Installation of a GREE FreeMatch R32 dual-zone wall-mounted heat pump (GWHD(24)ND6MO) in Beaconsfield, in Montreal’s West Island

For a two-head project, the right unit is not always the smallest one

A two-zone project is almost always sold the same way: two rooms, two heads, the smallest outdoor unit in the lineup, and the lowest possible price. This is a defensible approach, and it sometimes produces the right result. In Beaconsfield, we recommended the opposite, and it is worth explaining why in detail, because the difference between the two options is not apparent on any quote.

The GREE FreeMatch R32 lineup includes two outdoor units capable of serving two wall-mounted heat pumps: the GWHD(18)ND6MO, which accepts exactly two heads, and the GWHD(24)ND6MO, which accepts two to three. On paper, the former was more than sufficient for this house. In practice, three lines in the manufacturer's table tipped the decision toward the latter, and none of the three concerns capacity.

At AirGreen, we carry out HVAC installations in Montreal, Laval, Longueuil, on the North Shore, and on the South Shore. This West Island project provided an opportunity to document a selection decision we make regularly but had never put in writing before.

The Beaconsfield project at a glance

Beaconsfield covers approximately 10.64 km² along the shores of Lake Saint-Louis, in the western part of the Island of Montreal. The city has just over 19,000 residents; its Beaurepaire sector is the oldest—the first land grants date back to 1698, and the municipality was incorporated in 1910—and most of its residential housing stock was built between the late 1950s and the 1960s: Kensington Gardens, Forest Garden, Drummond Park, Beacon Hill. The terrain is flat, the streets are lined with mature trees, and single-family homes predominate. This housing stock has one very clear characteristic in common: it was designed for heating, never for air conditioning.

The home in question is a single-family residence of this type, with a renovated rear kitchen. Electric baseboard heating, no ductwork, no central system, and a little-used finished basement. The owners were not looking to convert the entire house: they wanted to treat two specific areas, the large rear kitchen-dining room and the primary bedroom upstairs, while keeping open the possibility of adding the basement later.

Selected configuration:

• Outdoor unit: GREE FreeMatch R32 GWHD(24)ND6MO
• Head 1: 12,000 BTU/h wall-mounted unit, rear kitchen-dining room
• Head 2: 9,000 BTU/h wall-mounted unit, primary bedroom upstairs
• Installed indoor capacity: 21,000 BTU/h, or 88% of the outdoor unit’s nominal capacity
• Third port: free, reserved for the basement
• AHRI codes: 214931587 (ductless), 214931593 (ducted), 214931597 (mixed)
• Total line length: approximately 9 m and 14 m, for 23 m total

Let’s note the ratio right away: 88 %, an installed indoor capacity lower than the unit’s nominal capacity. This is unusual in this series, where the ratios most often range from 100 to 130%. It is also a direct consequence of the model choice, not a sizing defect.

The three lines in the table that drove the decision

The table below compares the only two FreeMatch outdoor units capable of serving two heads.

The GWHD(18)ND6MO is not a bad unit. We recently installed it in a semi-detached home in Ahuntsic-Cartierville and in a house in Baie-D'Urfé, where it was the right choice each time, and our articles on those two projects explain why. But three lines in this table worked against it in Beaconsfield.

First line: two, never three

The GWHD(18)ND6MO accepts two indoor units. Not “two to three”: two. Once the second head is connected, the system is complete for life. Adding the basement four years later then means a complete second system—second outdoor unit, second electrical circuit, second spot on the property, and second HVAC maintenance contract.

We had flagged the same constraint at the other end of the lineup in our Sainte-Martine article: on a five-head system, using the fifth port permanently eliminates the free-port argument, because no FreeMatch model accepts six.

In Beaconsfield, the finished basement was explicitly part of the homeowners' plans, with no set deadline. The third port on the GWHD(24)ND6MO turns this future project into a one-day visit rather than a second full installation. This is the first time in this series that expansion capacity is actually being preserved rather than announced and then consumed.

Second point: heating reserve

The manufacturer's table indicates that the GWHD(18)ND6MO has a modulated heating range of 7,300 to 18,100 BTU/h for a nominal rating of 18,000. In other words, virtually no reserve above the nominal rating—an isolated case in the lineup, which we analyzed in detail, with a comparison table, in our Baie-D'Urfé article. We also point out there, in full transparency, that this line could be a typo in the sales documentation: we do not have an installation manual to corroborate it, and our position is to treat it as accurate rather than sell reserve capacity that appears nowhere.

