Installation of a 4-head GREE FREEMATCH R32 heat pump (GWHD(42)ND6MO) in a commercial office in Sainte-Julie, Montérégie

Four zones, one compressor, and offices that could not close

The assignment came to us at the beginning of August: a commercial premises in Sainte-Julie, occupied by about fifteen people from Monday to Friday, with a south-facing open area, a glass-walled meeting room, two enclosed offices at the back, and a portable air conditioner venting its hot air through a partially open window. Heating was provided by electric baseboards. The employer gave us one condition: operations could not stop. No closure, no break week, and no temporary relocation of workstations.

This type of constraint determines a system's design far more often than the catalog does. We selected a GREE FREEMATCH R32 multi-zone wall-mounted heat pump, with a GWHD(42)ND6MO outdoor compressor and four wall-mounted heads distributed according to the actual occupancy of the spaces. Here is how we arrived at this solution, what the project required, and what we would have refused to do if the client had asked.

The building before our visit

The premises occupy the ground floor of a two-story commercial building, a few minutes from access to Highway 20 and Highway 30. Suspended ceiling with acoustic tiles, recessed LED lighting, drywall partitions on steel studs, and large street-facing windows with solar shades.

The thermal assessment was typical of an office and, in contrast to a house, had internal gains dominating. About fifteen computer workstations, two multifunction printers, a small server room, lighting, and especially the occupants themselves produced an air-conditioning load that persisted even in cool weather. The concrete result observed on-site: in April, the open area was already calling for cooling while the offices at the back, on the north side, were still calling for heat. This simultaneity is the project's central technical issue, and we return to it below because it imposes a real limitation on any multi-split system.

Why the GWHD(42)ND6MO instead of the 30,000 or 36,000 BTU

The FREEMATCH R32 series includes five outdoor compressors: GWHD(18), (24), (30), (36), and (42)ND6MO. Three of them can power four heads. The choice was not based on nominal capacity alone.

Three factors were decisive.

Piping length. The only acceptable outdoor location—we will return to this—was at the rear of the building, far from the heads. Adding the four runs together, we exceeded what the 36,000 BTU/h chassis allows. The GWHD(42) permits 100 m total and 50 m factory precharged, which made the difference between a compliant system and one outside the manufacturer’s specifications.

Room for growth. The GWHD(42) is the only model in the series that accepts up to five indoor units. The tenant is considering creating a fifth enclosed space within the next three years. A compressor limited to four heads would have meant a second complete system—therefore a second compressor, a second electrical circuit, and a second outdoor support bracket—for a single room.

Heating performance. With a COP of 3.9, the GWHD(42) outperforms the 36,000 BTU/h model (3.56) and approaches the 30,000 BTU/h model (4.19), while offering a significantly higher peak heating output. For a building aiming to reduce electric baseboard use in January, it is the most defensible compromise.

Worth noting, because the information is often misreported: the brochure cover states “up to 21 SEER2 / 12.5 EER2 / 10 HSPF2.” The 12.5 EER2 applies only to the 18,000 and 30,000 BTU/h models. Our unit is rated at 12 EER2, and we prefer to state that clearly rather than repeat the brochure’s figure.

The distribution of the four heads

The four indoor units are wall-mounted heads, which corresponds to AHRI 214931590 (ductless configuration)—a detail that matters for any financial assistance application or compliance file.

• Open-plan area, south side: 18,000 BTU/h, installed high on the partition wall, set back beneath the suspended ceiling grille.
• Meeting room: 12,000 BTU/h, the room whose load varies most dramatically—empty at 9 a.m., twelve people at 10 a.m.
• Enclosed north office: 9,000 BTU/h.
• Multipurpose room / kitchenette: 9,000 BTU/h.

Total indoor capacity: 48,000 BTU/h on a 42,000 BTU/h compressor, or a 114% diversity factor.

What indoor oversizing means, and where it becomes a trap

A multi-split is designed on the assumption that not all zones will call for their full capacity at the same time. In cooling mode, the assumption holds: the empty meeting room consumes nothing while the open area is operating, and the compressor modulates from 8,870 to 44,300 BTU/h.

