Installation of a GREE FREEMATCH R32 two-head heat pump in Lorraine, in the Laurentians region

A condenser on a white membrane, in the full late-afternoon sun

This page is the first in our FreeMatch R32 series devoted to Lorraine. After documenting around sixty projects on the Island of Montreal, in Montérégie, Laval, and Bois-des-Filion, we are arriving in a city that has almost nothing in common with the previous ones: six square kilometers, approximately ten thousand residents, almost exclusively detached single-family homes, no sidewalks, no apartment buildings, no traffic lights—and above all, no overhead wires. All utilities are buried. This feature, decided upon when the city was founded in 1960, still determines how an HVAC project is approached in this area today. That is the subject of the second half of this article.

The unit is a GREE FREEMATCH R32 GWHD(42)ND6MO, with two wall-mounted heads, and the condenser rests on an aluminum four-leg support set on wooden sleepers, above a light-colored roofing membrane. The bundle of conduits, wrapped in white spiral tape, heads to the right and then descends. The photo was taken at the very end of a summer day, with the low sun aligned with the lens—and that light is precisely the starting point for the first half of the article.

We have had the debate about the model elsewhere eight times, and we are not doing it again. The third port and the heating reserve: Beaconsfield. The “min. – max.” line rather than the “nominal” line: Dorval. A single head must never equal the entire compressor: Kirkland. The run length that determines the unit: Dollard-des-Ormeaux. The precharge that costs money versus the maximum length that is non-negotiable: Côte-des-Neiges–Notre-Dame-de-Grâce. The performance of the 30k: Pierrefonds-Roxboro. The shared cabinet for the three larger models: Villeray. The fifth port purchased to avoid a second permit: Westmount.

The house, the two zones, and what we do not promise

Only two zones: the open main-floor area and one enclosed room upstairs. No ductwork in the house; electric baseboard heating retained throughout. One 24,000 BTU/h head in the large space and one 12,000 BTU/h head in the enclosed room, for 36,000 BTU/h of installed indoor capacity. The baseboards remain in service, set 2 to 3°C below the heads' setpoints—the mechanism is explained on our Saint-Amable page.

Written plainly in the handover file: the basement is not served, the upstairs bedrooms are not served either, and a closed door cancels the effect in the room behind it. Two heads serve two zones, not a house.

The model choice, in three hundred words

AHRI certification 214931590 (non-ducted), 214931596 (ducted), 214931600 (mixed), depending on the declared combination. Developed runs of 13 m and 19 m, totaling 32 m, well within the GWHD(42)'s 50 m precharge: no R32 was added, and the minimum-area calculation related to the A2L refrigerant remains based on the documented factory charge of 2,700 g. Approximately 5 m of elevation difference versus 25 m permitted.

Only two reasons, and neither is new: the 42k is more efficient than the 36k in this range—EER 3.81 and COP 3.9 versus 3.52 and 3.56—a reading published on our Rivière-des-Prairies–Pointe-aux-Trembles page; and a rooftop run is structurally longer than a ground-level run, as our Dollard-des-Ormeaux page established. The 50 m precharge versus 40 m on the 36k therefore has real value here.

Three power ratings in the same table, and none is used for electrical calculations

This is the only new reading we retain from the data sheet for this page. The GWHD(42) table prints three values in watts, and they do not mean the same thing. 3,230 W in cooling and 3,150 W in heating are the system's consumption under standardized test conditions: they are used to estimate a bill, not to size a circuit. 3,514 W is the power input of the compressor alone, at its own maximum—a figure higher than the other two, which is confusing when read quickly, and which describes a component rather than an appliance.

What matters to the master electrician are the amps: MCA 30 A, which sets the minimum conductor size, and MOCP 45 A, which sets the value the protective device must not exceed. This distinction is published on our Rosemont–La Petite-Patrie page, and we will not repeat it. What we add here: none of the three wattage ratings enters into this calculation, and a quote that justifies a breaker rating by citing watts has not read the right line.

