Installation of a 4-zone GREE FREEMATCH R32 heat pump (GWHD(36)ND6MO) in Saint-Marc-sur-Richelieu, MRC de La Vallée-du-Richelieu

Four rooms, four wall-mounted units, one refrigerant circuit—and a heritage home that leaves no room for shortcuts

The photo from this Saint-Marc-sur-Richelieu project shows almost nothing. A white wall-mounted unit installed perfectly straight beneath a ceiling molding, a plaster wall without a single mark, no visible line-set cover, and no hastily patched hole. That is exactly the intended result.

What the photo does not show is the rest of the system: three other wall-mounted units in three other rooms, a single outdoor unit, a single shared refrigerant circuit, a single electrical circuit, and a series of calculations completed before the first hole was drilled. A four-zone GREE FREEMATCH R32 multi-zone system is not four installations placed side by side. It is a single installation with four endpoints, and that difference changes everything—including what the customer needs to know before signing.

Saint-Marc-sur-Richelieu: the village core has its own rules

Saint-Marc-sur-Richelieu is a municipality in the Roussillon Regional County Municipality, in Montérégie, on the banks of the Richelieu River. Its village core contains many historic residences, several of which are listed in the Répertoire du patrimoine culturel du Québec, particularly along Richelieu Street. In practical terms, this means two things for a heat pump project.

First, the interior. Original plaster, ceiling moldings, wood floors, irregular wall thicknesses: every hole is permanent, and every visible line-set cover is a permanent aesthetic compromise. Then, the exterior. In a heritage district, the location of equipment visible from the street may be subject to a municipal bylaw, particularly a site planning and architectural integration bylaw. We therefore check the applicable requirements before proposing a location, rather than installing first and dealing with a complaint afterward. Our office team also assists clients on the South Shore with these regulatory matters by phone.

Installed system: FREEMATCH R32, model GWHD(36)ND6MO

The outdoor unit selected for this home is the GWHD(36)ND6MO, which accepts 2 to 4 indoor units—the exact limit for this four-unit project. Certified combination under AHRI code 214931589 in a fully ductless configuration (four wall-mounted units).

A single electrical circuit for four indoor units

This is the most concrete argument in favor of a multi-zone system in an older home, and it appears in black and white in the product specifications: the indoor units are powered by the outdoor unit. The interconnection cable carries both power and communications.

The practical consequence is considerable. Four independent wall-mounted units would require four dedicated circuits run to four rooms, through plaster walls and original floors, with four circuit breakers at the panel. Here, a single circuit, sized according to an MCA of 30 A and a maximum protection of 45 A, powers the entire system. In a village-core home where every wire run means work on historic materials, it is the difference between a clean installation and a week of plaster repairs.

The rule we explain before signing: one circuit, one mode

A multi-zone system shares a single refrigerant circuit among all its indoor units. This creates a limitation that we always state in writing before signing: all operating indoor units must be in the same mode. You cannot cool the south-facing bedroom while heating the north-facing office.

Each indoor unit has its own thermostat, temperature setpoint, and fan speed. One unit can be turned off while the other three are operating. But the mode—heating or cooling—is shared.

In practice, this limitation is rarely an issue in Quebec: in January, no one asks for air conditioning, and in July, no one asks for heating. It becomes noticeable in two specific situations that must be named: the shoulder seasons (April and October), and homes with highly contrasting orientations where a south-facing room overheats while the rest of the building still needs heat. A customer who learns this at the time of the quote accepts the trade-off without difficulty. A customer who learns it in October calls for service. It is the same information; only the timing changes.

This is also why, in highly contrasting homes, we sometimes propose a different combination: a multi-zone system for most rooms and a separate unit for the atypical room. It is not always as expensive as you might think.

The calculation few quotes show: the refrigerant charge

This is where a four-indoor-unit project differs technically from a single-indoor-unit project, and where mistakes cost the most in the long term.

The GWHD(36)ND6MO specification sheet indicates a factory charge of 2,700 g of R32 covering 40 meters of total piping, with an addition of 20 g per additional meter, up to a maximum total of 80 meters and a height difference of 25 meters.

