Installation of a 3-head GREE FreeMatch R32 heat pump on a flat roof in Rougemont, Montérégie

In Rougemont, three indoor zones connected to a single outdoor unit installed on the roof

This installation of a 3-head GREE FreeMatch R32 heat pump in Rougemont immediately stands out because of the location of the outdoor unit. Rather than occupying ground-level space near the building, the unit was installed on a flat roof, amid an environment that already includes several vents, technical outlets, and rooftop elements.

The project photograph shows part of the work that usually disappears once the finishes are complete: the technical side of the GREE unit, the various networks connected to it, the insulated lines associated with the indoor zones, the wiring, and the structure supporting the machine.

The outdoor unit is installed on a raised metal support, positioned above a protective base and visible wooden supports on the roof. This configuration creates space beneath the unit and avoids placing the heat pump directly on the roof surface. On the side of the unit, several refrigerant lines converge at the multi-zone system connections.

The safety label visible on the side panel also clearly identifies the R32 and its A2L classification, an important detail since the refrigerant type influences the work methods, tools, and commissioning procedures.

For us, this project nicely sums up the logic of a multi-zone heat pump : indoors, three separate spaces must receive adapted comfort; outdoors, all this equipment converges into a single unit that must be positioned, connected, and properly protected.

Why place the outdoor unit on a flat roof?

The best location for a heat pump is not necessarily the one closest to the ground. Depending on the building’s architecture, the location of the three indoor heads, and the available routes for the lines, a rooftop installation can offer a much more coherent configuration.

In this project in Rougemont, the roof notably makes it possible to concentrate technical routes in an area away from ground-level circulation spaces.

This installation can offer several advantages:

• reduced clutter around the building;
• a more logical route to units located on upper floors;
• protection against certain accidental impacts at ground level;
• preservation of outdoor paths, walkways, and landscaping;
• the possibility of grouping several mechanical components in a technical area;
• direct access to the outdoor unit connections for maintenance.

But a roof also imposes its own constraints. The membrane, weight, drainage, winter accumulation, airflow, and technician access must all be considered.

This is precisely why a rooftop installation must be planned as a whole, rather than as simply moving the heat pump to a higher location.

A raised machine to leave space beneath the outdoor unit

In the photograph from Rougemont, the GREE unit does not rest directly on the roof. It is installed on a metal structure that keeps the cabinet at a certain height.

This space beneath the machine is especially useful in heating mode.

When a heat pump operates in cold weather, frost can form on its outdoor coil. The system then periodically performs a defrost cycle. The ice melts and produces water that must be able to drain beneath the unit.

In winter, a machine positioned too close to a surface can gradually become surrounded by ice buildup. On a Quebec roof, snow, freeze-thaw cycles, and the way water moves toward roof drains must also be taken into account.

The documentation for the GREE FreeMatch R32 announces a heating range of up to −30 °C, with an air-conditioning range of −30 °C to 48 °C.

An installation designed to operate during the winter must therefore be planned from the outset for these conditions, rather than only for air-conditioning days in July.

Protecting the roof during and after the work

A flat roof requires more precautions than a concrete slab at ground level.

During installation, copper lines, tools, fasteners, and metal parts must be handled without damaging the membrane. A small screw left beneath a base or a sharp object dragged across the roof can create a problem unrelated to the heat pump’s operation but that can become costly for the owner.

On this project, we pay particular attention to:

1. protecting the surface beneath the structure;
2. the stability of the support;
3. weight distribution;
4. the absence of loose metal parts on the roof;
5. preserving water drainage paths;
6. access to the technical equipment already present on the roof.

Once the work is complete, the roof must remain usable by roofers, electricians, and HVAC technicians who may need to work there in the future.

Several lines are visible on the side of the unit: the reality of a three-head system

The photo makes it easy to understand why a three-head heat pump requires more planning than a single-zone system.

Several insulated lines converge toward the side of the outdoor unit. Behind their relatively compact appearance are the connections required for the various indoor units.

For each of the three zones, we must plan:

• the refrigerant circuit;
• communication wiring;
• the power supply specified in the system design;
• the drainage route for the indoor head;
• pipe insulation;
• the passage through the building;
• proper circuit identification.

These routes must be organized before they reach the roof. A three-head installation quickly becomes difficult to troubleshoot if the piping is not clearly associated with the correct indoor units.

Why we identify the circuits before commissioning

On a multizone system, a mismatched connection can create a particular situation: the wiring for head A may be connected to the correct electrical port while its refrigerant circuit reaches port B.

The system then receives information that does not correspond to the zone actually being supplied.

To avoid this type of problem, we identify the three routes before the final connection, then check each head individually during commissioning.

This method confirms:

• that head 1 communicates with its circuit;
• that head 2 corresponds to its connection;
• that head 3 is correctly associated;
• that each unit responds to its own control;
• that multiple zones can operate together without problems.

Piping lengths that must be calculated as a whole

One of the common errors in a multizone installation consists of looking only at the distance between the outdoor unit and the farthest head.