The honest price of this configuration: 79 kg, the heaviest in the range, to be lifted onto a roof and lowered again when the membrane is replaced—the lifting logistics are itemized on our Rivière-des-Prairies–Pointe-aux-Trembles page. 63 dB(A), the highest in the range. And a MOCP of 45 A in a residential panel that does not always have the space.

The unit does not breathe the weather-bulletin air

A condenser rejects heat into the air it draws in. Its stated capacity is measured at an air temperature, not at a location. Our Mercier–Hochelaga-Maisonneuve page explained this principle for a paved urban courtyard; here is its rooftop version, which is not the same and is less well known.

On a flat roof, two things warm the air the unit draws in. The roofing surface itself, which heats up in the sun and warms the thin layer of air above it—exactly where the intake faces of a unit mounted low on sleepers are located. And direct radiation onto the cabinet, which does not affect the cycle’s thermodynamics but does heat the sheet metal, oil, electrical compartment, and everything inside it.

Let us be honest right away: we do not publish any temperature difference in degrees. The X610068B specification sheet contains no capacity data for high outdoor temperatures—the absence is documented on our Mercier–Hochelaga-Maisonneuve page, and it applies here as well. The effect is real, it is second-order, and it does not change the model selection. It changes two concrete things: the unit’s orientation, and what we refuse to build around it.

The white membrane paradox

The clear membrane visible on this site is unequivocally a good thing for the building: less heat transferred to the floor beneath the roof, and therefore less load on the system we have just installed. We would never recommend replacing it with a dark membrane to ease the condenser’s burden.

But radiation reflected by a surface has to go somewhere, and some of it goes into whatever is standing on that surface. A condenser on a light-colored membrane is immersed in a field of reflected light that it would not have at ground level, where grass, stone, and the shade of a wall absorb rather than reflect. This is one reason why the same, correctly sized unit does not behave identically in a shaded side yard and on a fully exposed roof — and it is a reason to think about placement, never a reason to forgo a reflective membrane.

The fan face does not decide

A condenser draws air in through the back and sides and discharges it through the front: the demonstration is provided on our Pierrefonds-Roxboro page, along with the consequence for rinsing. Orientation is therefore determined by the intake faces, not by the face we see.

Three rules applied here:

1. The intake faces must have open sky above them, not a hot parapet or a southwest-facing brick wall that gives back its energy in the late afternoon.
2. The discharge axis must point toward the clearance, never into an inside corner — recirculation and its thermal cost are covered on our Ahuntsic-Cartierville page, and there is no error code that says “the unit is rebreathing.”
3. Clearance must be measured with whatever will later be added to the roof in mind, because a roof changes after we leave: our Pointe-Claire page covers the mechanical neighbors of a rooftop condenser—vents, hoods, chimneys, and guy wires.

You do not shade a condenser

That is the trap, and the most useful rule in this section. Knowing that the sun has a cost, the instinct is to build a shelter. An awning, a panel, a sheet of plywood on legs.

The gain is second-order; the loss, however, is first-order. Our Les Cèdres page lists the three ways to build a condenser shelter incorrectly — too low, enclosed sides, resting on the unit — and each costs more than the radiation it blocks. Our Westmount page describes the same mechanism as a visual screen that turns the unit into a self-rebreathing enclosure. Vegetation shade is a real benefit for air conditioning, but it comes with its nuisances — samaras, resin, falling branches — detailed on our Rigaud page; and on a roof there is no hedge or tree to call upon anyway.

The answer on a roof is therefore not to provide shade. It is to orient and clear. And never, in any season, to cover the unit: the winter cover is discussed on our Ahuntsic-Cartierville page.

What the sun does to everything surrounding the unit

The unit is designed to live outdoors. What surrounds it is less so, and on a light-colored roof these components receive more radiation for longer, without a single hour of shade during the day:

• Duct insulation. Ultraviolet degradation and the need for a continuous protective jacket along the entire exterior run are established on our Dollard-des-Ormeaux page. On a reflective membrane, the underside of the bundle is exposed to it as well.
• Anti-vibration pads, which harden and compress over time, and wood sleepers, which are not eternal: both points are published on our Pierrefonds-Roxboro page, along with the reminder that a unit that is no longer level stops draining water from its pan properly.
• Plastic fasteners and clamps, which turn white and snap after a few summers, often before anyone thinks to inspect them.

