The opening left in the wall when the old appliance is removed
In the photo of this job, the eye first goes to the outdoor unit: a white cabinet suspended high on a red brick wall, steel brackets, a ladder leaning beside it, and an open window above with someone inside. That is not where the most instructive detail is found.
It is just below the new appliance: a dark grille recessed into the brick, rectangular and clearly older. An old wall penetration. A through-wall air conditioner, a fan, an air intake—something occupied this hole, and that something is no longer there.
Every HVAC installation during a renovation creates this kind of orphan, and it appears on almost no quote. It is a gap we want to address here because at Sainte-Brigide-d'Iberville, it concerns many people: according to the urban plan adopted by the municipality in November 2025, 180 of the 565 dwellings date from before 1960, and approximately 54% of the housing stock predates 1980. Homes that have had time to accumulate generations of appliances, and therefore generations of holes.
What an old wall penetration does to an abandoned wall
A penetration hole is never neutral. Left as is, it simultaneously becomes:
- an air pathway, which short-circuits the insulation exactly where the new appliance is trying to condition the room;
- a water pathway, because a grille designed for an appliance that is no longer there no longer has the air discharge that kept it dry;
- a pathway for wildlife—squirrels, birds, wasps, mice. A temperate cavity with a ready-made entrance will not stay unused for long;
- an interruption in a wall that must continue to drain.
This last point is the most misunderstood. A brick wall is not a watertight barrier: it is a rain screen, with an air cavity behind it, ties, a base flashing, and weep holes that drain the water that has passed through it. We have published the complete mechanics on our Kahnawà:ke page, and we will not repeat them here. What matters here: filling an opening without respecting this system creates a dam inside the wall, and the water emerges elsewhere—often one floor lower, often years later.
The question to ask before filling it: “Am I reusing this hole?”
The impulse is tempting. The hole exists, it is at the right height, and it avoids drilling.
On an interior drywall partition, our basic rule is indeed same location, same holes, same panel—we established it in Sorel-Tracy. On a masonry façade, it is almost always the opposite, as demonstrated by Saint-Liboire: an old penetration in brick is not an available fastening point; it is a fired crust that has already been pierced. What is filled in on brickwork is repointed; it is not reused as an anchor.
In practical terms, on a project like this, we distinguish three cases:
- The penetration is still needed for the new refrigerant-line route. It is then resized, its slope is adjusted toward the outside, and its watertightness is completely redone—not patched around what remains.
- The penetration is no longer needed and is sealed. This is masonry work, not HVAC work. We report it in writing, with a photo, and leave it to someone who does this trade.
- The penetration conceals something else. A sleeve from a removed unit, a dead duct, an old connection. No one knows before opening it.
And one thing we never do: AirGreen does not diagnose façades. We observe, photograph, and document. The condition of the joints, the weep-hole line, and the presence of efflorescence or spalling within the first metre are observations we pass along, not verdicts we issue.
The corollary no one likes to hear
A suspended cabinet occupies this section of wall for the entire life of the equipment. A mason does not work behind an installed cabinet. If the brickwork in this section needs repointing in the coming years, the order of work is reversed: masonry first, equipment afterward. Installing on a wall that needs work means paying twice—once for the installation, and once for removal and reinstallation.
This is why the age of the masonry is a quotation question, not a site discovery. In a village core where, by the planning document’s own admission, “several buildings dating from the nineteenth century are very well maintained,” the question is anything but theoretical.
What we record in the final project file
- The exact number of anchors, their positions, and the brick course in which they land.
- Existing penetrations observed, whether reused or not, along with their condition.
- The clearances and their rationale — “60 cm at the back because that is where it draws air.”
- A dated photo of the installation, which becomes the reference evidence if the unit ever shifts on its supports.
This file does not exist for us. It exists for the next technician, and for the next buyer of the house.
A job taking place on both sides of the wall at the same time
Look at the photo again. The ladder is outside. The window is open. Someone is inside. And a plastic tray is placed on the windowsill.
