Understanding the gap between rated performance and real-world energy use with your wall-mounted heat pump
At AirGreen, we’re often contacted by clients in Montréal, Laval, Longueuil, the North Shore, and the South Shore who are surprised to see their energy bills go up, even after installing a wall-mounted heat pump that’s supposedly among the most energy-efficient on the market. So how do we explain this discrepancy between the efficiency rating (SEER or HSPF) and actual power consumption? In this article, we’ll guide you through a detailed analysis, based on our real-world experience, to help you understand — and avoid — this situation.
A high energy rating… but only in ideal lab conditions
SEER (Seasonal Energy Efficiency Ratio) and HSPF (Heating Seasonal Performance Factor) are calculated under ideal lab conditions: stable ambient temperatures, no wind, no sun or frost exposure. In reality, Québec’s climate conditions — thermal fluctuations, freezing temperatures, high humidity — are a far cry from these benchmarks.
Real example:
A client in Brossard had a 12,000 BTU wall-mounted Midea heat pump installed and complained of higher energy consumption in January. Upon inspection, we found the unit was constantly entering defrost mode, which significantly impacted performance. This type of behavior is never factored into SEER/HSPF testing.
Improper heat pump sizing: a common and costly mistake
Many clients choose oversized models “just to be safe.” However, an oversized heat pump quickly reaches the set temperature and shuts off, only to turn back on shortly after. This start-stop cycling leads to:
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Excessive electricity use
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Premature compressor wear
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Inconsistent comfort levels
On the flip side, an undersized unit runs constantly trying to keep up, driving the energy bill way up.
A poorly executed HVAC installation can destroy system efficiency
We were called in urgently to Laval to reassess an installation done by another contractor, where an 18,000 BTU Gree wall-mounted heat pump was drawing way too much power. After inspection, we discovered:
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The condensate drain was poorly positioned, causing water buildup that triggered protection mode in the unit.
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The refrigerant line was too long, exceeding manufacturer specs and disrupting the cooling cycle.
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No insulation on the liquid line: energy loss between the compressor and the evaporator.
At AirGreen, we strictly follow all manufacturer specifications for every HVAC installation, ensuring tight sealing, precise calibration, and maximum energy efficiency.
Skipping HVAC maintenance: a major contributor to excess consumption
A poorly maintained wall-mounted heat pump is one that consumes more energy. Here’s what we often find when clients ask us for a diagnostic:
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Clogged filters restricting airflow
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Dirty evaporator coils, reducing heat exchange capacity
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Dust buildup in the fan, lowering overall performance
We recommend a yearly HVAC maintenance appointment, including:
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Cleaning of filters, coils, and drain
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Refrigerant pressure check
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Thermostat calibration
Housing-specific factors: sunlight exposure, insulation, and windows
In a recent project in Saint-Eustache, we replaced an older 15,000 BTU Sharp heat pump with a newer model. Despite the upgraded unit’s high efficiency rating, the homeowners were still experiencing high energy usage in the winter. Why?
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Poorly insulated windows
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Full exposure to northern winds
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Uninsulated attic
Even the best wall-mounted heat pump can’t compensate for major heat loss in the home.
How AirGreen helps you avoid these mistakes
In-depth thermal analysis before installation
We conduct a personalized thermal study that takes into account:
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Room volume to heat/cool
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Insulation quality
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Orientation and sunlight exposure
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Access conditions and ambient noise levels
Rigorous equipment selection
We never choose a heat pump based on brand or price alone. Our selection considers:
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Actual required BTU output
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Low-temperature heating capacity
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Sound level
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Eligibility for LogisVert, RénoClimat, and other grants
HVAC installations done by the book
Our technicians follow a strict protocol:
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Proper slope for the condensate drain
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Exact measurement of refrigerant piping
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Leak testing using nitrogen
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Full vacuum pull on refrigerant lines
Client Testimonial: Optimized installation in Longueuil
"After two winters with a heat pump that seemed energy-hungry, we called AirGreen. Their diagnostic was extremely thorough. They reinstalled a 12,000 BTU Fujitsu KZAH model, perfectly sized for our condo. Since then, our Hydro bill has dropped by 28%."
— Mr. Girard, Longueuil
Practical tips to optimize your energy consumption
Always hire a certified expert
Installing a wall-mounted heat pump isn’t a DIY job. It requires expertise in:
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Refrigeration
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Electrical systems
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Thermal dynamics
Monitor your consumption in the first few weeks
If you notice:
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Frequent on/off cycling
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Unstable room temperatures
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Unexpected spikes in energy use
Reach out immediately for a complete HVAC diagnostic.
Conclusion
At AirGreen, we believe a high-performing wall-mounted heat pump, when properly installed, calibrated, and maintained, should never come with surprise energy bills. Thanks to our field experience and recognized HVAC expertise across Montréal, Laval, Longueuil, the North Shore, and the South Shore, we’re here to help you achieve comfort, long-term savings, and reliable system performance.