None of these issues triggers an alarm. All are checked during the annual inspection, the contents of which are published on our Pierrefonds-Roxboro page.

The last hour of daylight, and the point of no return

Here is the point this photo makes obvious and that the series had never addressed: a roof has no lighting.

The installation sequence for a mini-split ends with opening the service valves, and our Côte Saint-Luc page named it for what it is: the point of no return, since correcting an issue after this step requires recovering the charge. Before that come the flares, the nitrogen test, the deep vacuum and the micron-gauge rise test, followed by the weighed top-up.

Each of these steps requires you to see: see a flare, see a pressure gauge, see a display, see a soap bubble on a fitting. At seven p.m. in August on a white membrane, you can still see very well. Forty minutes later, you can see nothing, and using a phone held between your teeth for lighting is not a method.

Our job-site rule, published here for the first time:

• Roofing work starts early, and the day's schedule is built backward from sunset, not from the arrival time.
• If the day goes off track, the valves remain closed. The circuit stays under nitrogen or vacuum, clean and documented, and commissioning is completed the next morning. Leaving a unit unopened overnight costs no one anything; rushed commissioning by headlamp costs for fifteen years.
• Nameplate and serial-number photos should be taken while it is still light, not when it is time to pack up. The equipment identification and its documentation are covered on our Villeray page.
• Coming down from the roof should be done while there is still daylight. This is not a matter of comfort.

A contractor who offers to “finish this tonight” on a roof is doing so to avoid coming back. That is understandable, but it is not in your best interest.

What lies beneath a Lorraine property, and why no one sees it

A city without poles

Lorraine was founded on February 4, 1960, on the Garth estate, as part of a federal new-town program, and its name comes from the French region. It was designed all at once, with choices that still endure: detached houses almost everywhere, no sidewalks, no apartment buildings, no traffic lights, a significant portion of the territory left as forest—the Grand Coteau forest—and entirely underground utility networks, except in the oldest areas. In other words: no poles, no overhead wires. Approximately 9,500 residents according to the 2021 census, spread across nearly 6 km² and divided in two by Highway 640.

For an HVAC contractor, this is not a matter of aesthetics. It is a jobsite consideration, and it has two opposing consequences.

The first consequence: the wall is more open

In Ville-Marie, we published an entire chapter on the condenser and the overhead electrical service entrance—the workspace in front of the meter, the mast that supports nothing but itself, and the defrost plume that must never be directed toward a meter base. In Lorraine, this constraint largely disappears: there is neither a service mast nor a masthead on the façade, since the service enters from below.

The meter itself remains on the wall. The clearances concerning it still apply; they fall under the distributor and the master electrician, and our internal twenty-four-inch standard is published on our Montréal-Est page. But the wall geometry is simpler than elsewhere, and that is a rare piece of good news.

The second consequence: the ground is no longer clear at all

Everything that is not in the air is underground. On a property in Lorraine, beneath the lawn, there may be the building's electrical service, telecommunications, cable lines, water, sewer, and, depending on the area, other utilities as well.

And a heat pump project affects the ground more often than you might think: a concrete base, screw piles—the three basic types are compared on our Rigaud page—, a trench for running a bundle to a remote unit, as detailed on our Côte-des-Neiges–Notre-Dame-de-Grâce page with its conduit and continuous insulation, or simply a stake, anchor, or screen-fence post.

The locate request, and who must submit it

In Quebec, underground infrastructure locating is handled through Info-Excavation, an organization that coordinates requests with its members. The request is free. It is intended both for property owners who want to install a fence, landscape their property, or dig for a pool and for excavation contractors or municipalities, and it covers telecommunications, water and sewer services, electricity, and natural gas, among others. There is a delay between the request and marking: it must be scheduled, not made up for later.

Our policy, stated in the quote, is clear: we do not screw in a pile, drive a stake, or open a trench on a property whose utilities have not been located. If the schedule does not allow time for locating, the installation plan changes—it is not guessed.