This is the physical reality of installing a wall-mounted heat pump that sales articles never show: at several points during the day, the work takes place simultaneously in two locations separated by a wall, with two people who cannot see each other.
Why this changes the price, and why it is legitimate
A unit installed on the ground, against a wall, at chest height is installed differently from a unit suspended overhead on a brick façade. The difference is not an arbitrary surcharge:
- Access determines the number of people. A load carried at height cannot be handled alone. The ladder’s ground footprint determines where it can be placed — the Southwest rule.
- Mounting height is determined by the service valves, not aesthetics: that is where the unit will be handled for fifteen years. Villeray established this, and Saint-Lazare draws the commercial conclusion: a unit that cannot be serviced is, in practice, a unit without warranty.
- Future maintenance inherits today's decision. Every annual cleaning and every service call will be carried out with the same ladder, under the same conditions.
A contractor who gives the same price for a ground-level installation and an elevated installation has not looked at the wall.
What the homeowner needs to prepare, and no one tells them
The list we send before installation day:
- Clear the room where the indoor head will go — furniture, rugs, curtains, and pictures from the wall concerned. Cleaning and commissioning are occasionally wet operations: the floor and approximately one metre in front must be able to get wet without consequence.
- Clear the outdoor passage to the base of the wall, including anything habitually stored there.
- Identify an available electrical outlet nearby and a water source.
- Plan for movement, because there will be trips back and forth between the inside and outside, often through the same door.
- On a multi-head system, plan room by room, not unit by unit.
And a safety instruction that is not a formality: while a ladder is leaning against the wall, no one else is allowed in the area at the foot of that ladder. No children, animals, or cars backing up.
What the window-sill pan reminds us
A container beneath a work area is a momentary cleanliness measure. It should never become a permanent fixture. A pan left under a unit fills with defrost water, freezes, and turns into a column of ice instead of preventing it. Drainage is managed with a slope and a clear path, not a container.
The equipment: why the smallest cabinet is often the right cabinet for elevated mounting
When mounting is done up high, on masonry, weight is no longer a detail. A suspended cabinet is subject to four cumulative loads — its own weight, vibration as a fatigue load over millions of cycles, ice and snow pulling on the exposed drop, and wind trying to rotate it around its supports. We published this mechanics analysis in Saint-Louis, and we are adding no figures: an HVAC contractor who improvises a structural calculation is working outside their trade.
What we can say is that the GREE FreeMatch GWHD(18)ND6MO weighs 35.5 kg, compared with 78.5 kg for the GWHD(36) and 79 kg for the GWHD(42). That is less than half. On a brick wall at floor height, that difference is not cosmetic.
Two 9,000 BTU/h wall-mounted heads, for a total of 18,000 BTU/h—exactly 100% of the rated capacity. We openly note that this combination has already been published in this series: it is the suitable configuration, not a new one.
| Feature | GWHD(18)ND6MO |
|---|---|
| Rated capacity | 18,000 BTU/h in both cooling and heating |
| Modulation range (heating) | 7,300–18,100 BTU/h |
| Efficiency ratings | SEER2 21 · HSPF2 10 · EER2 12.5 · EER 3.52 · COP 3.9 |
| Operating range | −30 °C to 48 °C in cooling mode, −30 °C to 24 °C in heating mode |
| Refrigerant | R-32 (A2L), 900 g, integrated leak detector |
| Electrical | 208/230 V · MCA 14.5 A · MOCP 20 A |
| Dimensions / weight | 822 × 550 × 352 mm · 35.5 kg |
| Airflow | 1,354 ft³/min |
| AHRI codes | 214931586 / 214931591 / 214931592 |
A model-specific pitfall you need to know before signing: its factory charge covers 10 metres of piping, the shortest in the entire range—the GWHD(24) covers 30, while the GWHD(30) and GWHD(36) cover 40. Its maximum total allowable length is 40 m, with a maximum elevation difference of 15 m. Yet a unit suspended at floor height requires a vertical run before the horizontal run even begins. Ten metres can be used up quickly. Beyond that, refrigerant must be added—20 g per additional metre, weighed and recorded, never estimated. A quote that does not mention the actual developed length cannot be compared with another.
