Installation of a GREE FreeMatch R32 2-head wall-mounted heat pump (GWHD(18)ND6MO) in Baie-D'Urfé, Montreal agglomeration

One line in the manufacturer's table determines whether your baseboard heaters remain connected

The installation completed in Baie-D'Urfé, in the West Island, is the second one we have documented in a 2-head configuration in the GREE FreeMatch R32 lineup. The complete overview of the GWHD(18)ND6MO — the smallest outdoor unit in the lineup, its modulation floor, its 10 m factory charge, and its installation on wall brackets — appears in our article about a project in Ahuntsic-Cartierville, and we will not repeat it here. This project addresses two things that overview does not cover: a technical-sheet anomaly that determines whether the electric baseboard heaters can be removed, and the decision that truly shapes a two-zone project: choosing the two rooms.

At AirGreen, we install multi-zone wall-mounted heat pumps in Montreal, Laval, Longueuil, on the North Shore and the South Shore, and two-head projects are where advice is most often copied from a four-head project, even though the constraints are reversed.

What we installed in Baie-D'Urfé

18,100 BTU/h: the heating reserve that does not exist

In the table from the X610068B commercial specification sheet, the heating capacity of the GWHD(18)ND6MO is listed as 5,275 W nominal (18,000 BTU/h), with a range of 2,140 to 5,305 W, or 7,300 to 18,100 BTU/h. The modulated maximum therefore exceeds the nominal value by 100 BTU/h — less than 1%.

The same table, read across the full range, gives the following:

On the other four models, this gap is usable reserve capacity: when the outdoor temperature drops and the home's demand rises, the compressor can exceed its rated capacity by 23% to 42%. On the 18,000 BTU/h model, this reserve is absent from the table.

We honestly point out the possibility of a typo in the data sheet: the 2,140 W minimum heating value is identical to the minimum cooling value, and we have not cross-referenced this line with an installation manual. Until the manufacturer contradicts it, however, it can only be read one way, and we prefer to treat it as true rather than sell backup capacity that appears nowhere.

What we write in the end-of-project report

• Electric baseboards are not disconnected. On this model more than any other in the range, they are the peak-load backup, not a relic. A contractor who promises to remove them from a GWHD(18) has not read this line of the table.
• The balance point is calculated and provided in writing before the order is placed. The mechanism—capacity falling while demand rises, and the intersection of the two curves—is detailed in our Franklin article.
• “Operates down to -30°C” describes an operating range, never a capacity. The FreeMatch data sheet publishes no low-temperature capacity data, neither at -8, -15, nor -25°C. This is the only question to ask any contractor: what is the capacity at -20°C, and where is my balance point?
• The baseboard setpoints are set 2 to 3°C below those of the heads; otherwise, they win the race and the customer concludes that the heat pump does not heat.

The modulation floor, viewed the other way

The GWHD(18)ND6MO goes down to 7,300 BTU/h, the lowest floor in the range—approximately 18% below the GWHD(42)ND6MO's 8,870 BTU/h. This is the main argument in favor of a small unit for two zones, and we developed it in our Ahuntsic-Cartierville article.

The supplementary reading, worth publishing because it nuances the first: proportionally, this small unit modulates less deeply. Its floor is approximately 41% of its rated capacity, compared with approximately 21% for the 42,000 BTU/h model. It therefore operates within a narrower range relative to itself. No consequence for a properly sized two-zone home; significant consequences if someone tried to add a third demand or an improperly assessed room.

What this project required in refrigerant

Our two developed lines measure approximately 7 m and 12 m, or 19 m in total: well within the 40 m limit, but 9 m beyond the 10 m factory charge. At 20 g/m, this represents 180 g of R32 added and weighed to a 900 g factory charge, or a 20% increase in the system charge.

This figure is not incidental: the minimum room area required because of R32's A2L classification and listed on the indoor unit's nameplate depends on the total charge, not the model. The smallest room must therefore be checked again after the final line routing, never at the quotation stage. The complete mechanism is explained in our Sainte-Martine article, and the values recorded from a nameplate in the Dundee article. On this project, the smallest room served is the bedroom; it governs, and the nameplate of the equipment actually delivered is authoritative.

The maximum elevation difference of 15 m imposed no constraints between a ground-level unit and an upstairs head.

The electrical circuit and outdoor-unit location

The GWHD(18)ND6MO is rated at MCA 14.5 A and MOCP 20 A, compared with 30 A / 45 A for the 36,000 and 42,000 BTU/h models, and the indoor units are powered by the outdoor unit: the two heads require no additional circuit. In the vast majority of cases, this is the configuration that fits into an existing electrical panel without upgrading the service entrance. Load calculations are the responsibility of a master electrician; our role is to provide the manufacturer's values before anyone makes any promises. Our Saint-Édouard and Napierville articles discuss in detail how to select a model based on the panel.