What the locate does not cover—and no one tells you

This is the most important point in this section, and it comes directly from the organization itself: not all owners of underground infrastructure are members of Info-Excavation. It is therefore up to the requester to contact the relevant organizations directly regarding anything not covered.

To that, add everything that, by definition, will never appear in a public locate because it is private and often undocumented: the power cable to a shed, landscape lighting wiring, the line to an in-ground pool, a French drain, a generator, or a charging station installed later. On a well-maintained residential property, these private lines are common, and no one has a plan showing them.

Our method: during the technical visit, the homeowner is asked about what they personally had buried since moving into the house—and the answer is recorded in the file. This directly extends what our Saint-Télesphore page publishes for private services in rural areas, where the line between the well and the house is located before digging and where the septic field receives neither a base, nor a post, nor a trench, nor machinery traffic.

One useful reminder to finish: cutting a low-voltage cable does not trip any circuit breaker. The device simply stops working, often weeks later, and no one connects it to the work—the mechanism is described on our Côte Saint-Luc page for surface wiring, and it is even more applicable underground.

Roof or ground: how the question was settled here

Ground installation requires a base, which means a location, which means a delay, and a landscaped property to cross. Roof installation requires lifting, a support distributed over sleepers, and service access designed for winter. Neither option is free; they are two different bundles of constraints, and the choice is made with the client, with the figures in hand, before ordering.

Here, the roof won out. Everything concerning roof assembly has already been published and we do not repeat it: the membrane that is never punctured, the sleepers that distribute the load, the roofer’s warranty, the parapet penetration, and the membrane’s age as a bid question are covered on our Dollard-des-Ormeaux page; the roof’s mechanical neighbors, on the Pointe-Claire page; the support’s galvanic corrosion, plumbness, and cushion aging, on the Pierrefonds-Roxboro page; the separately itemized lifting, on the Rivière-des-Prairies–Pointe-aux-Trembles page; and the written authorization that must name the roof, on the Plateau-Mont-Royal page.

Mistakes to avoid

• Build a shelter or screen to shade a condenser: the thermal gain is marginal, but the loss of airflow is not.
• Cover the unit for the winter.
• Determine the orientation based on the fan face rather than the intake faces.
• Open the service valves and “complete commissioning” after dark on a roof.
• Leaving nameplate and serial-number photos until the end of the day.
• Digging, drilling, or screwing into anything on a property whose utility lines have not been located.
• Believing that one locate covers absolutely everything: private utility lines and the owner's private networks are not included.
• Justifying a breaker rating with wattage instead of the MCA and MOCP shown on the data sheet.
• Accepting a rooftop quote that says nothing about lifting requirements or the age of the membrane.

Grants and eligibility

A dual-zone ductless heat pump installed alongside electric heating does not open the same doors as a conversion from a fossil fuel. Chauffez vert does not apply to an all-electric home. LogisVert and Rénoclimat each have their own eligibility conditions, performance requirements, and supporting documents, including the AHRI code for the combination actually installed — an administrative as well as technical point, developed on our Saint-Anicet page. We verify eligibility when opening the file rather than announcing it in advance, and no amount is promised in an AirGreen quote: figures circulating on third-party sites contradict one another from page to page.

Why entrust this kind of project to AirGreen

Because we treat the roof and the ground as structures, not surfaces. We install HVAC systems in Montreal, Laval, Longueuil, on the North Shore — Lorraine, Rosemère, Bois-des-Filion, Blainville, Sainte-Thérèse, Boisbriand, Terrebonne — and on the South Shore. We document every HVAC installation: models, serial number for each component, developed line lengths, weighed-in charge, and commissioning readings. We do not confirm a commissioning that daylight did not allow us to perform properly, and we do not put anything in the ground before the ground has been properly surveyed. Our RBQ licence 5645-9605-01 can be verified online, just like that of any contractor you ask for a quote.

For a two-head heat pump, a multi-zone project, a rooftop installation, or an HVAC maintenance contract in Lorraine or elsewhere in the Lower Laurentians, write to us at sales@airgreen.ca or call (514) 316-2973. We will tell you what the unit will do, what it will not do, and what we refuse to do in the dark.