The manufacturer also requires a maximum total length.

The technical table on page 2 of the GREE specifications indicates, depending on the outdoor model, a total length of up to 100 m. For outdoor units compatible with three indoor units, the published values include 60 m for the GWHD(24), 80 m for the GWHD(30) and GWHD(36), and 100 m for the GWHD(42).

For a rooftop project, we must also consider the height differences between the outdoor unit and the indoor units.

The same table indicates a maximum elevation difference of 15 m for certain models and up to 25 m for higher-capacity outdoor units.

This makes documenting the routes particularly important when the three heads are distributed across multiple levels.

R32 refrigerant: a charge that must be measured, not improvised

The GREE specifications indicate precharged lengths that vary according to the outdoor model, as well as an additional charge of 20 g/m when the system length exceeds the value covered by the factory charge.

In a three-head installation, a few additional meters on each branch can quickly represent a significant total length.

Therefore, we must:

• measure each route;
• add the three lengths;
• know the selected outdoor unit’s precharge length;
• calculate the amount of R32 to add when required.

Adding refrigerant based on a mere impression or solely on a pressure observed momentarily is not the right approach.

The system is designed around a precise amount of refrigerant corresponding to the actual system configuration.

An A2L-classified R32 refrigerant that requires an appropriate procedure

The wording A2L R32 appears directly on the label of the unit visible in the photograph.

The product-range documentation also mentions an A2L leak-detection sensor included among the system’s functions. It also indicates self-diagnostics, intelligent defrosting, G10 Inverter technology, and automatic voltage adaptation.

However, the presence of a sensor never replaces a properly executed refrigeration installation.

Before putting the system into operation, we carry out essential steps:

1. preparing the copper ends;
2. making the connections;
3. checking the tightness;
4. leak testing;
5. evacuating the system;
6. verifying that the vacuum holds;
7. calculating the additional charge;
8. opening the valves;
9. final connection check.

These operations are much less visible than the outdoor unit itself, but they directly affect system reliability.

Performance, sizing, and practical advice for a three-head GREE FreeMatch R32 system

Not all GREE FreeMatch R32 units have the same capacity

The photograph clearly shows a GREE outdoor unit, but the nameplate is not legible enough to reliably confirm its exact reference.

We therefore do not arbitrarily assign it a BTU rating.

However, the technical data sheet on page 2 indicates which units in the range can be used in a three-zone configuration:

• GWHD(24)ND6MO : 2 to 3 indoor units;
• GWHD(30)ND6MO : 2 to 4 units;
• GWHD(36)ND6MO : 2 to 4 units;
• GWHD(42)ND6MO : 2 to 5 units.

The corresponding rated cooling capacities are, respectively, 24,000 BTU/h, 28,400 BTU/h, 36,000 BTU/h, and 42,000 BTU/hFor heating, they are 24,000, 30,000, 36,000, and 44,300 BTU/h.

This shows why it would be incorrect to automatically associate “three heads” with a specific BTU rating.

The outdoor unit must be sized according to the three actual zones

We do not select a multi-zone heat pump simply by adding up the capacities listed on the indoor units.

Each room has its own thermal load.

We analyze in particular:

• the floor area;
• the amount of glazing;
• the building’s orientation;
• sun exposure;
• insulation;
• air infiltration;
• the number of exterior walls;
• the ceiling height;
• the floor where the area is located;
• the room’s daily use.

A room with little sun exposure does not require the same capacity as a large open-plan area with several windows.

In Rougemont, as in our projects in Montreal, Laval, Longueuil, on the North Shore and the South Shore, so proper sizing consists of balancing three indoor needs around the actual capacity of a single outdoor unit.

Capacity is shared when multiple heads operate together

In a FreeMatch system, the three indoor units do not each have their own compressor.

They all use the outdoor unit shown in the photo.

When only one zone calls for heating or cooling, the system can adjust its output to that demand. When all three heads place a heavy demand on the unit at the same time, the available capacity is distributed among the active zones.

This characteristic is important when sizing the system.

A combination may appear highly efficient when only one head is operating and reveal its limitations only when several spaces simultaneously require substantial heating on a cold night.

Up to 21 SEER2: understanding the figures correctly

The FreeMatch R32 lineup documentation advertises efficiency of up to:

• 21 SEER2;
• 12.5 EER2;
• 10 HSPF2.

The technical table on page 2 also indicates a SEER2 of 21 and an HSPF2 of 10 for the listed outdoor units.

These values are relevant for a system designed to provide both cooling and heating.

However, they must be considered in the context of the combination actually installed.

Practical performance also depends on:

• the length of the lines;
• the refrigerant charge;
• the outdoor temperature;
• filter maintenance;
• the cleanliness of the outdoor heat exchanger;
• the number of active heads;
• the settings selected by the occupants.

A good unit cannot compensate for a poorly executed installation.

G10 Inverter technology: particularly useful when there are three zones

GREE documentation identifies the technology G10 Inverter among the features of the FreeMatch R32.