In Baie-D'Urfé, the outdoor unit's dimensions mattered just as much as its amperage. At 822 × 550 × 352 mm and 35.5 kg, compared with 1,020 × 826 × 427 mm and 79 kg for the 42,000 BTU/h model, it fits in a narrow side yard bordered by a mature hedge, can be handled by two people without machinery, and does not require dismantling existing landscaping. Its published sound level of 54 dB(A) is 8 to 9 dB(A) below that of the larger models; decibel readings and their attenuation with distance are discussed in our Huntingdon article. Wall-bracket installation, which is genuinely feasible at this weight, is described in the Ahuntsic-Cartierville article.

Choosing both components: the decision that matters more than model selection

On a four- or five-zone project, we cover the house and discuss capacities. On a two-zone project, the house is not covered: we choose two rooms out of five or six. This selection appears in almost no quote, yet it determines whether the client will be satisfied.

One unit that distributes, one unit that serves

The rule we apply can be summed up in one sentence: for heating, we place an indoor unit where the heat can spread; for cooling, we place an indoor unit where the person is. These two approaches almost never point to the same room.

• Heat rises and circulates by convection whenever a space is open. An indoor unit installed in the ground-floor living area therefore partially serves the staircase and upstairs, even though it was not installed there.
• Cool air falls and does not rise. A ground-floor unit will never cool a closed bedroom upstairs. The complete stratification mechanism, including the 2 to 4 °C difference between the occupied zone and the ceiling, is explained in our Saint-Amable article.

With only two indoor units, we have to choose between a distribution unit and a service unit. That is exactly what we did here.

The method applied during the technical visit

We rank the candidate rooms according to five criteria, in this order:

1. Hours of occupied waking time. A room where people spend six hours a day takes priority over a larger room occupied two hours a week. It is the most predictive criterion for satisfaction, and it is rarely the one we use.
2. Seasonal behaviour. A room that is problematic only in July is not addressed like a room that is uncomfortable from November to March. We therefore classify each candidate as a “summer problem,” “winter problem,” or “both.”
3. Position within the space. A room open to the staircase redistributes air; a room enclosed at the end of a hallway redistributes nothing.
4. How the doors are used. A door that stays closed at night completely changes the calculation. That question concerns the occupants, not the floor plan.
5. Accessibility for maintenance. A filter that can be rinsed while raising your arms gets rinsed; a filter four metres above a staircase does not. Our Saint-Lazare article explains why accessibility is part of system sizing.

Why the living-room unit works in winter and the bedroom unit works in summer

The 12,000 BTU/h indoor unit serves the open living area on the ground floor. It accumulates the most operating hours over the course of a year: it carries the heating load from October to April, and some of its output naturally moves upstairs.

The 9,000 BTU/h head serves the upstairs bedroom. It is primarily there for the cooling season, when the closed door separates the room from the rest of the house and the upstairs accumulates the day's heat. In winter, its role becomes secondary: the baseboard heaters are often sufficient, the door is more likely to remain open, and a bedroom should in any case be cooler than a living room.

The two heads therefore each serve one season. This is the most useful way to present a two-zone project to a client, and it avoids the classic disappointment of someone who expected cooling everywhere.

117% indoor capacity: a seasonal mismatch

Twenty-one thousand BTU/h of indoor-head capacity on a unit whose modulated maximum is 19,800 BTU/h in cooling and 18,100 BTU/h in heating is justified by this seasonal imbalance rather than by the usual hourly-statistics approach. With two zones, the diversity factor loses its basis—a 110% to 130% calculation relies on a law of large numbers that does not apply to two rooms, as we explain in our Saint-Denis and Ahuntsic-Cartierville articles. What remains valid here is that the two heads do not work hard at the same time of year.

What we do not promise for rooms without a head

This section appears in our signed end-of-project report because it prevents nearly all misunderstandings about a partial project:

• A closed door cancels everything. A secondary bedroom whose door remains closed receives neither cool nor warm air. No louver setting or fan speed can compensate.
• A hallway does not serve a bedroom. The limitations of a hallway head, including the clearance under doors and transfer grilles, are documented in our Saint-Cyprien-de-Napierville article.
• The basement is not served. A wall-mounted head on the main floor does not send air downward.
• The baseboard heaters remain in service everywhere, set below the temperature settings of the heads.
• There is no third port. The GWHD(18)ND6MO accepts two indoor units—two and only two; adding a zone later means installing a second complete system. The comparison with the GWHD(24)ND6MO, which accepts two to three units, is discussed in our Ahuntsic-Cartierville article. We ask the question when preparing the quote and write the answer into the estimate.

