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Les pires cas de surdimensionnement qu’on a vus… et ce que ça a coûté aux clients
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The Worst Cases of Oversizing We've Seen... and What It Cost Our Clients

The Consequences of Incorrect Sizing: A Lesson for Homeowners

At AirGreen, we often deal with heat pump systems that have been improperly sized, sometimes by less experienced installers. An oversized system might seem like the perfect solution at first, but it can lead to performance issues, comfort problems, and energy inefficiency. In this article, we’ll share the worst cases of oversizing we’ve encountered and explain what these mistakes cost our clients. We will also give you tips on how to avoid these pitfalls and ensure your HVAC installation is perfectly suited to your needs.

Oversizing a Heat Pump: When More Isn’t Better

One of the most common problems we encounter during our interventions is oversizing central heat pump systems. Contrary to what you might think, a heat pump that’s too powerful for a home can lead to a number of negative consequences, including:

  • Higher energy consumption, as the unit operates in shorter, less efficient cycles.

  • Uneven thermal comfort caused by fast heating or cooling cycles that don’t allow for a uniform temperature.

  • Premature wear on the unit because it doesn’t run continuously, preventing optimal energy management.

Example #1: A 2000 Sq. Ft. Home in Laval

In a project in Laval, a client had installed a 6-Ton Gree Extrême heat pump, a high-capacity model, for a 2000 sq. ft. home. The oversizing seemed like a precaution against the cold winters, but after installation, several problems arose:

  • Short cycles: The heat pump was running briefly, not allowing enough time to heat the entire house evenly.

  • Increased energy bills: Despite the unit’s power, electricity bills increased by 30%.

  • Uneven comfort in certain rooms, especially the upstairs bedrooms that remained cold during winter.

Solution to the Problem

We adjusted the system by replacing the oversized unit with a 4-Ton Gree Extrême heat pump, better suited to the home’s actual needs. Additionally, we balanced the ductwork to improve airflow. The result: reduced bills, uniform comfort, and optimized performance.

Example #2: Oversizing in Longueuil with a Bosch BOVA Heat Pump

Another notable example occurred in Longueuil, where a family opted for an 8-Ton Bosch BOVA heat pump for their 3000 sq. ft. home. Although the house size justified a fairly powerful system, the installed model was far too large.

The consequences of this oversizing were immediate:

  • Compressor failure: The unit frequently tried to restart quickly, leading to overheating and frequent breakdowns.

  • High energy bills: While the house was well heated, the heat pump’s efficiency was reduced due to the short cycle.

  • Excessive noise, as the unit operated intermittently, with abrupt starts and stops.

Solution to the Problem

We replaced the unit with a 5-Ton Bosch BOVA heat pump. By adjusting the capacity, we allowed the unit to operate more efficiently and continuously, reducing costs and improving overall comfort.

Why Oversizing Is Problematic: Understanding the Basics

It’s essential to properly size the heat pump to match the specific needs of the home. Key factors to consider include:

  • The size of the house: The larger the space, the more powerful the heat pump needs to be, but not excessively so.

  • Home insulation: A well-insulated home will need a smaller heat pump than a poorly insulated one.

  • Windows and the home’s orientation also play a key role in calculating energy needs.

How to Avoid Oversizing?

At AirGreen, we follow a strict approach to avoid any oversizing:

  1. Accurate thermal assessment: We perform a full analysis of heating and cooling needs, considering insulation, windows, and the home’s orientation.

  2. Choosing the right capacity: We always recommend a heat pump suited to your space, ensuring it’s not excessively powerful.

  3. Professional installation and maintenance: Proper installation and regular maintenance ensure that your unit functions properly and maintains energy efficiency.

Conclusion: Why Proper Sizing Makes All the Difference

Oversizing is not just about higher initial costs, but it can also harm your energy efficiency and comfort. By choosing the right model, properly sized and installed by professionals like those at AirGreen, you maximize energy savings, improve thermal comfort, and reduce your carbon footprint.

If you have any questions about your heat pump’s sizing or would like a free evaluation of your heating and cooling system, don’t hesitate to reach out. AirGreen is your trusted partner for effective and tailored HVAC solutions.

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