When a well-intentioned HVAC installation turns into a headache: what we see far too often in the field
At AirGreen, we intervene every week in Montréal, Laval, Longueuil, on the North Shore and the South Shore to repair or redo poorly executed HVAC installations—sometimes even performed by professionals. These avoidable mistakes can lead to significant extra costs, reduced energy efficiency, and premature breakdowns. Here, we share the most common errors we observe when installing cassette, ducted, console, or ceiling-floor units, and how our expertise prevents them.
Incorrect sizing of the unit: a classic with costly consequences
One of the most frequent mistakes is incorrectly sizing the BTU capacity of the heat pump or wall-mounted air conditioner. An oversized system will cause short cycles, wearing out components prematurely and causing excessive humidity in the home. Conversely, an undersized unit will never deliver the expected comfort, especially during temperature extremes.
At AirGreen, we always perform a full thermal analysis before any installation. For example, in a home in Ahuntsic, Montréal, a previous contractor had installed an 18,000 BTU cassette unit for a space that required 24,000 BTU. The result: discomfort and energy waste. We fixed the issue by installing a Fujitsu RGLX 24,000 BTU model, ensuring stable comfort year-round.
Choosing an inadequate location: impact on efficiency and durability
A poor indoor unit location can block air circulation, create unpleasant noise, or generate hot/cold spots in the room. This issue often arises with ducted or ceiling-floor units that are poorly integrated into the interior layout or poorly oriented.
On a job in Laval, a contractor had installed a console unit directly under a poorly insulated window. The unit was overworking to compensate for thermal loss. After our assessment, we relocated the unit and improved the insulation, reducing energy consumption by 20% according to the client’s follow-up.
Ignoring the unit’s tilt and support
This may seem minor, but an improper installation angle for a cassette or console unit can hinder condensate drainage, leading to water leaks inside the home. This often happens with ceiling or high-mounted installations, especially with 4-way cassette units.
We recently corrected this type of problem in a duplex in Vieux-Longueuil. The Gree U-match cassette unit had not been properly leveled, causing water to overflow from the drain pan. We readjusted everything and installed an additional lift pump with a safety sensor to ensure optimal operation.
Overlooking electrical and ventilation standards: risks not to be underestimated
Many installers underestimate the importance of meeting electrical standards and ventilation rules, especially with ducted units requiring a well-balanced duct network. Inadequate wiring or an incorrectly sized breaker can lead to frequent shutoffs, or worse, put occupants at risk.
A homeowner in Brossard contacted us after experiencing multiple failures with his central heat pump Bosch BOVA 36,000 BTU. The wiring was non-compliant, and the thermostat didn’t communicate properly with the outdoor unit. Our team reconfigured everything according to the Quebec Electrical Code, ensuring reliable and safe performance.
Installing without considering available grants
Many clients miss out on valuable rebates simply because their installer didn’t inform them of eligibility criteria. At AirGreen, we incorporate from the start the requirements of programs like Hydro-Québec’s LogisVert, Rénoclimat, or even municipal incentives from Laval or Longueuil.
For example, during a project in Sainte-Thérèse, we guided a client toward a Gree Extreme 18,000 BTU model eligible for a $1,704 rebate, while their initial quote was for a non-certified unit. Not only did they get a high-performance system, but also substantial financial assistance.
Failing to plan for future maintenance access
Some installations are perfect—until it’s time for maintenance. Units installed inaccessibly, often in drop ceilings or tight spaces, make servicing complex, lengthy, and expensive. This is particularly true for ducted or ceiling-floor units.
Our team, during a project in a secondary school in Repentigny, anticipated this problem from the design phase. By creating strategically placed access panels and using front-removable filters, we facilitated quarterly maintenance and prevented unexpected service disruptions.
The advantages of working with AirGreen
At AirGreen, our reputation is built on a rigorous, transparent, and technical approach. We are certified, trained on the top-performing brands in the industry (Fujitsu, Gree, Bosch, Sharp, Mitsubishi, etc.), and we respond quickly across the Greater Montréal region.
Our methodology is based on:
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A personalized and detailed evaluation of your space.
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Selection of certified, energy-efficient units eligible for rebates.
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A careful installation process, fully compliant with electrical, thermal, and HVAC standards.
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Post-installation support to ensure long-term satisfaction.
Practical tips to avoid these errors in your project
Work with a recognized installer
Always ask for:
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Proof of RBQ certification.
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Verifiable client references.
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A free technical visit before any commitment.
Request a thermal model
A serious installer like AirGreen doesn’t just “guess” the size of a system. We carry out precise thermal load calculations, taking into account sunlight, insulation, air volume, and occupant habits.
Prioritize units compatible with rebates
We help you select certified Energy Star or Novoclimat-approved models to maximize your savings.