The GWHD(24)ND6MO, meanwhile, modulates up to 31,400 BTU/h in heating for a nominal rating of 24,000—about 30% of available reserve, comparable to the higher-end models in the lineup.

In plain terms, in Beaconsfield: moving from 18,000 to 24,000 BTU/h does not provide an additional 6,000 BTU/h of peak heating capacity; it provides more than 13,000. In a 1960s West Island home heated with baseboards, where the balance point occurs in January rather than November, that is the difference that matters—and it alone justifies a substantial part of the price difference.

Two honest clarifications accompany this section in our quote:

• No electric baseboard is being removed, regardless of the model. The baseboards are not a leftover; they are the peak backup, and we set them 2 to 3°C below the head-unit setpoints so that they only come into play when the heat pump is no longer sufficient.
• An operating range is not a capacity. The specification sheet states that heating operation is possible down to -30 °C without publishing any low-temperature capacity data. We wrote this to Franklin and repeat it here: the question to ask any contractor is “what is the capacity at -20 °C, and where is my balance point?”

Third line: the 30 metres of precharge

The GWHD(18)ND6MO leaves the factory with 900 g of R32, an amount calculated for 10 m of total piping—not ten metres per head, but ten metres for the entire system. Beyond that, the installer adds refrigerant at a rate of 20 g per metre. We published the complete arithmetic for this calculation, and its consequences for the minimum room-area requirement related to A2L refrigerant, in our Ahuntsic-Cartierville article, where exceeding the limit was unavoidable.

The GWHD(24)ND6MO is precharged for 30 m. In Beaconsfield, the two runs measured on site total 23 m. In other words: not a single gram of R32 was added to the system.

This detail has three concrete consequences, and the middle one is the one that interests us most.

1. Less handling, less risk of variation. An intact factory charge is an exact charge.
2. The minimum room-area requirement remains the one shown on the nameplate. R32 is a mildly flammable refrigerant, and indoor units therefore bear a nameplate specifying a minimum installation height and a minimum room area—we published these values as read from a nameplate in our Dundee article, noting that they depend on the model and the charge. That last word is what matters: when refrigerant is added, the requirement increases, and the assessment of the smallest room served must be redone after the runs have been measured, not at the time of submission. Here, since the charge did not change, the assessment made from the plans remains valid as is.
3. The margin is real. With 23 m of installed piping out of a maximum of 60 m and approximately 4 m of elevation out of a maximum of 15 m, a third run to the basement remains entirely feasible without redesigning the installation.

On the smaller model, those same 23 m would have required 13 m of additional charge, or 260 g added to a factory charge of 900 g—nearly a 29% increase, along with a mandatory revision of the A2L assessment. The calculation would still have been done correctly, but the project's flexibility would have disappeared.

What the superior model really costs

We never present an upgrade without stating its technical cost. The GWHD(24)ND6MO costs more to purchase, and it also costs four other things.

• 4 dB(A) louder: 58 dB(A) versus 54. We explained to Huntingdon how to interpret a published sound level without a measurement distance; suffice it to say that a 4 dB difference is audible, though not in the same league as the 9 dB separating the small model from the larger ones. On a Beaconsfield property, where the houses are not tightly packed, the difference was deemed acceptable after locating the neighbours' bedroom windows.
• 15.5 kg heavier and a larger footprint: 51 kg and 964 × 660 × 402 mm versus 35.5 kg and 822 × 550 × 352 mm. The choice between a base on a stone bed, piles, and a wall bracket was addressed in Rigaud, and the ground installation selected here posed no difficulty.
• 5 A more in maximum protection: 25 A versus 20 A. Since the indoor units are powered by the outdoor unit, a single circuit serves the entire system. Load calculations under the Code are the responsibility of a master electrician—we detailed this reasoning in Saint-Édouard and Napierville—and our contribution remains the manufacturer's data. On this panel, the difference fit.
• Half a point of EER2: 12 versus 12.5. Worth noting, because the sales sheet invites confusion: EER2 and EER are not the same measurement and cannot be compared with each other. The 24,000 BTU/h model has a lower EER2 but a higher EER (3.80 versus 3.52 W/W). Compare one EER2 with another EER2, period.

