A multi-zone installation where the roof support, snow, and the three refrigerant line runs matter just as much as the heat pump
This 3-head GREE Free Match R32 heat pump installation in Saint-Jude presents a configuration we regularly encounter when the outdoor unit cannot simply be placed at ground level: the unit was installed on a flat roof, on an elevated metal structure, itself positioned to protect the membrane and keep the heat pump high enough for Quebec’s winter conditions.
The site photograph clearly illustrates this approach. The GREE outdoor unit is installed on a rigid metal frame. Beneath this structure, long pieces of wood distribute the loads, while protective materials are placed between the load-bearing elements and the membrane. The lines from the different zones are grouped together and then routed horizontally across the roof.
This type of installation seems simple when looking only at the final result. In practice, a rooftop multi-zone heat pump requires our team to solve several problems simultaneously: how to distribute the weight properly, how to avoid damaging the roof, what height to maintain beneath the unit, how to manage vibrations, where to route three sets of lines, and how to maintain sufficient access for future HVAC maintenance.
In Saint-Jude, as elsewhere in Quebec, we must also think about what the installation will become in January and February, not just how it looks on a dry installation day.
An outdoor unit deliberately installed far from the membrane
The most striking element in the photo is the height of the support.
We did not want the bottom of the GREE unit to end up practically level with the roof. A heat pump used for heating It produces water during its defrost cycles. This water leaves the base of the unit and must be able to drain.
When the unit is installed too low, several problems can arise:
- Defrost water can freeze directly beneath the chassis;
- Ice can gradually rise toward the base of the heat pump;
- Snow accumulation can reduce clearances;
- Inspection beneath the unit becomes difficult;
- Debris on the roof can accumulate against the equipment.
The metal support visible in this project instead creates significant space beneath the outdoor unit. This height facilitates water drainage and provides more clearance for winter accumulation.
Why we do not simply try to install the unit as high as possible
A raised unit must remain stable.
The higher the center of gravity, the more attentive we must be to the support's rigidity, the machine's weight, and its exposure to wind. An open roof can receive gusts much more directly than a sheltered courtyard.
We are therefore seeking a balance: high enough to protect the heat pump, but on a structure stable enough to support it over the long term.
A roof-designed load distribution
The image shows that the support does not rest on four small points directly on the membrane. Long pieces of wood are used to distribute the loads over a much larger surface.
This is an important distinction.
A multi-zone outdoor unit can be relatively heavy. According to the technical table on page 2 of the Free Match R32 documentation, the models capable of accommodating three indoor units weigh approximately 112.5 lb to 174.2 lb, depending on their capacity.
This weight does not include only a stationary mass. During operation, we must also take into account:
- compressor vibrations;
- fan rotation;
- forces exerted by the wind;
- the temporary weight of a technician working around the unit;
- movement caused by temperature changes.
Protecting the membrane is therefore an integral part of theHVAC installation.
The isolators beneath the heat pump are not decorative
In the photograph, we can distinguish small isolators between the unit's feet and the metal rails.
Their role is to reduce vibration transmission between the chassis and the supporting structure.
On a roof, this detail can be particularly important. A relatively minor vibration can be transmitted to a structure and become audible indoors, especially when the unit operates at certain frequencies.
We use vibration-control devices as part of a more comprehensive strategy that also includes:
- a rigid base;
- a properly leveled support;
- stable supports;
- piping secured without excessive tension;
- a location offering sufficient space around the unit.
A pad cannot compensate for an unstable structure. It complements a properly designed installation.
Three heads, one outdoor unit: why this choice is worthwhile
The system GREE Free Match R32 allows several indoor units to be connected to the same outdoor unit.
In this project, this is a configuration 3 heads, making it possible to create three comfort zones in the building without installing three separate condensers on the roof.
This advantage is particularly significant in a project where the outdoor unit must be installed on the roof. Three completely independent systems would have required more:
- occupied space;
- supports;
- electrical circuits;
- pipe runs;
- equipment to maintain on the roof.
With the multi-zone system, a single outdoor unit centralizes the operation of the three zones.
Which GREE Free Match R32 outdoor units support three indoor units?
The exact number visible in the photograph is not clear enough for us to assign a precise capacity to this installation.
We do not want to make up a figure.
However, the GREE technical table lists several outdoor units compatible with three indoor units:
- GWHD(24)ND6MO : 2 to 3 indoor units, 24,000 BTU/h rated cooling and 24,000 BTU/h heating;
- GWHD(30)ND6MO : 2 to 4 units, 28,400 BTU/h cooling and 30,000 BTU/h heating;
- GWHD(36)ND6MO : 2 to 4 units, 36,000 BTU/h cooling and heating;
- GWHD(42)ND6MO : 2 to 5 units, 42,000 BTU/h cooling and 44,300 BTU/h rated heating.
A three-head installation therefore does not automatically correspond to a 30,000 or 36,000 BTU/h heat pump.
Why we never size the system solely according to the number of heads
Three indoor units can serve three small bedrooms or, conversely, a large open-concept area and two rooms with significant thermal loads.
