Installation of a GREE FREEMATCH R32 4-head wall-mounted heat pump (GWHD(36)ND6MO) in Saint-Denis-sur-Richelieu

Four rooms, four heads, one compressor: how to air-condition a ductless village house

The village core of Saint-Denis-sur-Richelieu consists of old homes: thick walls, original woodwork, high ceilings, and not a trace of a duct network. These homes endured 150 winters with stoves, then baseboard heaters. They never had a comfortable summer.

The house in this project belongs to this category. Four spaces to condition, no vertical utility shaft, no desire to drill through the original moldings, and an electrical panel that was already heavily loaded. The answer is the multi-zone system, more specifically the GREE FREEMATCH R32 in a 4-head configuration.

What the customer wanted, and what they feared

The initial request was simple: air conditioning in the bedrooms and living room, plus supplemental heating for the fall and spring. The concerns, however, were more revealing—and they are the same ones we hear throughout the Richelieu Valley:

• Visible pipes on an old façade.
• An electrical panel that needs to be replaced to power four units.
• A noisy outdoor unit three meters from the neighboring house.
• The classic question: four heads on a single compressor—is that really enough?

This final question deserves a numerical answer, because that is where performance and disappointment are determined.

The installed system

Outdoor unit: GREE FREEMATCH R32, model GWHD(36)ND6MO, reference number AHRI 214931589 (ductless configuration).

Indoor configuration: four wall-mounted heads, distributed as 9,000 + 9,000 + 12,000 + 12,000 BTU/h, for a total of 42,000 BTU/h of installed indoor capacity.

Diversity: 42,000 BTU/h of heads on a 36,000 compressor

This is not a calculation error, and it is the first thing we explain.

A multizone system does not add up the capacities of its heads. The compressor supplies a single refrigerant circuit and distributes its capacity among the units calling at a given moment. We deliberately install more indoor capacity than outdoor capacity, relying on the fact that the four rooms never reach their peak at the same time. This is what is called the diversity factor.

In cooling mode, diversity works in our favor

An east-facing bedroom heats in the morning, the west-facing living room heats in the late afternoon, and the north-facing office never really heats. The peaks follow one another instead of overlapping. An indoor capacity ratio of 117%, as here, is comfortable: each room receives its full capacity when it needs it, and the compressor drops to 8,870 BTU/h when only one head is running—which produces long cycles and genuinely dries the air, something four window air conditioners never do.

In heating mode, it works against us

At -25 °C, all rooms call for heat at the same time. There is no diversity at all. This is the scenario in which an improperly sized multizone system falls short, and it is precisely what most quotes leave unmentioned.

Our approach on this project:

1. Choose a compressor whose peak heating output exceeds the combined capacity of the heads. The GWHD(36) modulates up to 51,180 BTU/h in heating, well above the 42,000 BTU/h installed indoors. The constraint then becomes the individual capacity of each head, not that of the compressor.
2. Keep the existing electric heating in the most exposed rooms, with thermostats set a few degrees below the heads' setpoint. The multizone system handles most of the year; the baseboards only come on at the extremes.
3. Document the switchover point with the client, so they know at what outdoor temperature it is normal for supplemental heat to activate.

Why not the GWHD(30), better on paper

The next-smaller model also supports four heads, and its figures are better: COP of 4.19 versus 3.56, EER 2 of 12.5 versus 12.0, with the same SEER 2 of 21. On a comparison sheet, it wins.

It falls short on the only criterion that matters in February: its heating capacity peaks at 40,900 BTU/h, compared with 51,180 BTU/h for the GWHD(36). With 42,000 BTU/h of indoor units installed, the GWHD(30) would have been in a permanent deficit as soon as all four rooms called for heat at once.

We should also point out that the figures printed on the documentation cover — 21 SEER 2, 12.5 EER 2, 10 HSPF 2 — combine the best values from several models. The 12.5 EER 2 belongs to the GWHD(18) and GWHD(30), not to the model installed here. Verification is always done using the AHRI code for the exact combination, never the cover page.

A single electrical circuit for four rooms

That is the structural advantage of a multizone system, and it resolved the concern about the electrical panel in one sentence: the indoor units are powered by the outdoor unit. No indoor unit has its own circuit. There is only one connection to make at the panel, sized according to an MCA of 30 A and a maximum protection of 45 A.

Four single-zone systems would have required four circuits, four breakers, and four outdoor units. The FREEMATCH R32 requires only one, with one interconnection cable per indoor unit.

The multi-split limitation that almost nobody mentions

All the indoor units on the same system share a single refrigeration circuit and a single reversing valve. The direct consequence: they all operate in the same mode at the same time. It is impossible to cool the south-facing living room while heating the north-facing bedroom.

In July and January, this does not matter at all. In May and October, it can matter. Here is how we work around this limitation:

• Group rooms by orientation and use when choosing the indoor units, rather than following the layout of the house.
• Use fan-only mode in the room that is out of sync during the shoulder seasons.
• Keep a separate single-zone unit for a truly atypical room — a solarium, a south-facing office with large windows — rather than adding it to the multizone system.

We prefer to explain this before signing. It is a characteristic of the technology, not an installation defect, but a client who discovers it in October feels they have been poorly served.

Four refrigeration lines in a 19th-century house: the real challenge

The unit can be chosen in an hour. The routing of the lines, however, determines the visual result and the installation's service life.