Four indoor units distributed throughout a two-story house consume this allowance much faster than you might expect. Here is an example of a realistic layout in a house of this type:

The calculation then becomes:

53 m − 40 m covered by the factory charge = 13 m in excess
13 m × 20 g/m = 260 g of R32 to add
Final system charge: 2,700 + 260 = 2,960 g

This figure must be calculated, weighed on an electronic scale, and recorded in writing on the unit and in the file. This is not a formality. An undercharged multi-zone system heats poorly at the most distant indoor units, defrosts more often, and makes the compressor operate under unfavorable conditions. An overcharged multi-zone system loses efficiency and puts the compressor at risk. In both cases, the symptom the customer notices is identical: “the back bedroom is never comfortable.”

Two checks complete this calculation:

• Total length, compared with the permitted 80 m. At 53 m, there is still some margin; at 78 m, the layout must be reviewed or the zone distribution reconsidered.
• Vacuum evacuation, measured in microns with an electronic vacuum gauge, not by ear or by the clock. Four flared connections mean four potential leak points, and each one is tested.

One design detail simplifies this work: in this series, all connections use the same diameters—1/4 in. for liquid and 3/8 in. for gas, regardless of the head size. Less risk of selection errors, a single hardware format to prepare, and consistently executed flares.

How Capacity Is Distributed Among Four Zones

A question comes up with every multi-zone quote: “If I have four heads, does each one receive a quarter of the capacity?”

No. The outdoor unit modulates and distributes capacity according to the actual demand of each zone. The sum of the four heads' rated capacities usually exceeds the outdoor unit's nominal 36,000 BTU/h, and that is intentional: the four rooms never reach their peak demand at the same time. An upstairs bedroom reaches its peak at night, the living room in the evening, and the office during the day.

What this means, however, needs to be understood:

• When all zones are operating simultaneously at full demand, each receives less than its individual rated capacity. We therefore size the system according to the building's actual peak loads, room by room, rather than adding up the labels.
• When a single zone is operating, the modulation range becomes decisive. Heating capacity drops as low as 8,870 BTU/h: this lower limit determines whether a small bedroom will be comfortable or whether the unit will cycle constantly.
• The SEER 2 rating of 21 and HSPF 2 rating of 10 correspond to test combinations defined by the AHRI procedure. A real installation with a different assortment of heads does not automatically achieve these values. We present them as points of comparison between products, not as a promise about your energy bill.

A word about winter performance, which is what really matters on the South Shore: the heating range extends down to -30 °C, with smart defrost and automatic voltage adaptation—a feature that is not superfluous in a rural area where grid voltage can fluctuate.

Install four wall-mounted heads in a finished house without leaving a trace

The ceiling molding

In the photo, the unit is installed just below an untouched decorative ceiling molding. This is a matter of millimeters. A wall-mounted unit requires clearance above the cabinet for air intake and filter removal; molding reduces the available usable height.

There are three options, and we always present them in this order:

1. Lower the unit a few centimeters below the molding while maintaining the required clearance. This is the solution selected here, and visually the cleanest.
2. Notch the molding to recess the top of the unit. Quick, irreversible, and best avoided in an old house.
3. Move the unit to another wall. Sometimes the right answer, but it lengthens the route—which brings us directly back to the refrigerant charge calculation above.

The mounting-plate template is positioned with a laser and screwed into the structure, not just the plaster. A wall-mounted unit that is poorly anchored in an old wall will make itself known six months later through vibration.

Routing lines through plaster walls

The wall beneath the unit is intact and no line cover is visible. This requires a route planned in advance: drilling through the wall's actual thickness with a slight slope outward for the drain, installing a wall sleeve, sealing the building envelope both inside and outside, and routing the lines through an existing building cavity rather than through a structural element.

In a heritage home, this planning takes place before the work begins, not during it. We map the routes, confirm what is possible without demolition, and inform the client when a concealed route cannot be achieved—in which case a line cover becomes necessary and the client chooses with full knowledge rather than discovering it on the invoice.