Permits and regulations: what Sainte-Brigide-d'Iberville says, and what we are not claiming
The municipality completely replaced its planning by-laws in November 2025. Any earlier information is outdated—including information that is still circulating online.
What we verified:
- The 2025-477 by-law (permits and certificates) includes, under the heading Accessory Equipment, a fee item: “Heat pump and other equipment of the same nature — $20”. A fee exists, so an authorization exists.
- By-law 2025-479 (SIP), applicable to the village core, states in article 4.3.2 mm): “Mechanical equipment (air conditioning, ventilation) must be integrated into the building so that it is not visible from the roadway.” For a house on Principale Street, this is the constraint that determines the facade, before any technical consideration.
- Zoning By-law 2025-474 contains three dedicated articles — 6.13, 6.35 and 6.69 — expressly concerning heat pumps and heat-exchange equipment. We were unable to read the text: the document is truncated during consultation before the relevant pages.
We therefore will publish no setback in meters, no screening requirement, and no maximum height. A figure of three meters for this municipality is circulating online, without a bylaw or article number: we do not repeat it. A 3 m distance would be unusually large for a rural municipality, and above all, it is not backed by any verifiable source.
The reliable contact is straightforward: Antoine Gauthier, building inspector, 450 293-7511 extension 3. A practical detail worth its weight in gold — he is available on Wednesdays only, and the town hall is closed on Mondays. A project planned without taking this window into account loses a week.
Sainte-Brigide-d'Iberville, a few verified facts
The name tells two stories at once: Saint Brigid of Kildare, the patron saint chosen in 1846 in honor of the Irish settlers established there, and Iberville, added in 1891 after the county, for Pierre Le Moyne d'Iberville. An Irish saint and a French naval officer in the same place name.
Nearly 99% of the territory is in a permanent agricultural zone — 53 farms, with Class 2 and 3 soils. The Saint-Brigide Church, built in 1863–1864 by Victor Bourgeau, one of the great church architects of 19th-century Quebec, stands at 500 Principale Street; it is listed in Quebec's Cultural Heritage Directory, which is neither “classified” nor “cited.” And the Western Competition Festival, active since the late 1990s, brings together between 1,200 and 1,500 horses there every summer.
A geographical detail few people mention: despite belonging to the Haut-Richelieu RCM, the municipality is crossed by the Southwest River, a tributary of the Yamaska—it does not drain toward the Richelieu. The urban plan nevertheless identifies several floodplains and erosion zones along this river: a ground-level installation must be assessed on a case-by-case basis.
With 86.7% of homes being detached single-family houses, 83.3% of residents being homeowners, and a housing stock largely dating from before 1980, this is territory made for the wall-mounted heat pump: homes without ductwork, where adding comfort means installing wall-mounted heads rather than a central system.
Mistakes to avoid
- Leave an old penetration open or seal it without respecting the wall's drainage.
- Reuse a masonry hole as an anchoring point.
- Install it on a section of brick that will need repointing.
- Compare two quotes without the actual developed length, especially for a GWHD(18) and its 10 m precharge.
- Leave a bin under the unit after the crew leaves.
- Plan without taking into account the inspector's Wednesday, or the PIIA if the house faces Main Street.
Rebates and support
These units are eligible for local rebates, and the AHRI codes above are required by the programs. We support every application for LogisVert, Rénoclimat and Chauffez vert, recording the codes in the project-completion file. We do not promise any amount: the amounts are set by the programs and may change.
Why AirGreen
At AirGreen, we look at the wall before looking at the catalog. We read the regulations rather than summarizing them from memory, we quote without interpreting, we call the inspector when the text is unreadable, and we refuse to publish a figure we cannot substantiate. Our teams cover Montreal, Laval, Longueuil, the North Shore and the South Shore, including the agricultural municipalities of Haut-Richelieu.
For an assessment in Sainte-Brigide-d'Iberville, write to us: we measure and verify before making a proposal.