In Quebec heating, the assumption is reversed. On a −22 °C morning, all zones call for heat at the same time, and the available capacity is shared among the indoor units. That is why we refuse to size a multizone system as though it involved adding four independent units, and why we kept the electric baseboard heaters as backup instead of removing them. They are almost never used; they serve the few days when they are needed.

The limitation few contractors explain: only one mode at a time

The four indoor units share a single refrigeration circuit and a single reversing valve. The system therefore operates in cooling or heating mode, never both simultaneously. If the open area needs cooling in April, the north office cannot receive heat at the same time.

We presented this constraint to the client before signing, with two options: accept the limitation and keep the baseboard heaters for the north offices in the shoulder seasons, or switch to a heat-recovery system at a completely different price point. The client chose the first option. It is a ten-minute conversation that prevents an angry service call six months later, and it is precisely the kind of verification to require from any commercial HVAC installation contractor in Montréal, Laval, Longueuil, on the North Shore or the South Shore.

The project: drilling, running wiring, and commissioning without interrupting a workday

The suspended ceiling, a conditional ally

The plenum space above the acoustic tiles allowed us to route the four refrigerant lines and drains without a single exposed raceway in the work areas. We still had to follow a few rules that haste often causes people to forget:

• Support the piping independently of the suspended ceiling grid. The T-grid supports tiles, not insulated copper lines or drains filled with water.
• Maintain a continuous slope on the drains along the entire length of the plenum, with no low points where water can collect and bacteria can grow.
• Never crush the copper insulation when routing it through a steel stud: bare copper against metal in a warm plenum creates condensation that eventually stains a ceiling tile—and the client will rightly blame the stain on the air conditioner.
• Seal the fire-rated penetrations in accordance with the required separation between the spaces.

Gravity drainage, and why we refused the pump

Three heads drained naturally by gravity toward the rear wall. The fourth, in the multipurpose room, would have required a condensate pump. Instead, we raised the head by 11 cm and modified the drain route through the plenum to restore the slope.

The reason is simple: a condensate pump makes noise, intermittently and at irregular intervals. In a bedroom, you get used to it. In a room where people make sales calls, it becomes a complaint that comes back every week. Our internal rule is clear: when a pump is unavoidable, the client is informed before installation, never afterward. Here, it was avoidable.

The electrical side: a single circuit for four zones

On the FREEMATCH series, the indoor units are powered by the outdoor unit. So there are not four circuits to run to four rooms, but a single circuit to the compressor, plus the communication cables.

For the GWHD(42)ND6MO: 208/230 V, 30 A MCA, 45 A maximum overcurrent protection (MOCP). In an already crowded commercial panel, this circuit savings was not cosmetic: it avoided adding a subpanel. The load calculation was still redone before ordering the equipment, with a disconnect located near the outdoor unit and clearances maintained around the existing electrical equipment.

The outdoor unit: 79 kg, 63 dB(A), and a neighbor

The compressor measures 1,020 × 826 × 427 mm and weighs 79 kg, with a sound pressure level of 63 dB(A) at high speed and an airflow rate of 3,413 cu ft/min. We installed it on a ground-level base at the rear of the building, on anti-vibration pads, while respecting:

• the service clearances required by the manufacturer in front of the coil and on the electrical-panel side;
• the distance from the property line and openings of the neighboring business—several municipalities in Montérégie regulate mechanical-equipment noise, and Sainte-Julie is no exception;
• sufficient ground clearance so that defrost water does not form a column of ice beneath the unit in February.

Smart defrosting and automatic voltage adaptation are part of the platform; the heating range is specified as −30 °C to 24 °C, and the unit carries ENERGY STAR certification, including cold-climate recognition.

R32, A2L sensor, and room volume

The system contains 2,700 g (95.3 oz) of R32 refrigerant, precharged for 50 m of piping, with a 20 g/m (0.2 oz/ft) additional charge beyond that. R32 is an A2L, mildly flammable refrigerant, and this requires a check that too many installers still overlook: the allowable charge depends on the floor area of the smallest room served and the mounting height of the head.

