Frequent mistakes we see all too often in Montreal
At AirGreen, we intervene every week to fix wall-mounted air conditioner installations that were done incorrectly—often without permits, with no respect for safety standards, or by uncertified installers. These mistakes, which are entirely avoidable, can compromise energy efficiency, shorten the lifespan of the unit, and pose serious risks to the safety of the occupants.
In this article, we’ll go over the most common errors we’ve encountered on the ground with clandestine wall-mounted air conditioner installations in Montreal, highlighting the consequences for homeowners and the benefits of hiring certified professionals like AirGreen.
The dangers of installing without a permit in Montreal
Montreal is one of the cities in Quebec with strict municipal regulations for HVAC (Heating, Ventilation and Air Conditioning) work. Any wall-mounted air conditioner installation that involves structural, electrical, or plumbing modifications requires a permit. Yet, many property owners bypass these obligations, thinking they’ll save time or money.
Consequences of installing without a permit:
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Insurance companies may refuse to cover damages.
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Heavy municipal fines.
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The installation may need to be demolished and redone to code.
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Ineligibility for government or Hydro-Québec grants.
Poor sizing of the wall-mounted air conditioner
One of the most common technical issues we encounter in the Montreal area is the selection of a wall-mounted air conditioner that’s not properly sized for the space it’s meant to cool. Many clandestine installations use 12,000 BTU units without performing a proper heat load calculation.
Problems caused by improper sizing:
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Overheating or inefficient cooling of rooms.
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Short cycling that wears out the compressor prematurely.
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Excessive electricity consumption.
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Constant discomfort for occupants.
Poor positioning of the indoor unit
A common installation mistake is mounting the wall unit too close to the ceiling or tucked into a corner, which blocks proper airflow.
The risks:
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Inadequate airflow.
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Performance loss.
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Mold growth around the unit due to poor moisture evacuation.
At AirGreen, we always assess room layout and airflow before installing a wall-mounted air conditioner, whether in Montreal, Laval, Longueuil, on the North Shore or the South Shore.
Lack of slope in drainage piping
Another mistake we frequently fix is an incorrectly installed drainage pipe, often laid flat without a downward slope, causing water to back up inside the wall or the indoor unit.
Consequences:
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Water infiltration.
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Structural damage to the building.
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Mold and unpleasant odors.
Non-compliant electrical connections
The use of extension cords, unprotected connections, or plugging into non-dedicated circuits is widespread in under-the-table installations. These practices represent a high fire risk, especially during peak energy consumption periods.
What we do:
Our certified technicians always ensure that each wall-mounted air conditioner is connected to a dedicated breaker, with wiring that complies with Quebec’s Electrical Code.
No insulation on refrigerant lines
Refrigerant lines left exposed without proper insulation are common in DIY installations. This leads to:
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Loss of energy efficiency.
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Condensation on the pipes.
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Increased electricity usage.
Use of questionable-quality equipment
Some illegal installs use wall-mounted air conditioners from unknown brands or imports without CSA certification. Not only are these units less reliable than a Fujitsu, Gree, or Tosot, but they’re also ineligible for financial assistance programs like LogisVert.
At AirGreen, we only install certified, trusted brands such as:
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Fujitsu KZCA – superior energy efficiency.
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Gree Lomo and Extreme – robust and high-performing.
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Tosot Apex – excellent value for money.
Grants denied due to uncertified installation
One often irreversible mistake: installing a wall-mounted air conditioner by an unaccredited installer automatically disqualifies you from subsidies under Hydro-Québec’s LogisVert program (up to $1,860 in grants for certain units).
At AirGreen, we always ensure that every installation meets the eligibility criteria to maximize available subsidies.
The AirGreen approach: professional, compliant, and transparent
We recently corrected an illegal installation in Rosemont where an 18,000 BTU wall-mounted air conditioner was poorly positioned and connected using an extension cord. The homeowner complained of noise, leaks, and increased electricity bills. We:
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Submitted a retroactive permit request.
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Replaced the AC unit with a certified Gree Lomo model.
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Redid the electrical connections to code.
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Reinstalled the system with proper drainage slope and insulation.
Result: a high-performance, safe, code-compliant system, eligible for a $1,704 grant, and a relieved customer.
Why choose AirGreen
We’re a local company specializing in wall-mounted air conditioner installations in Montreal, Laval, Longueuil, the North Shore and South Shore. Every project is carried out with precision, code compliance, and attention to detail.
Our guarantees:
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RBQ-certified installers.
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Personalized after-sales service.
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High-end equipment.
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Expertise to maximize grants.
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No under-the-table installations.
Tips for homeowners: how to avoid installation mistakes
Before installing a wall-mounted air conditioner, make sure:
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You’ve obtained the necessary permits.
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You’ve hired a certified company like AirGreen.
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The unit is properly sized for your space.
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The installation meets electrical and mechanical code.
Conclusion: a legal installation is a smart investment
By choosing AirGreen, you’re ensuring a safe, long-lasting, high-performance HVAC installation that complies with regulations. Avoid clandestine installs—they’ll cost you more in the long run and compromise your comfort.
We’re here to guide you, install, and maintain your system the right way, throughout Montreal and surrounding areas.