Eight pipes leaving the outdoor unit

Each head requires its own set of lines: a 1/4 in liquid line and a 3/8 in gas line. Four heads therefore mean eight copper tubes leaving the compressor, each insulated, each with its interconnection cable and drain.

This is a volume that homeowners almost always underestimate. Our method:

• Group the runs as soon as they leave the unit, in a generously sized line set cover rather than three mismatched small conduits.
• Follow the building's architectural lines—under a drip edge, along a door or window casing, in an inside corner—rather than taking the shortest route.
• Choose the color of the line set cover based on the siding, not on what is available in the truck.

On an old village façade, this concealment work accounts for a significant portion of the job time and does not appear on any competing quote.

Calculating the additional charge

The GWHD(36) is precharged for 40 m of piping and accepts a total of 80 m distributed among the four heads. Beyond the precharged length, 20 g of R32 per meter must be added.

We measure each run, add them up, calculate the difference, and weigh the addition on an electronic scale before recording it on the unit's label. A four-head multi-zone system quickly accumulates length: three heads at 12 m and one at 18 m already total 54 m, or 14 m beyond the precharge and 280 g of refrigerant to add. An “estimated by ear” charge on a multi-zone system is the leading cause of service calls we take over from other installers.

The maximum 25 m elevation difference caused no problems here, but it is worth checking in three-story village homes with three habitable levels.

Drilling through old walls

The walls of these homes cannot be drilled like the wall of a 2004 timber-frame house. We locate the structure before drilling, drill at a slope toward the outside, sleeve every penetration, and seal it in a way that maintains the continuity of the air barrier. Canned urethane sealant is not a durable weatherproofing method for an exposed penetration: it yellows, cracks, and lets water and vermin in after a few years.

The condensate from four heads

Every wall-mounted head produces water in cooling mode. Four heads, four drains. Each drain must have a continuous slope along its entire route—that is the simplest and most frequently violated rule. Where gravity is insufficient, we install a condensate pump with a high-level safety switch rather than improvising a flat route that will back up into the wall in July.

Head placement

In the installation photo, the head is mounted high on a wall, above an original window with its wooden frame. This is not merely a default aesthetic choice:

• Clearance from the ceiling and sides determines air intake; a head wedged into a corner recirculates its own discharged air and reads an incorrect temperature.
• The airflow reach must cover the length of the room, not hit a wall two metres away.
• The chosen wall must allow the lines to exit on the correct side without passing through an adjacent room.
• The height must remain compatible with the homeowner cleaning the filters themselves.

The outdoor unit in a village centre

The GWHD(36) is rated at 63 dB(A), the highest value in the FREEMATCH R32 range. In the historic village centre of Saint-Denis-sur-Richelieu, where houses are close together and hard surfaces reflect sound, this figure is not insignificant.

Our precautions: keeping the units away from bedroom windows—both the neighbour's and the client's—not placing them in enclosed corners that amplify reflections, using anti-vibration mounts, and checking the municipal noise regulations in advance. We systematically verify this point before installation, because relocating a unit afterward costs more than placing it correctly the first time.

R32 and leak detection

R32 is an A2L refrigerant with low global warming potential, and the FREEMATCH R32 series includes a leak detector in the indoor units. With a multi-zone system, this precaution makes particular sense: the circuit is longer, has more connections, and passes through more occupied rooms than a single-zone system.

Mistakes to avoid with a multi-zone system

1. Put a head in every room by default. A 9,000 BTU/h head in a 100 sq. ft. bedroom is oversized: it short-cycles, dehumidifies poorly, and costs unnecessarily more.
2. Add up the heads to choose the compressor, without considering the heating peak.
3. Ignore the single-zone constraint and discover it during the shoulder season.
4. Estimating the refrigerant charge instead of measuring the line lengths and weighing the additional charge.
5. Adding multiple small line covers on a facade instead of using a planned, consolidated route.
6. Neglecting the slope of just one of the four drains.
7. Choosing the highest-rated model on paper without checking whether it can handle the actual heating load.

Maintaining four heads

A multi-zone system requires four times more filter cleaning than a single-zone system—that's arithmetic, and it's the task homeowners abandon first. We leave a simple instruction: rinse the filters every four to six weeks during the cooling season, on all four heads, not just the one in the living room. Annual HVAC maintenance covers coil cleaning, drain checks, pressure checks, and inspection of the connections throughout the system.

Financial assistance

Efficient multi-zone systems installed to replace or supplement electric heating are among the equipment covered by Quebec energy-efficiency assistance programs. Since eligibility criteria are based on certified performance ratings, verification is done using the AHRI code for the installed combination—here, 214931589—not the commercial name. Amounts and conditions change from year to year; we confirm eligibility when preparing the quote rather than after installation.

Our work in the Richelieu Valley

We install central and multi-zone systems on both sides of the river: reusing an existing duct network in Beloeil, creating a complete network from scratch in Mont-Saint-Hilaire, and installing a central system in a 42-inch crawl space in Saint-Mathias-sur-Richelieu. In older village centers such as Saint-Denis-sur-Richelieu, the multi-zone system almost always comes out on top because it conditions four rooms without requiring a single duct.

Our teams serve Saint-Denis-sur-Richelieu, Saint-Charles-sur-Richelieu, Saint-Marc-sur-Richelieu, Saint-Antoine-sur-Richelieu, Saint-Hyacinthe and the entire South Shore, as well as Montréal, Laval, Longueuil and the North Shore. For an older home without ductwork, the visit always begins the same way: surveying the rooms to be treated and mapping the actual line routes before proposing a model.