Installation of a 5-ton GREE FLEXX R32 central heat pump (10.5 CPSC2) in Saint-Aimé, Pierre-De Saurel RCM

A central heat pump in a service yard: half the work takes place around the unit

The equipment was the same as on many other jobsites. The environment was not: a service yard behind the building, a concrete block wall marked by decades of runoff, wooden pallets leaning one metre from the planned location, a container, and vegetation reclaiming the area every summer. This is exactly the kind of setting where a properly selected central heat pump delivers poor results—not because of the unit, but because of what surrounds it.

We installed a five-ton GREE FLEXX R32 system in Saint-Aimé, in the Pierre-De Saurel RCM in Montérégie: an outdoor unit, GUD60W2/NhE-D(U), and an indoor unit, GUD60AH2/G-D(U). Here is what actually occupied our day.

Saint-Aimé: a heating context, not a cooling context

Saint-Aimé is a small agricultural municipality in the Sorel-Tracy area, on the Yamaska River plain. Two characteristics of the area shape the entire design of an HVAC system:

• Heating dominates the bill, by far. In a typical year in rural Montérégie, heating hours far outnumber cooling hours. A unit chosen solely for its cooling efficiency is the wrong choice for this area.
• The building is often old and spacious. Homes expanded over generations, high ceilings, added wings, and a varied building envelope. The calculated loads are higher there than in the suburbs of Longueuil or Laval for a comparable area.

This reasoning led us to choose the largest configuration in the lineup rather than the four-ton model.

The selected pairing: GUD60W2/NhE-D(U) and GUD60AH2/G-D(U)

The only model in the lineup at 10.5 CPSC2

This is the point we want to emphasize because it goes against the usual instinct. In the FLEXX range, the 54,000 BTU/h configuration does not have the best TRÉS2—it is rated at 18.5, compared with 19 for the four-ton unit. On the other hand, it is the only one to reach 10.5 CPSC2, while the other three top out at 10.

CPSC2 (HSPF2 in English) measures seasonal heating efficiency. In a rural Montérégie building where heating accounts for by far the majority of the system's annual energy use, half a point of CPSC2 has a greater impact on the bill than half a point of TRÉS2. Choosing the five-ton unit here therefore did not mean “going bigger”: it meant choosing the unit whose efficiency curve matches the building's actual use.

The modulating range confirms it: from 35,000 to 60,000 BTU/h in heating. The variable-speed compressor slows down enough to avoid short cycling during the shoulder seasons while retaining the capacity needed in January.

The installation: an elevated base, not a ground-level slab

The unit rests on a galvanized steel base with adjustable feet, itself supported by concrete pads. This is not an aesthetic choice.

Why elevate the unit in a backyard

• Defrost water must be able to drain away. In winter, every defrost cycle discharges water beneath the unit. Installed directly on the ground, it refreezes and builds an ice base that eventually reaches the bottom of the coil.
• Snow accumulates at the foot of walls. A courtyard enclosed by a block wall becomes a snow trap: windblown snow settles and accumulates there well beyond the average height of unobstructed ground.
• Runoff from the wall is visible in the photo. These dark streaks on the blocks indicate decades of water running down the masonry. A unit installed at the foot of this wall receives this water continuously.

Leveling and supporting the feet

Adjustable feet are not for making up for approximate grading: they are for getting the unit level, which determines oil return to the compressor and proper drainage from the base pan. We check the level on the chassis in both axes, and check it again after setting the unit in place—because 110 kg placed on a base always settles it a little.

The other rule: the pads must rest on stable ground, not topsoil. A foot that sinks two inches during the first thaw throws the whole assembly out of alignment, puts the piping under stress, and strains the fittings.

Clearances: the most common problem and the least expensive to correct

An outdoor unit needs to draw air through its sides and rear and discharge it through the front. Anything obstructing either airflow immediately reduces efficiency.

What we addressed at this job, and what we explained to the customer before leaving:

1. Wooden pallets. Leaning against the unit, they block the air intake. They were moved, and we agreed on a clearance area to maintain permanently.
2. Vegetation. Grass, perennials, and young maple shoots that return every summer eventually end up in the coil fins. Spring maintenance takes care of the issue.
3. The angle formed by two walls. In an enclosed corner, hot air discharged in summer can be immediately drawn back in. This short-circuit raises discharge pressure, reduces capacity, and shortens the compressor’s life. The placement was chosen to let the discharge air escape toward the open yard.
4. The container. A movable bin placed in front of the air outlet on a scorching day cancels out part of the investment. It seems obvious on paper; yet we see it every summer, on the island of Montreal as well as in the surrounding regions.

