What You Absolutely Must Avoid When Installing a Wall-Mounted Heat Pump: Real Stories from Montréal
Installing a wall-mounted heat pump is a critical step to ensure optimal comfort, long-lasting energy efficiency, and proper equipment performance. At AirGreen, we’re often called in to fix mistakes made by other installers across Montréal, Laval, Longueuil, as well as the North Shore and South Shore. These bad practices can be costly—both in money and comfort. Today, we’re sharing the most common mistakes, based on real-life cases, along with concrete advice to help you avoid the same traps.
Testimonial #1 – The Undersized Unit in Ahuntsic: A Nightmare That Could’ve Been Avoided
A triplex owner in Ahuntsic had a 12,000 BTU wall-mounted heat pump installed, even though the total square footage was over 1,400 square feet. The result? The machine ran non-stop without ever reaching the desired temperature.
The Problem:
An undersized unit drives up electricity usage, causes premature compressor wear, and creates thermal overload.
Our Solution:
At AirGreen, we performed a full thermal load calculation, taking into account the insulation, windows, and building orientation. We then recommended and installed a FUJITSU KZAH R-32 18,000 BTU model that was perfectly suited to the home’s actual needs. The result: consistent temperatures and lower Hydro-Québec bills.
Testimonial #2 – Poor Outdoor Placement in Laval: Noise, Vibrations, and an Angry Neighbor
A family in Laval had their outdoor unit placed directly on the balcony, with no vibration dampers, just 30 cm from the shared wall.
The Problem:
This caused resonant noise throughout the structure, disturbing both the residents and their neighbor.
Our Intervention:
We relocated the unit to a wall-mounted bracket equipped with acoustic shock absorbers, and positioned it at an optimal distance with proper rear ventilation. All in full compliance with Laval’s municipal regulations.
Testimonial #3 – A Sloppy Indoor Installation in Longueuil: Cracked Walls, Condensation, and Mold
In a Longueuil home, an installer drilled the wall at too steep an angle, causing condensation water to pool inside the wall.
The Problem:
This led to a slow leak, unpleasant odors, and the emergence of black mold, putting the occupants’ health at risk.
Our Fix:
We redid the wall opening with the correct downward slope to ensure natural drainage, then cleaned and sealed the cavity using anti-fungal treatments. The indoor unit (a Gree Sapphire 12,000 BTU R-32) was then reinstalled with millimeter-level precision.
Testimonial #4 – In Terrebonne on the North Shore: Missing Insulation on Refrigerant Lines
A customer called us after noticing constant droplets of water forming on the pipes of his newly installed wall unit.
The Problem:
The previous technician had failed to properly insulate the copper lines, resulting in condensation along the entire length.
Our Approach:
We removed the covers, added high-density thermal insulation, and rerouted the line to avoid unnecessary bends. The unit, a Sharp ZU1 15,000 BTU, has since been performing at its best.
Testimonial #5 – South Shore, Saint-Hubert: No Slope on the Indoor Unit
The customer had a visually flawless installation, but the heat pump was leaking on the wall after just two weeks.
The Problem:
The indoor unit had been installed perfectly level, with no incline toward the drain.
The AirGreen Solution:
Our technicians unmounted the unit, corrected the angle to a 5° incline, checked the drainage pipe, and added a backflow-prevention trap. A simple laser level check would’ve avoided this whole issue.
Pro Tips to Avoid These Common Mistakes
1. Always Perform a Thermal Load Calculation
Every home is different. A simple BTU/square foot ratio is not enough. You must consider insulation, windows, sun exposure, and number of floors.
2. Choose a Certified and Recognized Installer
AirGreen is certified by the CMMTQ and RBQ, and participates in rebate programs like Hydro-Québec’s LogisVert. Our installations meet CSA standards and follow manufacturer recommendations.
3. Ensure Proper Indoor and Outdoor Placement
Ventilation, noise, maintenance accessibility—every detail matters for durability and performance.
4. Take Advantage of Available Rebates
Many of our clients in Montréal, Laval, and Longueuil received $1,704 to $2,172 in rebates by choosing eligible models like the Gree Extreme, Fujitsu KZAH, or Bosch BIVA IDS Premium.
How AirGreen Stands Out in the HVAC Installation Field
At AirGreen, we know that installing a wall-mounted heat pump isn’t just about connecting pipes and wires. It’s a technical craft that demands precision, planning, adherence to regulations, and most of all, real-world experience.
Our team serves the entire Greater Montréal Area, from Pierrefonds to Longueuil, including Laval, Brossard, Boisbriand, and Repentigny. With our fleet of vehicles, advanced digital diagnostic tools, and proven field experience, we guarantee complete peace of mind for our clients.
In Summary: What You Should Remember for a Smooth Installation
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Never underestimate the importance of correct sizing.
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Plan unit placement carefully.
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Insulate pipes and ensure proper drainage slope.
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Work with qualified experts like AirGreen.
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Take full advantage of Quebec’s HVAC rebate programs.