The difference is considerable.
For proper selection, we examine, among other factors:
- space area;
- ceiling height;
- insulation;
- number of exterior walls;
- fenestration;
- sun exposure;
- room usage;
- the likelihood that all three zones will require substantial capacity simultaneously.
Nor should the sum of the capacities listed for the indoor units be interpreted as the power the outdoor unit can continuously provide to each one. The outdoor heat pump distributes its capacity among the active zones.
Efficiency of up to 21 SEER2
The documentation for the GREE Free Match R32 indicates efficiency of up to 21 SEER2, 12.5 EER2 and 10 HSPF2. It also states a cooling range of -30 °C to 48 °C.
For heating, the published operating range is -30 °C to 24 °C.
This data is particularly relevant for a heat pump installed in Saint-Jude, where the system must get through an entire Quebec winter.
However, two concepts must be distinguished: being able to operate at a given temperature and providing its full rated capacity at that same temperature are not necessarily the same thing.
That is why our analysis never stops at the statement “heating down to -30 °C.”
G10 modulation is particularly useful with three zones
GREE documentation mentions a G10 inverter technology, intelligent defrosting, self-diagnostics, automatic voltage adaptation, and quiet operation. Up to seven types of indoor units are also available for this platform.
This modulation capability is particularly useful for a three-zone heat pump.
The three rooms almost never require exactly the same amount of heating or cooling at the same time.
A sunny room may quickly reach its setpoint while another remains calling for heating or cooling. The inverter compressor can adjust its operation to better follow this variable load.
Three zone thermostats do not mean three opposing modes
Each indoor head has its own temperature setting. This is one of the major advantages of a multi-zone system.
For example, occupants can set a bedroom to a different temperature from the main room.
However, it is important to keep in mind that the units share the same outdoor unit. In this multi-zone configuration, the three zones normally operate in the same general mode.
We therefore recommend avoiding conflicting demands in which one head is set to heating while another simultaneously requests cooling.
What this Saint-Jude installation teaches us about the details that make a multi-zone heat pump last
The route of the lines is particularly important on a roof
On the left and behind the outdoor unit, the photograph shows the grouping of the lines leaving the heat pump and continuing across the roof.
With three heads, we must organize several circuits without creating a vulnerable tangle of piping.
The lines must be:
- protected from UV rays;
- kept free of excessive tension;
- properly insulated;
- supported along their route;
- organized so that a technician can identify each zone;
- protected from areas where people might walk.
A refrigerant line is not simply “hidden” after installation. Accessibility remains important throughout the system’s entire service life.
Significant lengths are possible, but they must be calculated
Page 2 documentation provides the piping limits for each outdoor unit.
For models supporting three indoor units, the maximum total length varies by capacity, ranging from 197 ft (60 m) to 328 ft (100 m). The maximum elevation difference increases from 49 ft (15 m) to 82 ft (25 m) depending on the selected outdoor unit.
This flexibility is useful when the outdoor unit is on the roof and the three heads are distributed in different areas of the building.
It does not mean that we deliberately seek the longest routes.
Our goal remains to reduce detours to simplify:
- commissioning;
- insulation protection;
- future service work;
- identifying the three circuits.
1/4 in. and 3/8 in.: the published connection sizes for the product range
The same sheet indicates an outside diameter of 1/4 in. for the liquid line and 3/8 in. for the gas line in the table for this product range.
Before any installation, we always validate the requirements specific to the exact combination and the installed indoor units.
On a multi-zone installation, a piping error can be particularly costly to correct once all three runs are complete.
The refrigerant precharge varies by outdoor unit
Another interesting detail in the technical table: the piping lengths covered by the initial charge are not identical from one outdoor unit to another.
The documentation indicates precharge lengths ranging from 33 ft to 164 ft depending on the model, as well as an additional charge published for lengths requiring adjustment.
In a three-head installation, we therefore need to know the actual length of the branches.
A rough estimate quickly becomes problematic when three different runs are added together.
Evacuation and leak testing remain critical steps
Once the lines are installed, our work does not consist of immediately opening the valves and starting the unit.
We must first ensure that the circuits are leak-tight and contain no moisture or unwanted air.
The procedure includes, in particular:
- checking the connections;
- leak testing;
- evacuating the system;
- validating the lengths of each circuit;
- adjusting the charge if required;
- checking communications;
- testing all three zones.
On a three-head system, every branch matters. A leak in a single line can affect the operation of the entire outdoor unit.
R32 requires adapted practices
The Free Match R32 uses R32 refrigerant. GREE documentation also mentions a integrated A2L leak detection sensor.
This means working with the methods, tools, and procedures appropriate for this platform.
The choice of a modern heat pump should therefore never be separated from the quality of its installation. Factory performance can only be properly reproduced in the field if the refrigeration circuits, electrical work, and commissioning are carried out according to the applicable requirements.
Electrical requirements vary significantly between capacities
All outdoor units in the table operate at 208/230 V, but the electrical requirements are not identical.