We always leave the customer with a physical marker or written instructions about clearances. A properly installed unit that is buried under stored items six months later is no longer properly installed.

The long refrigerant line and the line-set cover

The outdoor unit could not be placed near the entry point, so the refrigerant line runs several meters along the concrete-block wall before reaching the mechanical room. It is protected by a white line-set cover (raceway), visible along the entire length of the wall.

What the line cover really addresses

The primary purpose of the line-set cover is not cosmetic. It protects the piping insulation from ultraviolet rays, which crack the elastomer within a few seasons and turn an insulated line into one that sweats and loses capacity. In a service yard, it also protects against mechanical impacts: carts, pallets, snowblowers, and shovels.

What length requires

On the FLEXX, the factory charge covers 24.6 ft (7.5 m). Beyond that, refrigerant must be added at a rate of 0.22 oz per foot (20 g/m) for the 48,000 and 54,000 BTU/h configurations—a different value from the 0.32 oz/ft (30 g/m) used for the smaller models, which regularly catches people who apply a single figure across the entire range.

The route was measured with a tape before evacuation, the additional charge was weighed on an electronic scale, and the value was entered on the commissioning sheet as well as on a label affixed near the service connection. The day a technician has to diagnose this system eight years from now, this label will save two hours.

The limits that must not be exceeded remain the same: 98.4 ft (30 m) of total length and 49.2 ft (15 m) of elevation difference between the two units. We add our own best-practice rules: continuous slope, no undrained low points, supports at regular intervals to prevent the line set cover from sagging, and sealed penetration fittings.

Commissioning in July: what can and cannot be checked

The work was completed in the rain, in the middle of the cooling season. This is a situation that must be described honestly to the customer.

What we fully validate in summer:

• subcooling and superheat, measured and compared with the manufacturer's target values;
• the delta T between return air and supply air;
• the system's external static pressure, with the motor running at nominal speed;
• the actual amperage of the compressor and fans, compared with the MCA;
• tightness, through evacuation below 500 microns with a rise test before opening the valves;
• the operation of the indoor unit's A2L detection sensor.

What we cannot validate in July, and what we schedule:

• actual heating performance at low temperatures;
• observing a complete defrost cycle;
• the auxiliary heat lockout and the balance point, which can only be properly adjusted once the cold season has begun.

We therefore plan a commissioning adjustment visit in the fall. A contractor who declares a heat pump “commissioned” in July without returning before winter has delivered only half the job.

Electrical connection and R32

The disconnect switch is mounted on the wall, within sight of the equipment, with a watertight flexible cable running to the terminal block. The outdoor unit requires an MCA of 39.9 A and an MOCP of 45 A; the indoor unit requires its own circuit.

The R32 is classified as a refrigerant A2L, slightly flammable, with a global warming potential significantly lower than that of R-410A. Outdoors, dilution occurs naturally; attention shifts to the indoor section and to proper handling practices: nitrogen purging during brazing, no tools not designed for A2L, and weighing the charge rather than estimating it.

What we take away from Saint-Aimé

Mistakes to avoid

• Choosing equipment based solely on its SEER2. In rural Montérégie, the CPSC2 tells the story that matters.
• Installing the outdoor unit at the base of a wall that sheds water. Water always finds a way.
• Placing an adjustable base on loose soil. The first thaw will throw everything out of alignment.
• Allowing storage to accumulate around the unit. Pallets, bins, firewood: each one reduces performance.
• Hiding a refrigerant line without documenting its length or the added charge. The line cover is a service to the building; the label is a service to the next technician.
• Considering summer commissioning as final. The heating settings are adjusted during the heating season.

Rebates and eligibility

The installed configuration is ENERGY STAR certified and bears AHRI number 217120762. This number, specific to the exact pairing of an indoor unit and an outdoor unit, is the reference on which government programs and local rebates are based. The criteria and amounts change from year to year and depend in particular on the heating source being replaced—a significant variable in an area where oil, propane, and wood are still used. We verify eligibility before signing, based on the AHRI number, never on the product line's commercial name.

Our coverage

We carry out these HVAC installations in Montreal, Laval, Longueuil, on the North Shore, on the South Shore, and in rural Montérégie, including Saint-Aimé, Massueville, Saint-Robert, Sainte-Victoire-de-Sorel, and the Sorel-Tracy area. Every project begins with a technical visit: load calculation, ductwork inspection, electrical verification, and assessment of the outdoor installation, taking into account the yard's actual use in both winter and summer.

If your central heat pump project involves a service yard, an alley, or a confined space, the location deserves just as much attention as the equipment choice. Our team conducts an on-site assessment.