One final reading note that applies to the entire range: the cover page of the FreeMatch documentation states “maximum piping length: 100 m.” That figure applies only to the GWHD(42)ND6MO. On the unit installed in Beaconsfield, the limit is 60 m, and 40 m for the smallest model. It is the same process as with the efficiency ratings, where the EER2 of 12.5 displayed on the cover applies to only two of the five models. The cover values describe the top of a range, never the unit being installed.

Technical data sheet for the installed outdoor unit

Leak detector A2L Integrated, G10 inverter technology, intelligent defrosting, automatic voltage adaptation, and self-diagnostics are common to the entire range.

Choose the two rooms, then learn to live with two zones

With a five-head system, the question of zoning practically resolves itself: each enclosed room gets its own head. With a two-head system, zoning is the project. Two rooms are treated, all the others are not, and the comfort gap between the two categories becomes apparent during the first heat wave.

The rear kitchen as the primary zone

The construction-site photograph shows the 12,000 BTU/h head installed high on the kitchen's rear wall, just above the casing of the garden door topped by its glazed transom. Below and to the left, a counter with an open shelf, tea boxes, a grinder, and a coffee maker; to the right, the ceiling drop; in the ceiling, a recessed light a few dozen centimeters from the unit.

The choice of the kitchen rather than the living room deserves an explanation because it goes against the instinct to treat the largest room.

In a house, the kitchen is the room with the highest internal gains: oven, cooktop, dishwasher, refrigerator, small appliances, and occupants present during the hottest hours of the day. Its cooling load is not proportional to its floor area. We made the same point in a commercial setting in Pointe-des-Cascades, where the service counter had been given the same capacity as the dining room because the refrigerated equipment was located there. The residential version is more modest but follows the same logic: here, the kitchen-dining room was assigned 12,000 BTU/h, whereas a square-foot calculation would have yielded 9,000.

An exposure factor also comes into play: this room opens onto the courtyard through a glass door and a window, giving it solar gains that the rest of the ground floor does not have.

As for the overall 88% ratio, it follows from a line of reasoning we stand by: the unit's capacity was not chosen to be “filled” by the heads. A system whose installed indoor capacity remains below its nominal capacity never deprives a head of power when both call for it at the same time—and with only two zones, simultaneous demand is not an unlikely scenario; it is the usual case on a summer evening. We had adopted the same deliberate capacity-gap logic in Beauharnois, with four heads.

A head fitted against a ceiling soffit: the clearances are not symmetrical

In the photo, the unit's right end practically touches the vertical face of the ceiling soffit. This is the kind of detail that catches a trained eye, and it deserves a precise explanation, because the actual rule is more nuanced than “there must be space around it.”

Installation manuals for indoor units specify clearances on each side, and these clearances are not the same on the left and right. The side where the refrigerant lines, condensate drain, and interconnection cable exit requires more space: the copper tubing's bending radius must be respected there without crushing the insulation, and the drain slope must be maintained from the unit's outlet. The other side is used only for airflow and removal of the indoor filters.

The practical consequence, which we apply systematically: the side we mount against is the side without the connections. The drain outlet direction must therefore be decided before securing the mounting plate, never afterward—we had already pointed this out in Les Coteaux, where an interior window had dictated it. In Beaconsfield, with the soffit on the right, all the connections were oriented to the left, where the wall surface was unobstructed.

Two checks complete the process, and they are done with a tape measure before drilling, not by eye once the unit is hung:

• The clearance above the unit, which determines air recirculation. A unit installed too tightly under the ceiling draws its own discharged air back in and relies on a false return-air temperature reading. We developed this mechanism in Verchères and Saint-Polycarpe.
• Access to the filters with the unit in place: the panel must be able to lift and the filters must be removable without hitting the soffit. A filter you cannot remove is a filter that does not get cleaned.

What a 1960s kitchen ceiling soffit contains

The soffit was not merely a constraint: it also made it possible to avoid opening up a freshly finished kitchen wall. The ground-floor header layout runs through it.

In a West Island house from this period, a kitchen soffit very often conceals something else: a plumbing stack, an old range hood exhaust duct, or wiring redone over several periods. A stud finder detects a mass, not its nature. We therefore open an inspection window before any drilling—the method is detailed in our Saint-Étienne-de-Beauharnois article—and take the opportunity to perform two checks that are impossible once everything is closed up: insulation continuity along both refrigeration lines, and the drain's continuous slope along its entire route.

It is also this drop that makes a future basement addition feasible: the route for the third head will use the same passage, already located and documented in the file.