If you are interested in only one room

A word of honesty that sometimes costs a sale: the GWHD(18)ND6MO requires two indoor units. A home that only needs to cool and heat one room does not need a FreeMatch system, but rather a single-zone wall-mounted heat pump, which is less expensive and better suited. We say so before the order, not afterward.

About the photograph of this installation work

The image provided with this case shows a white wall-mounted head installed on the wall band above a closet with folding doors, in a child’s bedroom, with the display reading 61. This type of installation—the band above a closet, the closet used as a service route, the closet lintel not being a structural lintel, and the particular considerations of a wall-mounted heat pump in a child’s bedroom—is covered in detail in our article on an installation in Terrasse-Vaudreuil. We refer you there rather than repeat that content. One useful clarification: the 61 display is a value in degrees Fahrenheit, approximately 16°C, meaning a commissioning setting rather than a normal operating setpoint. Our Saint-Édouard article explains why a very low setpoint does not cool a room faster.

Baie-D'Urfé: What the Territory Requires

Baie-D'Urfé is a city in the Montreal metropolitan community, in the western part of the island, reconstituted on January 1, 2006, after the 2002 merger. It covers approximately 6 km² of land between Highway 40 and Lake Saint-Louis, has fewer than 4,000 residents, and its residential sector is characterized by large lots, no sidewalks, and mature tree cover. An industrial park occupies approximately one-third of the territory, north of Highway 20. The city has been officially bilingual since 2005, and its built heritage notably includes the Rangé-dit-Laviolette house, a stone farmhouse dating to around 1700, along the lakeshore.

Three consequences for a heat pump installation in Baie-D'Urfé:

1. Trees. Mature tree cover is a real asset for air conditioning, since a shaded outdoor unit works less hard. In return, it brings samaras, resin, and debris that lodge between the fins without ever triggering an error code: capacity drops, and no one is warned. Annual cleaning of the outdoor coil is a performance requirement, not an option sold three years later. The City also regulates tree removal by permit; if creating clearance requires cutting trees, the process must be completed with the municipality before the work begins.
2. Large lots. They expand the choice of installation location, which is a luxury. On the other hand, they require checking the snowblower’s route and the area where snow will be discharged, and sometimes extending the line—which, on a unit with a 10 m precharge, immediately costs extra refrigerant.
3. Municipal regulations. Setbacks from property lines, front-yard restrictions, and noise limits at the property line vary from one West Island municipality to another. We verify these points before choosing a location, as explained in our Huntingdon article; the municipal regulations section of our website lists this information for cities in Greater Montreal, and our office also answers these questions by phone.

Mistakes to avoid on a two-head project

• Removing the baseboard heaters after installation. With this model, there is no heating reserve above the rated capacity.
• Choosing the two largest rooms. The right question is the number of waking hours spent there and seasonal behavior, not square footage.
• Buying a larger unit “for extra capacity.” With two zones, it results in a higher modulation floor, a heavier, noisier, and more expensive unit, with no usable benefit.
• Failing to repeat the A2L verification after the final line routing.
• Signing without the AHRI code corresponding to the actual configuration. An AHRI rating qualifies an outdoor-and-indoor combination, not a unit alone; our Saint-Anicet article explains why a grant application hinges on this.
• Neglecting to register the warranty, which extends coverage from 10 to 12 years with proof of installation. We do this with the customer at the end of the project.

Commissioning, maintenance, and financial assistance

Commissioning includes deep evacuation with a rise test below 500 microns, weighing in any additional refrigerant, functional testing of one head at a time in both modes with physical verification of the room being served, and recording the serial numbers associated with each room. Routine maintenance consists of rinsing the filters every 4 to 8 weeks during the intensive season and annually cleaning the outdoor coil: with two zones, the maintenance workload is the lowest in the entire range.

As for financial assistance, a residential installation may qualify for LogisVert, and the application may be part of a Rénoclimat process; the Chauffez vert program does not apply to a home already heated with electricity. The criteria change, and we validate them when the application is opened rather than announcing them in an article.

For a wall-mounted heat pump installation in Baie-D'Urfé, the West Island, Montreal, Laval, Longueuil, the North Shore, or the South Shore, our team first determines which rooms need to be served, then chooses the model. For a two-zone project, that order makes the difference between a comfortable home and two units on the wall.