An oversized central heat pump might seem, at first glance, like a smart choice. More power must mean better performance, right? However, in the world of residential and commercial HVAC, this misconception is the root cause of many issues, inefficiencies, and financial losses. At AirGreen, as specialists in central heat pump installation across Montréal, Laval, Longueuil, North Shore and South Shore, we regularly encounter this problem during on-site assessments. Here’s why choosing the right capacity is critical—and what you risk by installing a system that’s too powerful.
Why Oversizing Is So Common in HVAC Projects
A Reflex of Overprotection Against Harsh Québec Winters
The harsh winters of the Greater Montréal area often push property owners to demand a system more powerful than necessary, thinking it will guarantee comfort. This misguided precaution is sometimes encouraged by inexperienced contractors or vague quotes without proper load calculations.
Lack of Thermal Load Calculation
The heat load (or thermal loss calculation) is an essential first step before any central heat pump installation. Yet some contractors skip it or eyeball it. The result: a poorly sized system that performs poorly—whether it’s undersized or oversized.
The Real Consequences of an Oversized Heat Pump
Short Cycling That Hurts Efficiency
An oversized heat pump quickly reaches the desired temperature... and then shuts off. This short cycling is counterproductive: each restart uses more energy than continuous operation. This leads to:
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Higher electricity consumption (and higher bills)
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Premature wear of components
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A significant reduction in system lifespan
Constant Thermal Discomfort
Contrary to what you might think, more power doesn’t mean more comfort. A system that’s too strong heats or cools the air quickly, but doesn’t run long enough to control humidity levels. The result: a sticky or clammy atmosphere, typical of poor climate control.
Noise Pollution and Overheated Ductwork
The blower units of an overly powerful central system can push too much airflow through an existing duct network, causing:
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Excessive noise
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Annoying vibrations
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Potential overheating or poor air distribution
Real-World Examples Observed by AirGreen in the Field
Project in Laval – 60,000 BTU Goodman Central Heat Pump Replaced
In a 1,200 sq. ft. bungalow in Laval, we were called to assess a 60,000 BTU Goodman heat pump installed four years earlier by another company. Reported issues: discomfort, excess humidity in the summer, high energy bills. After conducting a full HVAC performance assessment, our team determined the home’s actual thermal load was just 36,000 BTU.
We installed a Bosch BOVA36 unit (36,000 BTU, SEER 20, HSPF 10) with smart modulation. Since then, electricity usage has dropped by 22%, and comfort has drastically improved—especially thanks to better humidity control.
Commercial Call in Longueuil – Undersized Ductwork
A commercial client in Longueuil complained of excessive noise from their HVAC system. The 5-ton system installed in a 2,000 sq. ft. building was far too large for the ductwork’s capacity. Result: whistling sounds, pressure loss, and uneven temperatures across the office. We recommended a 3.5-ton central heat pump with a revised air distribution network. Performance and comfort improved immediately.
How to Avoid This Problem: AirGreen’s Best Practices
Performing a Certified Thermal Load Calculation
Before any central heat pump installation, our team carries out a detailed energy analysis that includes:
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Living area, orientation, insulation levels
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Window types, air leaks
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Heating AND cooling needs
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Building occupancy
This assessment lets us determine the optimal capacity of the system.
Choosing Variable-Speed Models
Modulating central heat pumps (such as the Bosch IDS Premium series or FUJITSU KZAH R-32 models) adjust their performance continuously based on real-time demand. This eliminates short cycling, improves efficiency, and reduces noise.
Helping You Access Available Grants
We help you maximize your return on investment by guiding you through Hydro-Québec’s LogisVert rebates, as well as municipal and federal incentives. Installing a properly sized heat pump gives you access to:
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Up to $5,000 in financial assistance
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20 to 40% annual energy savings
Mistakes to Avoid at All Costs
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Installing an HVAC system without an energy assessment
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Automatically choosing the most powerful model
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Reusing an inadequate duct system without modifications
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Trusting a contractor who never mentions thermal load calculations
Why Choose AirGreen for Your HVAC Installations in Montréal and Surrounding Areas?
At AirGreen, our mission is simple: deliver reliable, efficient, and customized HVAC solutions, whether you’re located in Montréal, Laval, Longueuil, the North Shore or the South Shore. Every project includes a precise diagnosis, personalized guidance, and installation that meets the highest industry standards.
Our expertise is built on hundreds of successful installations of central heat pumps from Fujitsu, Bosch, Goodman, Lennox, Trane, and many more. We don’t just sell BTUs—we deliver smart, economical comfort, year after year.
In Summary
Choosing an oversized central heat pump is like buying a truck to do your groceries: inefficient, noisy, expensive, and uncomfortable. With AirGreen, every project is custom-designed based on your real needs, whether for your home or your commercial building.
Don’t compromise your comfort or your budget. Trust HVAC professionals who take the time to do things right.