Installation of a GREE UNIX R32 central heat pump in Saint-Simon, in the Les Maskoutains RCM

The photo shows the vacuum pump running: this is the most critical step of the job, and the one nobody photographs.

A homeowner from Saint-Simon, in the Les Maskoutains RCM, called us to replace a central system at the end of its service life. The ductwork was in good condition, the electrical service was adequate, and the outdoor location along a concrete-block wall was clear. On paper, it was a straightforward job.

It's precisely on this kind of job that the difference between two contractors isn't visible at the time of signing. You see it seven years later, when a compressor fails for a reason no one understands.

We installed a GREE UNIX R32 central heat pump there. Here are the two decisions that really mattered: the indoor configuration selected and the rigor of the commissioning process.

Two ways to install a UNIX R32, and a performance difference that few people quantify

This is the most useful piece of information in the entire article, and it applies to any central heat pump project in Quebec.

The UNIX R32 series can be installed in two ways:

• A) With a UNIX R32 air handler — a complete air-handling unit with its own blower.
• B) With a UNIX R32 cabinet coil — a coil added to an existing furnace as a retrofit, reducing labor and equipment costs.

Option B is regularly presented to customers as “the same thing, but cheaper.” It isn't the same thing. Here are the figures published by GREE for the 60,000-size model, using the same outdoor unit:

A difference of 3.3 TRÉS2 points and 2.0 CPSC2 points, for the same outdoor unit and the same house.

This is not a catalog subtlety. It is a difference in consumption that is paid for every month throughout the system's entire service life. And because Hydro-Québec's financial assistance is tied to the AHRI code for the exact combination installed, changing the indoor unit changes the file number, and therefore eligibility and the amount. We systematically validate the exact combination in Hydro-Québec's search tool before ordering the equipment.

When a cased coil remains the right choice

We do not reject option B. It is entirely justifiable in three situations:

1. The existing furnace is relatively new and in excellent condition, and replacing it makes no economic sense.
2. The dual-fuel configuration is selected, and the fuel-fired appliance must remain in place as the backup heat source.
3. The available budget does not allow for option A, and the real choice is between a cased coil and no heat pump at all.

What we refuse to do is present option B as equivalent. In Saint-Simon, the existing system was nearing the end of its useful life: replacing the blower at the same time as the rest cost little more than keeping it, and delivered more than three additional points of HSPF2. Option A was the obvious choice.

The selected equipment

Ultra Heat and Ultra Cool: the figures behind the names

These two terms are widely used but rarely defined. GREE quantifies them precisely:

• Ultra Heat: 100% heating capacity at -20°C, with stable operation down to -30°C.
• Ultra Cool: 100% cooling capacity at 46°C, with stable operation down to 48°C.

The first line is the one that matters in Montérégie. “100% of capacity at -20 °C” means that the unit still delivers its full rated output at a temperature where most air-source heat pumps have already lost 40 to 50% of theirs.

This does not mean that the unit delivers 54,000 BTU/h at -30 °C: at that temperature, it operates steadily but with reduced capacity. The difference between “operates” and “delivers its full capacity” is exactly what we detail in the quote, because it determines whether supplemental heating is needed and what size it should be.

The two-stage, two-cylinder compressor

The UNIX R32 series uses DC Inverter technology with a two-stage, two-cylinder compressor.

In practical terms, for the homeowner:

• The modulation range is very wide: from 35,000 to 60,000 BTU/h in heating mode for this format. The unit runs continuously at low output rather than starting and stopping.
• Comfort is more stable. A modulating system maintains the setpoint without the temperature swings produced by an on-off unit.
• Noise is lower most of the time. The outdoor unit's 62 dB(A) corresponds to maximum operation, which is rarely reached.
• Drying is better in summer. A coil that stays cold for a long time removes more moisture than one that cools intermittently.

Commissioning: what the photo shows

In the photo from this job, we can see the gauges connected to the service valves and the vacuum pump running at the base of the unit. This is the step that determines the compressor's service life, and it is the one most readily shortened when the day is long.

Why evacuation is non-negotiable on an R32 system

Residual moisture in a refrigeration circuit combines with the compressor's POE oil and forms acids. These acids attack the winding insulation varnish. Failure does not occur in the first year: it occurs five, six, or eight years later, and the diagnosis rarely traces back to the true cause.

Our sequence:

1. Connection to the external service valves. The UNIX series places the service valves and electrical terminals outside the cabinet, making this step faster and cleaner.
2. Dry nitrogen pressure test before any evacuation, to validate the tightness of the flared connections.
3. Evacuation below 500 microns, measured with an electronic micron gauge—never with service gauges, which simply do not reach low enough to be meaningful.
4. Closed-valve standing test of at least 15 minutes. A rise that levels off indicates a leak; a rise that continues climbing without stopping indicates residual moisture.
5. Opening the valves and weighing in the additional charge on an electronic scale. The unit is precharged for 24.6 ft (7.5 m) of piping; beyond that, the charge is calculated and weighed, not estimated.

