A narrow hallway, a cathedral ceiling, and a -30 °C winter: the assignment we received in Sherrington
Some projects can be resolved by looking at a plan. This one was resolved by climbing a staircase, looking up at a sloped ceiling, and realizing that exactly one usable wall remained throughout the entire rear section of the house. This is the kind of constraint that distinguishes a proper HVAC installation from one that actually works fifteen years later.
The context: a black-earth home undergoing renovation
Saint-Patrice-de-Sherrington is unlike the rest of the South Shore. We are in the black earth of Les Jardins-de-Napierville, a flat, open agricultural area swept by wind, where temperature swings are more pronounced than in Longueuil or Montreal. Homes there are often older, frequently expanded in successive sections, and rarely designed around a centralized air-distribution system.
Our clients were in the midst of interior renovations when they contacted us. The laundry-room shelves had been removed, the floors were protected, and painting was next. This is precisely the ideal time to integrate a wall-mounted heat pump: the refrigerant lines, condensate drain, and electrical supply can be routed before finishing, with no aesthetic compromises and no drywall repairs afterward.
The mandate was clear: heat and cool the rear portion of the house—bedrooms, bathroom, and hallway—without touching the existing system, without ductwork, and with a unit capable of holding up during January nights when the mercury drops below -25 °C.
Why the hallway rather than the living room
The chosen location often surprises homeowners. We installed the indoor unit above the laundry-room door frame, in the hallway, rather than in a main living area. This choice was based on three considerations:
- Distribution. A central corridor acts as a natural plenum. Blown air travels down the corridor, supplies the adjacent openings, and returns from below. This is the best way to cover several rooms with a single unit.
- Access to exterior walls. The selected wall provided a short, clean route outdoors without passing through a finished space that had already been renovated.
- Acoustic comfort. No bed headboard is directly beneath the airflow. In quiet mode, the unit drops to 23 dB(A)—below the sound level of an empty bedroom—but positioning it away from sleeping areas eliminates the issue entirely.
What the mounting height actually changes
The ceiling in this corridor is sloped, and the clearance above the unit was limited. A wall-mounted heat pump requires precise clearances, specified by the manufacturer, above and on each side of the cabinet: this space allows return air to enter the coil freely. Reducing this clearance to “hide” the unit higher up chokes airflow, lowers efficiency, and causes premature icing in heating mode.
We therefore positioned the mounting plate to the millimeter, taking the ceiling slope into account rather than aligning it with a visual line that merely “looks right.” The unit measures 894 mm wide, 295 mm high, and 280 mm deep and weighs 14 kg—compact, but long enough to require anchoring into solid material, not drywall alone. The plate was secured to the studs.
The appliance choice: FUJITSU Orion XLTH+ 12,000 BTU
We selected the FUJITSU AIRSTAGE Orion XLTH+, H series, in a single-zone configuration: indoor unit ASUH12KTAS and outdoor unit AOUH12KTAP1.
The numbers that matter in Montérégie
| Data | Value (12KTAP1) |
|---|---|
| Rated cooling | 12,000 BTU/h (modulation from 3,100 to 17,300) |
| Rated heating | 15,300 BTU/h (modulation from 4,500 to 27,300) |
| VERY (SEER2) | 31,5 |
| Region V CPSC (HSPF2) | 11,3 |
| Heating range | down to -30 °C |
| Refrigerant | R-32 (GWP 675) |
| Certification | ENERGY STAR, including Cold Climate |
Yet the most important line is not in this table. It is this: at -21 °C, the unit still delivers 156% of its rated capacity, and at -30 °C, it still delivers 103%. In other words, precisely when a home in Sherrington needs heat most, this heat pump produces more than its rating on the label, without any cutoff device that would shut it down in favor of baseboard heaters.
This is where the difference between a “cold-climate” unit and an ordinary one becomes apparent. Many systems sold in the Greater Montréal area stop modulating at around -15 °C or -20 °C. The homeowner does not notice in November. They notice in January, on their electricity bill.
R-32: less refrigerant, less impact
R-32 has a global warming potential of 675, compared with 2,088 for R-410A—a 68% reduction. The system also requires a smaller charge for equivalent performance. For a home in an agricultural area, another detail matters: ProCore coils made of highly corrosion-resistant copper. In an area where the air carries soil dust, fertilizer, and nitrogen compounds for much of the year, this is not just a brochure claim.
