than against them, and confirming an installation date only once authorization is in hand.

For a two-head heat pump project or a larger multi-zone configuration, our teams conduct the technical assessment, prepare the required technical data sheet and plans, and assemble the application with you.