When a Poor Wall-Mounted Heat Pump Installation Leads to an Energy Disaster: A Real Case from a Duplex in Longueuil
At AirGreen, we pride ourselves on providing professional, durable, and efficient HVAC installations. However, we are all too often called in after poorly executed—and sometimes disastrous—installations. The case study we present here involves a wall-mounted heat pump that was improperly installed in a residential duplex in Longueuil, and the consequences were severe: electricity bills doubled, persistent thermal discomfort, and premature replacement of the unit. Here's a detailed breakdown of this shocking case, showing why a professional HVAC installation makes all the difference.
Initial Context: An 18,000 BTU Wall-Mounted Heat Pump Installed Without Expertise
Initially, the owner of a duplex located in a growing residential neighborhood of Longueuil hired a company offering an attractive price to install an 18,000 BTU wall-mounted heat pump, from an obscure brand, without a proper thermal evaluation of the property.
From the very first summer season, problems started to appear:
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Uneven indoor temperature between the two floors.
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Abnormal energy consumption, confirmed by Hydro-Québec billing.
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Unusual noises and wall vibrations.
After several months of discomfort, the owner reached out to AirGreen for a full diagnostic.
Complete Diagnostic by Our AirGreen Team in Longueuil
Upon arrival, our team identified several glaring issues:
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Incorrect sizing of the unit: the model installed didn’t match the real heating and cooling needs of the duplex.
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Improper slope of the condensate drain, leading to water infiltration and moisture inside the walls.
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Poorly mounted indoor unit, causing vibration and noise disturbances.
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Outdoor unit placed in a poorly ventilated area, resulting in constant overheating and drastically reduced performance.
Our team also discovered that the unit had been connected to a non-compliant electrical circuit with no dedicated protection—posing a real safety risk.
Consequences: Overconsumption and Discomfort
Because of this poor HVAC installation, the client saw their electric bill double during the hottest months. The wall-mounted heat pump, misconfigured, ran continuously without ever reaching the set temperature. Furthermore, residents in both apartments experienced constant discomfort: too hot upstairs, too cold downstairs.
AirGreen’s Intervention: Replacement and Professional Reinstallation
After discussing options with the owner, we proposed a complete solution tailored to the layout of the duplex:
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Installation of a Gree Lomo 18,000 BTU wall-mounted heat pump, with Inverter technology and high energy efficiency (20 SEER).
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Full thermal assessment of the areas to be cooled and heated.
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Complete revision of the electrical circuit, including the addition of a dedicated breaker.
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Precise installation of the indoor unit, with corrections made to the wall structure.
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Optimal placement of the outdoor unit, with enough clearance for effective natural ventilation.
The intervention took a full day. We paid particular attention to the aesthetic finish of the piping and the maximum reduction of vibrations.
Results: Reduced Costs and Restored Thermal Comfort
Just one month after our intervention, the owner observed:
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A 43% reduction in electricity consumption related to the heat pump.
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A uniform temperature between both floors.
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Quiet and stable operation of the unit.
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Increased rental value of the duplex thanks to a reliable, high-performing HVAC solution.
Key Takeaways: Mistakes to Avoid During an HVAC Installation
This situation illustrates several common mistakes:
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Skipping a thorough thermal assessment: every building has unique requirements.
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Hiring an uncertified or inexperienced installer: initial savings can cost much more in the long run.
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Neglecting post-installation maintenance and inspection.
Best Practices Recommended by AirGreen
To avoid situations like this, we recommend:
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Requesting an on-site assessment before purchasing a wall-mounted heat pump.
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Always choosing a recognized brand for reliability and energy efficiency.
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Ensuring the installation meets all electrical and structural codes.
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Scheduling annual maintenance to maintain optimal performance.
AirGreen’s Expertise in Longueuil and Across the South Shore
At AirGreen, we regularly intervene in Longueuil, Saint-Hubert, Boucherville, Saint-Lambert, and across the South Shore to correct or optimize poorly designed HVAC installations. Our approach is based on transparency, technical precision, and attention to detail. With our expertise, you can not only improve comfort but also achieve long-term energy savings.
Make the Right Choice from the Start
Thinking about installing a wall-mounted heat pump in Longueuil or on the South Shore? Avoid costly mistakes by working with a certified, experienced team. At AirGreen, we guarantee a compliant, safe, and optimized HVAC installation.