Design limits: 98.4 ft (30 m) maximum length, 49.2 ft (15 m) maximum elevation difference, 3/4 in. suction line, and 3/8 in. liquid line.

Airflow, measured rather than assumed

The air-handling cabinet is rated at 1,500 CFM at 125 Pa (0.5 in. w.c.) of nominal external static pressure.

This last value is the one almost nobody checks, and it is the most revealing. A ductwork system designed for an older furnace often operates well above 0.5 in. w.c. In that case, the actual airflow collapses below the nominal value, capacity follows, and the customer ends up with a 54,000 BTU/h unit that delivers significantly less.

We therefore measure the external static pressure on both sides of the cabinet during commissioning and correct the ductwork when necessary. At Saint-Simon, the existing ductwork handled the load after two secondary branches were reworked.

The support and the disturbed ground

The unit rests on a steel support with adjustable feet, placed on load-distribution pads. This raises it far enough off the ground for defrost water to drain freely in winter and prevents any ice buildup from reaching the coil.

The ground around the unit had been disturbed during the work. This is a detail worth following up on: fresh backfill settles over the following months, and a support placed on settling ground loses its level. A unit that is no longer level can no longer drain its pan properly.

So we revalidate the level during the follow-up visit, before the first winter. It is five minutes of work that prevents an intervention in February.

What a commissioning should leave you with in writing

A homeowner who receives no documentation after installation has no way to know whether the work was done correctly. Here is what should be included in your file, and what we consistently provide:

• The actual piping length and the exact weight of refrigerant added beyond the factory charge.
• The vacuum level reached and the result of the hold test.
• The superheat and subcooling readings under steady-state conditions.
• The measured external static pressure on both sides of the air handler.
• The AHRI code for the installed combination — essential for the financial incentive application.
• A photo of the outdoor unit’s nameplate, with the model and serial numbers legible.
• The selected balance point and the control logic for the auxiliary heat.

Without this data, the next technician who services your system is working blind, and you pay for the time needed to reconstruct it.

What the UNIX R32 series makes easier to service

Three design features have a direct effect on the cost of future service calls:

• Service valves and external electrical terminals eliminate the need to open the cabinet for routine work.
• Compatibility with standard 24 V wired thermostats means you are not locked into a proprietary thermostat. The series also supports RS485 communication for configurations that require it.
• Compatibility with downflow applications enables installation configurations that many central systems do not support, which matters in homes where the air handler must be installed above the supply ductwork.

The refrigerant leak detector is included on all GREE Canada air handlers and cased coils. Because R32 is a mildly flammable refrigerant, this detection is an integral part of the equipment, and its position must be respected during installation.

Seven errors we regularly correct

1. Choosing a cased coil without explaining the performance gap compared with a complete air handler.
2. Estimating the refrigerant charge from the gauges instead of weighing it.
3. Settling for a vacuum reading that “looks good” without a micron gauge or hold test.
4. Failing to measure external static pressure on an existing ductwork system.
5. Confusing the operating range with available capacity at low temperatures.
6. Installing a support on fresh fill without rechecking the level after settling.
7. Providing an invoice without the AHRI code, which blocks the financial assistance application.

Where we work

Our teams serve the Les Maskoutains RCM — Saint-Simon, Saint-Hyacinthe, Saint-Damase, Saint-Liboire, Sainte-Hélène-de-Bagot, Saint-Hugues, La Présentation — and all of Montérégie, as far as Sorel-Tracy, Granby, and Saint-Jean-sur-Richelieu.

We carry out the same central heat pump installations throughout the South Shore — Longueuil, Boucherville, Brossard, Saint-Hubert — in Montréal, in Laval, and on the North Shore, from Terrebonne to Saint-Jérôme.

The Saint-Simon homeowner had a competing quote for a cased coil, presented as equivalent. After seeing the two tables side by side, his response was brief: “No one had shown me this.”

Let's move forward with your project

If your central system is nearing the end of its service life, if you are comparing quotes that appear to offer the same thing at different prices, or if you simply want to know what your existing ductwork can actually support, the answer starts with a survey and measurements.

At AirGreen, every HVAC installation project includes a load calculation, a survey of the existing ductwork, a quantified comparison of possible configurations, AHRI code validation for financial assistance programs, and a commissioning report provided to the customer. Contact us for your project in Saint-Simon, in the Les Maskoutains RCM, in Montérégie, on the South Shore, in Montréal, in Laval, in Longueuil, or on the North Shore.