Specifically, we approved the north enclosed office—the smallest room in the lot—before confirming the configuration, and the heads were mounted high on the partitions, which improves dispersion in the event of a leak because R32 is heavier than air. The FREEMATCH series includes an A2L leak detection sensor as standard; this sensor is a mitigation measure, not an exemption from calculation.

Commissioning and the plastic film

A photo taken at the end of the project still shows the protective film on the wall-mounted head, with the yellow retaining tape on the louver. This is not an oversight: we leave the film in place until the very end, precisely because the work is taking place in an active office—with drywall dust from drilling, ladder handling above workstations, and boxes being moved back and forth.

Commissioning itself is non-negotiable:

1. Nitrogen pressure test of the entire system, maintained and documented.
2. Evacuation to a stable vacuum level, with a standing vacuum test—the only test that distinguishes a dry installation from one that will lose its compressor within three years.
3. Weighed refrigerant charge, calculated based on the actual measured line length, never estimated.
4. Checking every head: supply-air temperature, drain flow using poured water, communication addressing, and remote-control testing.
5. Training occupants on the modes, temperature setpoints, and scheduling of unoccupied periods.

These five steps took half a day. That is half the work that does not show up in the photos, and it is what determines whether the equipment will still be operating fifteen years from now.

The mistakes we see most often with commercial multi-zone systems

• Adding up the capacities of the heads as if they were independent units, without checking how the system performs in heating mode at full demand.
• Installing a head above a door or facing a glass partition, where the airflow is immediately redirected toward the return-air sensor and causes short cycling.
• Forgetting the server room in the calculations, then discovering that it requires cooling in January while the system is in heating mode.
• Ignoring the total line length and silently exceeding the manufacturer’s limit, voiding the warranty without anyone realizing it before the first breakdown.
• Having the system installed by a contractor without the appropriate RBQ licence, which can make the building’s insurance coverage questionable in the event of a claim.

Financial assistance and warranty

One point that causes a great deal of confusion: the programs homeowners know—LogisVert, Rénoclimat, Chauffez vert—are intended for residential properties. For a commercial building, eligibility goes through other channels, including energy-efficiency programs for Hydro-Québec’s business customers and, when replacing a fossil-fuel system, the ÉcoPerformance program.

Two rules almost always apply: eligibility must be confirmed before purchase (retroactive claims are generally denied), and the unit must be AHRI-certified and, depending on the program, ENERGY STAR-certified. Our office helps clients with this verification rather than promising an amount in a quote.

Regarding coverage, the FREEMATCH R32 series comes with a 10-year limited warranty on the compressor and parts, extended to 12 years when the unit is registered with Wolseley with proof of installation. We register it in the client's file; that is two additional years of coverage that many owners lose simply because no one completed the form.

Maintaining a multi-zone system in a workplace

An office clogs its filters faster than a residence: paper, carpet dust, and constant traffic. Our schedule for this client:

• Filters on all four heads: cleaning every 4 to 6 weeks with continuous use.
• Indoor coils and condensate pans: annual maintenance, before the cooling season.
• Outdoor coil: annual cleaning, plus removal of snow accumulated during the winter.
• Checking pressures and defrost operation: at every maintenance visit.

The built-in self-diagnostic feature makes troubleshooting easier, but it does not replace a technician taking readings. When just one head in a multi-zone system underperforms, the issue often goes unnoticed for two seasons because occupants eventually assume that “this room is just like that.”

Install a multi-zone heat pump in Montérégie

This Sainte-Julie project joins the installations we carry out in stores, offices, clinics, and multi-unit buildings in Montreal, Laval, Longueuil, the North Shore, and the South Shore. Every commercial HVAC installation starts with the same process: measuring actual loads, understanding the occupancy schedule, checking the electrical panel, verifying piping lengths, and explaining the system's limitations before selling it.

At AirGreen, we consistently prioritize the solution that lasts ten years over the one that can be installed in a day. For an assessment of your commercial space or building, our teams travel throughout Greater Montreal and Montérégie.