This type of operation is well suited to a multi-zone heat pump because demand changes continuously.

For example, three zones may be heating early in the morning. Once the bedrooms reach the desired temperature, only one living area may continue to call for heat.

The compressor can then adjust its operation to the load instead of constantly running at maximum capacity.

This modulation helps stabilize temperatures and better track the varying needs of different rooms.

The three heads remain independent in terms of temperature, but not in terms of the overall mode

Each indoor unit can have its own setpoint temperature.

However, a conventional multi-zone system shares the same outdoor refrigeration cycle. The three units therefore generally operate in the same primary mode: heating or cooling.

It is normally not possible to request simultaneously:

• of heating in a bedroom;
• of cooling in another zone.

This situation occurs mainly during the shoulder seasons, when a very sunny room warms up while another part of the building remains cool.

We explain this operation when handing over the system to prevent users from thinking that one head has a problem when it is simply waiting for a command compatible with the general mode.

Electrical requirements vary by outdoor unit

All FreeMatch outdoor units shown in the table use a power supply 208/230 V, but the maximum electrical protection varies according to their capacity.

Among the models that can accommodate three heads, the specification sheet indicates:

• GWHD(24): MCA 19.5 A / MOCP 25 A;
• GWHD(30): MCA 23 A / MOCP 35 A;
• GWHD(36): MCA 30 A / MOCP 45 A;
• GWHD(42): MCA 30 A / MOCP 45 A.

This means that two three-head GREE installations may require different electrical circuits.

We therefore always use the nameplate of the actual outdoor unit installed rather than a general rule based solely on the number of indoor units.

Access to the fittings must remain possible after finishing

The photograph from Rougemont shows the technical side of the outdoor unit, with the connections still readily accessible.

This access must not disappear after installation.

A technician must eventually be able to:

• check the pressures and temperatures;
• inspect the connections;
• check the watertightness;
• access the electrical panel;
• clean the heat exchanger;
• diagnose an indoor unit;
• perform a HVAC maintenance.

Installing an outdoor unit too close to an obstacle simply to save a few centimeters can make a future service call much more complicated.

On a roof where several vents and pieces of equipment are already present, we must think about the technician who will return several years from now, not just the person carrying out the installation today.

Errors we want to avoid when installing a three-head rooftop system

Underestimate the three pipe lengths

The total network must be measured and compared with the manufacturer's limits.

Install the unit without considering defrost water

A heat pump operating down to very low temperatures must be able to drain the water produced during its winter cycles.

Fail to adequately protect the roof

HVAC work must not cause a membrane or drainage problem.

Cross-connect the circuits of the different heads

Each refrigerant circuit and its wiring must remain correctly associated.

Close the conduits before completing the tests

We keep critical areas accessible until the watertightness and operation have been validated.

Choose the circuit breaker according to the number of heads

Electrical protection depends on the exact outdoor unit, not simply on the fact that it is a three-zone system.

Adding R32 without calculating the line length

The additional charge is determined according to the system actually installed.

AHRI, ENERGY STAR, and rebates: use the correct combination

The technical table on page 2 provides distinct AHRI numbers for non-ducted, ducted, and mixed combinations. It also includes an ENERGY STAR designation for listed equipment.

For a grant or rebate application, we must use the reference corresponding to the combination actually installed.

The name GREE FreeMatch R32 alone is not sufficient.

The indoor unit and outdoor unit models must match the certified combination.

The documentation also mentions a standard 10-year warranty as well as the possibility of a two-year extension with Wolseley when the registration and/or proof-of-installation requirements are met. It also indicates possible eligibility for local rebates.

Financial assistance conditions may change. We therefore always verify the applicable criteria at the time of the project rather than promising an amount based solely on the product name.

An installation in Rougemont where the essentials also lie in what will no longer be visible

The photograph of this GREE FreeMatch R32 installation in Rougemont shows a particularly revealing stage of the project.

The outdoor unit is in place on its support, but the various technical routes remain visible. The insulated lines, the unit's service side, the wiring, and the way the different networks run toward the building can be seen.

Once the finishing work is complete, these elements attract far less attention.

Yet these are precisely the elements that determine much of the installation's quality:

• the correct indoor units matched with the correct outdoor unit;
• compliant lengths;
• properly insulated lines;
• a calculated amount of R32;
• a leak-tight system;
• a properly performed vacuum evacuation;
• clearly identified circuits;
• an accessible outdoor unit;
• a protected roof;
• validated operation across all three zones.

At AirGreen, this is the approach we apply to our heat pump, of wall-mounted air conditioner andHVAC installation, whether the outdoor unit is installed on the ground, on a balcony, or, as here, on a flat roof.

In Rougemont, GREE FreeMatch R32 three-head system allows three indoor zones to be centralized around a single outdoor unit. For the homeowner, the end result is a more discreet multi-zone system around the building. For us, success is also measured by the quality of the entire technical installation between these three indoor units and the unit installed on the roof.