The project timeline, from drilling to commissioning
Step 1 — Routing the lines and condensate drain
Because the mounting wall is a partition wall, the refrigerant lines (3/8-inch gas, 1/4-inch liquid) were routed laterally before exiting toward the outdoor unit. The total length remained under the unit’s 14.9 m precharged length, avoiding any need to add refrigerant on site—a point few homeowners verify, even though an incorrectly calculated charge is one of the leading causes of underperformance.
The drain: the real pitfall of corridor installations
A wall-mounted indoor unit has no obvious gravity drain. We require a continuous slope from the condensate pan to the discharge point, with no reverse slope, no “belly” in the hose, and no compression of the tube behind a stud. A drain that rises two centimeters along its route will eventually overflow—sometimes three summers later, in a freshly painted wall. The route was checked with a level before the wall was closed, and the tube was insulated along the entire section passing through an unconditioned space to prevent exterior condensation on the casing.
Step 2 — The outdoor unit: wind, snow, and exposure
The outdoor unit of the 12KTAP1 weighs 42 kg and measures 716 × 820 × 315 mm. In an area as open as Sherrington, two precautions are essential:
- Raise the support well above the accumulated snow line, rather than to the standard height used in densely populated urban areas. Windblown powder snow accumulates against obstacles; the outdoor unit is one of them.
- Protect the air intake from the prevailing wind direction. FUJITSU offers accessories designed for these conditions: snow hood, wind deflector, and hail protection. We systematically assess their suitability based on the building’s actual orientation.
The unit includes a base pan heater designed for extremely cold climates, which prevents ice from accumulating in the bottom of the chassis during defrost cycles. Without this device, defrost water refreezes and eventually blocks the fan.
Step 3 — Power supply and commissioning
The dedicated circuit was protected by a 20 A circuit breaker at 208–230 V single-phase, in accordance with the manufacturer’s requirements. Commissioning followed our usual protocol: extended evacuation until a stable deep vacuum was achieved, vacuum hold verification, opening the valves, checking pressures and temperatures in heating and cooling modes, then configuring the built-in Wi-Fi and the AIRSTAGE app with the homeowners.
Evacuation is the step most often neglected in the industry. Residual moisture in the R-32 circuit degrades the oil, acidifies the system, and destroys the compressor—slowly, silently, and well after the labor warranty of the competitor who cut corners has expired.
The mistakes we most often correct in other installations
- Oversize “to be safe.” An oversized unit short-cycles, dehumidifies poorly, and wears out its compressor. The Orion XLTH+’s modulation down to 4,500 BTU/h is an asset only if the maximum capacity truly matches the building.
- Ignore closed doors. A wall-mounted heat pump in a hallway will not heat a bedroom whose door stays closed day and night. We discuss this before installation, not afterward.
- Neglecting the washable filter. It can be cleaned with warm water in just a few minutes, a few times per season. A dirty filter reduces efficiency faster than any mechanical defect.
- Choosing a unit without a valid AHRI number. Without this certified indoor/outdoor combination, no subsidy is possible.
Subsidies: what changed in 2026
Two facts to know before signing anything:
- Chauffez vert has ended. Applications had to be submitted no later than March 31, 2026. Several websites still present it as available; that is no longer the case.
- Hydro-Québec's LogisVert program remains active, but the rules have become stricter. The unit must be ENERGY STAR certified, have a valid AHRI number, appear on the list of eligible units, and be installed by a contractor enrolled in the program. The FUJITSU Orion XLTH+ meets the ENERGY STAR requirements, including Cold Climate recognition.
Amounts and terms change from one season to the next. We verify eligibility when preparing the quote rather than promise an amount that may no longer apply when the work is carried out.
AirGreen in Montérégie, on the South Shore, and elsewhere in Greater Montréal
We install wall-mounted heat pumps, central systems, multi-zone units, and air conditioning solutions in Montréal, Laval, Longueuil, on the North Shore and the South Shore, including the agricultural municipalities of Montérégie such as Sherrington, Napierville, Saint-Rémi, and Hemmingford. Our teams understand the particularities of each area: clearance constraints in densely populated urban zones, municipal noise regulations, and wind exposure in open areas.
The Saint-Patrice-de-Sherrington project was completed in a single day, before painting, with no drywall repairs and no surprises. That's the result we aim for with every HVAC installation.
For an evaluation of your project—replacement, zone addition, conversion, or new installation—contact us. We come to your home, take measurements, and explain why we recommend one unit over another.