Condensate

Every wall-mounted unit produces water in cooling mode. The preferred solution is always gravity drainage to the outside or to a drain, with a continuous, verified slope. When the room layout or wall thickness makes that impossible, we install a small condensate pump housed in a discreet enclosure beneath the unit, with a safety switch that stops the unit before any overflow.

On a four-head system, this point is multiplied by four. Four drainage routes to design, four slopes to verify, four points to document. This is precisely the kind of detail that a rushed installation overlooks and a stained ceiling reveals two summers later.

Room volumes and the A2L sensor

R32 is an A2L-classified refrigerant, mildly flammable, and this system contains approximately 2.9 kg in a single circuit shared by all four heads. This characteristic of a multi-zone system is important: the reference charge used to verify the rooms' minimum required area is that of the complete circuit, not that of an individual head.

The consequence is that the smallest room served becomes the project's control point. We measure it and compare it with the manufacturer's requirements before confirming the zone distribution. The installation height works in our favor—a high-wall-mounted head is more favorable than a floor-standing unit—and the system includes an A2L leak detection sensor as standard. These elements are part of the same approach: the unit provides the sensor, and the installer provides the verification.

The outdoor unit: 63 dB(A) in a village core

At 63 dB(A) at high speed, this outdoor unit is not discreet, and village lots are not always spacious. The location was therefore chosen based on four criteria: distance from bedroom windows, distance from the neighboring property line, clearance for airflow and the drainage of defrost water, and visibility from the street in a heritage-designated area. The unit is elevated to remain above the snow level and to prevent defrost water from accumulating beneath the base.

The mistakes we correct most often on multi-zone systems

1. Adding up the capacities of the heads instead of calculating the heat loss of each room. This method almost always results in oversizing.
2. Ignoring the refrigerant charge calculation. With four branches, the difference between the factory charge and the required charge is not insignificant.
3. Underestimating the total length and discovering at the end of the project that you're approaching the permitted 80 m.
4. Choosing a head that is too large for a small room, resulting in a unit that cycles instead of modulating.
5. Failing to explain the single-mode rule. This is the leading cause of dissatisfaction with a multi-zone system, and it is entirely avoidable with one sentence in the proposal.
6. Neglecting even one of the four drains. Three flawless drains and one sloppy one result in a sloppy system.
7. Failing to register the warranty. The 2 additional years are available only after registration with proof of installation.

Subsidies and warranty

The system is ENERGY STAR certified and bears reference code AHRI 214931589 in a ductless configuration—the exact reference required by subsidy programs to validate the declared performance. The ducted and mixed combinations using the same outdoor unit have different codes, which matters if one of the zones is served by a ducted unit rather than a wall-mounted head.

As for the warranty: 10 years of standard coverage, plus 2 additional years when the product is registered with proof of installation. We give the client the registration documentation at commissioning. Those two years of coverage are lost every time an installation is completed without this paperwork.

We confirm subsidy eligibility with the client before signing, with the technical file in hand, because the criteria and amounts vary from year to year and according to the system being replaced.

The result in Saint-Marc-sur-Richelieu

Four independently adjustable rooms, a single outdoor unit, a single 30 A electrical circuit, heating down to -30 °C, air conditioning in a home that had never had it, and intact plaster walls. The refrigerant charge was calculated, weighed, and recorded; the vacuum pull-down was measured in microns; all four drains were water-tested before the site was handed back; and the single-mode rule was explained and provided in writing.

This last point is what distinguishes a successful installation from one that is merely finished. A client who understands their system uses it correctly, and a system used correctly delivers the performance they paid for.

At AirGreen

We design and install 2- to 5-zone GREE FREEMATCH R32 multi-zone systems in Saint-Marc-sur-Richelieu, Saint-Charles-sur-Richelieu, Beloeil, Mont-Saint-Hilaire, and throughout the Richelieu Valley, as well as in Montreal, Laval, Longueuil, on the North Shore, and on the South Shore. Wall-mounted heat pumps, central heat pumps, air conditioners, air exchangers, HVAC installation, and HVAC maintenance: every project is measured, calculated, and documented before installation, including in older homes where aesthetics matter as much as performance. RBQ: 5645-9605-01.