Choosing the Wrong Heat Pump: A Common Trap in Residential Projects Across Québec
In the field of residential HVAC in Québec, properly sizing a wall-mounted heat pump is far from a minor technical detail. On the contrary, it's a critical factor that directly impacts indoor comfort, energy consumption, and the unit's durability. At AirGreen, we regularly encounter situations where a miscalculation or poor assessment of needs has led to a problematic installation. That’s exactly what happened in this single-family home in Laval, where we were called in to fix an installation done by another contractor.
A comfortable home… until the wrong heat pump arrived
The owners of this home, located in a quiet Laval neighborhood, contacted us at the beginning of fall after enduring a hellish summer—despite having a brand-new wall-mounted air conditioner. Their unit, a basic 9,000 BTU wall-mounted heat pump, simply couldn’t maintain a stable temperature on the main floor. The result: stifling days, sleepless nights, and a strangely high electricity bill for a supposedly energy-efficient appliance.
Technical diagnosis: a capacity issue, not a brand issue
Our evaluation team visited the site to perform a complete thermal analysis. Within minutes, the problem was crystal clear: the installed heat pump wasn’t sized appropriately for the main living area, which exceeded 800 square feet. Even a high-performing 9,000 BTU model cannot effectively cool a space that large. As a result, the unit was constantly running in overdrive, leading to premature wear, excessive power consumption, and continuous discomfort.
We also noticed that the outdoor unit had been installed too close to a poorly ventilated brick wall, restricting airflow and further reducing the system’s performance.
AirGreen’s intervention: expertise, sizing, and restored comfort
After clearly explaining the situation to the homeowners and taking the time to answer all of their questions, we recommended replacing the unit with a Fujitsu KZAH 18,000 BTU model—a system known for its reliability, performance in both cooling and heating, and suitability for Québec’s harsh winters. This unit uses the R-32 refrigerant, which is more eco-friendly and more efficient than the traditional R-410A.
Here are the key steps of our intervention:
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Safe removal of the previous unit.
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Professional vacuuming of the refrigerant line.
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Optimized wall-mounted installation of the new heat pump, respecting the required clearances.
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Full vacuum and refrigerant charge in accordance with the manufacturer's specifications.
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Performance testing across several complete cycles (heating and cooling).
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Customer education on how to get the most out of their new heat pump and maximize energy efficiency.
The result: a transformed home
Just hours after the installation, the owners felt the difference. The properly sized and carefully installed Fujitsu KZAH unit delivered stable, soft, and even temperature, without excessive noise or uncomfortable fluctuations. They were also thrilled to learn that this model qualified them for a $1,704 LogisVert grant from Hydro-Québec, thanks to its high energy efficiency rating and certified professional installation.
Common mistakes to avoid when choosing a wall-mounted heat pump
At AirGreen, we always stress the importance of a personalized assessment before any installation. All too often, we are called in afterward to fix avoidable mistakes. Here are a few essential tips for homeowners:
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Don’t base your choice solely on price or brand: just because a unit is “powerful” doesn’t mean it’s the right fit for your home.
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Demand a full thermal load calculation: this step is essential to determine the correct BTU capacity.
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Ensure the installation is done to code: poor placement or lack of clearance can drastically reduce efficiency.
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Hire a certified installer: this ensures not only a safe installation but also eligibility for government grants.
Why choose AirGreen?
We don’t just sell machines—we offer HVAC solutions. Every installation is personalized, every project is analyzed in depth, and every client is listened to with care. Whether you’re in Montréal, Longueuil, on the North Shore, or the South Shore, our team will support you from start to finish with one simple goal: to ensure your comfort, in every season, with no unpleasant surprises.
Our installers are trained, certified, and passionate about their work. And we’re proud to fix others’ mistakes when it means restoring comfort for a family.
Conclusion: one small wrong choice can change everything
A poorly chosen, improperly installed, or neglected system can turn a cozy living space into a true thermal nightmare. That’s why at AirGreen, we take every project seriously—no matter how small. Because behind every wall-mounted heat pump, there’s a home, a family, and a life we aim to improve.