The ceiling recessed unit: why this one does not cause a problem

A ceiling light fixture in the immediate vicinity of a wall-mounted head is often a source of concern, and rightly so: in Sainte-Martine, we documented how a pendant light, beam, or ceiling fan breaks the airflow jet running along the ceiling and makes it drop too soon.

A recessed unit is the opposite case, and it is good news worth stating: it is flush with the surface, has no projection, and therefore does not disrupt the airflow. The only precaution concerns its installation—locate its housing and wiring before drilling, because they occupy the ceiling void exactly where we want to route the line.

Above a garden door

Positioning a head above a door is common practice and often the only option: it is the only clear strip of wall when windows, cabinets, and the backsplash occupy all the remaining space. We addressed the geometry of this situation in Varennes, Verchères, and Havelock—with the structural lintel never drilled, the door swing verified, and clearances respected.

What needs to be added in the kitchen context can be summed up in one sentence: a garden door is opened frequently in summer, often remaining ajar, and each opening sends a mass of outdoor air along the wall to the return grille located on top of the unit. The return sensor then reacts to a thirty-second event. In residential use, the phenomenon remains marginal compared with what we observed at a commercial entrance in Pointe-Fortune, but it justifies two simple commissioning corrections: increase the minimum fan speed by one setting in this zone, and shift the head laterally from the door's axis when the wall allows it.

The kitchen is the most demanding room for an indoor filter

An indoor unit installed in a kitchen receives cooking aerosols. They pass through the indoor filter, deposit as a film on the evaporator fins, trap dust, and feed a biofilm in the condensate pan. We developed this mechanism in Saint-Stanislas-de-Kostka; fouling caused by operating products falls under HVAC maintenance, never the warranty.

On this project, one specific factor calls for extra vigilance, and it is visible in the photo: the indoor unit is above a countertop with a coffee maker, grinder, and kettle. Steam from an espresso machine and a kettle rises straight toward the return grille several times a day, all year round—adding moisture and fine particles that do not appear in any calculation and that never stop outside the intensive cooking season.

Our schedule for this home:

• Kitchen zone: rinse the filter every 4 weeks during the intensive season.
• Bedroom zone: rinse every 8 to 12 weeks.
• A kitchen range hood vented outdoors and actually used. A recirculating hood sends the aerosol back into the room, and therefore into the unit.
• Deep cleaning of the heat exchanger and blower wheel by a technician on a shorter cycle than the residential average.
• And one firm prohibition: never spray household cleaner into the fins. It attacks the aluminum, leaves a residue that the unit then redistributes into the room, and the fins bend at the slightest contact.

One mode for two zones: the constraint becomes a fifty-fifty proposition

Like any multizone system with a single refrigerant circuit, the FreeMatch cannot heat and cool at the same time. All indoor units share one mode. We explained the mechanism in detail in our first article in the series, in Saint-Denis-sur-Richelieu.

What changes with two zones is the scale of the consequence. With five zones, a mode conflict affects one room out of five. With two zones, it affects half of your installation. That is the distinction we want to explain before signing rather than at commissioning.

In Baie-D'Urfé, we published the complete method for selecting the two rooms—occupied waking hours, seasonal behavior, position within the volume, actual door usage, and maintenance accessibility. What we add here is a compatibility rule that we now apply to every two-zone project: the two zones must have seasonal needs that move in the same direction. A rear kitchen and an upstairs bedroom are very similar in this respect—both overheat in summer and both call for heating in winter. Two rooms with opposite exposures, such as a south-facing office with a workstation and a north-facing bedroom, would have created a constant trade-off from October through November. In this situation, two independent wall-mounted units are a better choice than a two-zone system, even though they cost more to install and take up two outdoor locations. We compiled the complete list of situations in which two separate systems outperform a multi-zone system in our Franklin article.

The same rule applies to the future basement: a finished basement calls for heating in the same direction as the rest of the house, making it a compatible third zone. A workshop with full southern exposure would not have been.

Short cycling, for once, is not the main constraint

In almost every article in this series, we have had to point out the same drawback: the modulation floor is a system property, not a property of the head. On the GWHD(42)ND6MO, this floor is 8,870 BTU/h, which exceeds the capacity of a single 6,000 BTU/h head—a small room calling on its own will therefore operate in short cycles.

On the GWHD(24)ND6MO, the minimum operating level is 7,500 BTU/h, below the capacity of each of the two installed heads. The 9,000 BTU/h bedroom that calls on its own at three in the morning therefore remains above the minimum level, and the compressor can follow it through continuous modulation instead of starting and stopping. The full mechanism behind short cycling and dehumidification is explained in our articles on Saint-Chrysostome and Saint-Édouard.