For models that can power three heads, the table indicates a MCA between 19.5 and 30 A and maximum overcurrent protection ranging from 25 to 45 A depending on the model.
This point is worth emphasizing: the number of heads alone never determines the electrical circuit rating.
We check the actual outdoor unit installed and its nameplate data before finalizing the power supply.
Why roof access must remain clear after we leave
A heat pump must not be installed as if no one would ever need to work on it again.
A technician may eventually need to:
- remove the panels;
- access the valves;
- check the wiring;
- clean the heat exchanger;
- measure certain operating conditions;
- to inspect the condition of the lines;
- to work on the fan or compressor.
In the Saint-Jude photograph, the outdoor unit remains surrounded by open space. This is exactly what we look for when a roof gives us this opportunity.
What not to install around the heat pump after the work
Over time, a roof may receive new elements: furniture, materials, telecommunications equipment, panels, ducts, or other technical installations.
We recommend maintaining clearances around the heat pump and not using its base as storage space.
Particular care must be taken to avoid:
- to lean objects against the grille;
- to place a solid screen directly in front of the fan;
- to cover the lines with heavy materials;
- to block the space beneath the unit;
- to move the protective materials under the supports without an assessment.
Outdoor maintenance is different when the unit is not visible every day
A heat pump installed in a yard is often observed daily by occupants. A rooftop unit may go several months without being inspected.
That is why periodic inspection is even more important.
We check, in particular:
- the cleanliness of the heat exchanger;
- the condition of the fasteners;
- the stability of the support;
- the vibration isolators;
- the insulation on the lines;
- any accumulation of ice;
- the presence of debris around the unit;
- the overall integrity of the roof area.
Indoors, the three heads also require their own filter cleaning.
Sound level: the support is part of the equation
The technical table on page 2 indicates, depending on the outdoor unit, high-speed sound pressure levels ranging between 58 and 63 dB(A) for models that can accommodate three heads.
However, a laboratory value alone cannot predict what will be heard in the building.
Vibration transmission also depends on:
- the roof structure;
- the support;
- the position of the unit;
- the isolators;
- the proximity of occupied rooms.
This is one of the reasons why the design of the base visible in this installation is just as important as the choice of the unit itself.
AHRI, ENERGY STAR, and rebates: always verify the complete combination
The table on page 2 does not provide a single AHRI number for the entire range. It lists separate references according to capacity and whether the combination is ductless, ducted, or mixed.
The documentation also indicates that these units are eligible for local rebates.
However, we cannot infer a precise amount for the Saint-Jude project from this brochure alone.
Any request for financial assistance must be based on:
- the exact outdoor model;
- the three indoor units actually installed;
- the AHRI number for this combination;
- the applicable program;
- the criteria specific to the building and the applicant.
This avoids unpleasant surprises after installation.
A warranty that must be registered and documented
The GREE sheet indicates a 10-year standard warranty, as well as an additional two-year extension with Wolseley when the product is registered and/or proof of installation is provided.
We always recommend keeping the following with the heat pump file:
- the invoice;
- the outdoor model;
- the models of the three heads;
- the serial numbers;
- the AHRI number;
- the registration records;
- the documents applicable to the warranty.
The coverage for the rooms must also be distinguished from the labor warranty conditions.
The mistakes this rooftop installation helps avoid
Placing the heat pump too close to the membrane
This leaves little room for snow, ice, and drainage.
Concentrating all the weight on four small points
On a rooftop, load distribution and membrane protection must be carefully considered.
Forgetting about vibrations
A heat pump may be quiet in the air yet transmit vibrations through a poorly designed base.
Leaving the lines exposed in a traffic area
The three lines must be organized and protected.
Choosing a capacity simply because there are three heads
The load calculation remains essential.
Confusing operation at -30 °C with full capacity at -30 °C
The operating range alone does not represent the capacity available during a cold snap.
Promising a rebate without verifying the AHRI number
The exact combination of equipment is decisive.
An AirGreen installation where the support is part of the HVAC system
This Saint-Jude clearly shows that a professional installation is not limited to the brand displayed on the front panel.
The GREE Free Match R32 provides multizone technology, an inverter compressor, and the ability to power several indoor units. But actual performance also depends on everything around it: sizing, piping, refrigerant charge, electrical work, drainage, access, and, in this case, a rooftop base designed to properly support the unit.
The photograph precisely captures this part of the work. The heat pump is installed high up on a metal frame. Its load is distributed across long bases. Protective barriers separate the installation from the roof surface. The circuits are grouped together, and the fan retains ample clearance in front of it.
At AirGreen, we apply the same approach to our heat pumps, wall-mounted air conditioners and systems HVAC to Saint-Jude, as well as in Montreal, Laval, Longueuil, on the North Shore and on the South Shore.
The desired result is not simply a heat pump that works on the day it is commissioned. We want an installation that remains stable, accessible, serviceable, and suited to Quebec’s realities after several heating and cooling seasons.