One point to watch going forward, however: if the basement gets a small 6,000 BTU/h head and calls for heat on its own during the shoulder season, it will fall below the minimum operating level. The solution, already proven on our Saint-Urbain-Premier and Très-Saint-Rédempteur projects, is to run two zones together at a moderate setpoint rather than a single zone at full output. This is an operating instruction, not a technical correction, and it will be written on the sheet given to the homeowners when the third head is installed.

Mistakes to avoid on a two-head project

1. Choose the outdoor unit based solely on capacity. With two zones, capacity is rarely the limiting factor; the number of ports, the precharge, and the heating reserve are.
2. Overlook the question of the third port. It must be addressed before signing, not when the basement is finished.
3. Choose the model before finalizing the outdoor unit's location. For a unit precharged for 10 m, the routing is not an installation detail but a design parameter.
4. Estimate the additional charge instead of weighing it, when there is one.
5. Check the minimum room area at the quotation stage. It is verified once the final charge is known, against the nameplate of the delivered unit.
6. Remove the electric baseboards. On smaller models, the heating reserve above the rated capacity is small or even nonexistent.
7. Read the figures on the cover page as though they belonged to your unit. 100 m of lines and an EER2 of 12.5 do not belong to the same model.
8. Choose two zones with opposite exposures on a system that has only one mode.
9. Place the connection side against an obstacle because it is aesthetically less conspicuous.
10. Treat the kitchen as an ordinary room in the maintenance schedule.
11. Have it installed by an unlicensed RBQ contractor. This complicates both the manufacturer's warranty and any subsequent insurance claim.

HVAC maintenance: what changes when there are only two heads

Fewer heads means fewer filters, fewer pans, and fewer drains — but it does not mean less maintenance per unit. The program selected in Beaconsfield:

• Rinse the indoor filters according to the staggered schedule described above.
• Annual cleaning of the outdoor heat exchanger. Beaconsfield is a city with mature trees, and a coil that becomes dirty does not trigger an error code: capacity is lost without warning. Problems specific to units installed under trees are detailed in our Rigaud article.
• Annual inspection of both pans and both drains, including the outdoor discharge point.
• Run both heads in both modes for about thirty minutes each month, including during the off-season. An idle zone leaves an inactive expansion valve and a pan that dries out and then fills with dust.
• Recording the serial numbers of each indoor unit in the file along with the corresponding room, measured lengths, intact factory charge, and commissioning readings — without forgetting the marked routing for the third head.

Grants and documentation

An efficient wall-mounted heat pump installed in a residence may qualify for residential assistance programs, particularly through Hydro-Québec and Rénoclimat. The criteria, efficiency thresholds, and terms change regularly: we verify eligibility when the file is opened, without announcing an amount in advance.

An administrative point that few contractors explain: SEER2, HSPF2, and EER2 ratings certify a combination of an outdoor unit and indoor units in a given configuration, which explains the three sets of AHRI codes published for each model—ductless, ducted, and mixed. The code declared in the file must correspond to what was actually installed, and adding a third head later changes the combination. We developed this point in Saint-Anicet. Finally, the Chauffez vert program does not apply here: it targets the replacement of fossil-fuel heating, and this home was already heated with electricity.

Why entrust your installation to AirGreen

This Beaconsfield project can be summed up in one idea that is simple to state and difficult to sell: with a two-head system, the right equipment is chosen based on lines in the table that no one reads. The number of ports, the precharged line length, and the heating reserve determined this project—not the rated capacity and not the purchase price.

What we systematically put in writing before the work begins: the exact outdoor unit model and the reason for choosing it, the capacity of each head for each room, the planned line set lengths and estimated additional charge, the AHRI code corresponding to the actual configuration, the estimated balance point, the exact scope of finishing work, the retained expansion capacity—and what the system will not do.

We serve Beaconsfield, the entire West Island, Montreal, Laval, Longueuil, the North Shore, and the South Shore for HVAC installation, commissioning, and HVAC maintenance of wall-mounted and multi-zone systems.

Have your project assessed

If you are considering a two-zone heat pump in a West Island home, the first step is not choosing a model: it is measuring the layouts, determining which rooms could be added over the next five years, and checking what your electrical panel can actually support. Contact AirGreen for an on-site technical assessment, a detailed room-by-room quote, and an installation schedule.