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How Do I Calculate What Size of pool Heat Pump I Need?

By adding a heat pump to your pool, you can extend your swimming season, ensuring warm water even as the temperature drops. However, choosing the right size heat pump for your pool is crucial to ensure efficient heating and optimal performance. In this guide, we'll explore the steps to help you calculate the perfect size of pool heat pump for your swimming oasis.

Understanding Pool Heat Pump Sizing

When it comes to sizing pool heat pumps, it's essential to consider their heating capacity, usually measured in British Thermal Units (BTUs) or kilowatts (kW). This capacity determines the heat pump's ability to efficiently heat your pool water to your desired temperature. By understanding how heat pumps are sized based on their heating capacity, you can make informed decisions to ensure optimal heating performance for your pool.

Steps to Calculate Pool Heat Pump Size

This guide outlines the steps for sizing a pool heat pump. By following these steps and consulting with a pool expert, you can choose the perfect heat pump for your needs, keeping your pool warm and enjoyable all year round.

1. Determine Pool Volume: Measure the length, width, and average depth of your pool. Use these measurements to calculate the volume in cubic feet or gallons.

To determine your pool volume, we require some essential information from you:

  • Pool Shape: Please specify the shape of your pool (rectangular, oval, kidney-shaped, etc.), as this will help us apply the relevant formula accurately.
  • Dimensions: Provide the length, width, and depth of your pool in either feet or meters.
  • Average Depth (Optional): If your pool has varying depths, providing an average depth measurement will suffice for estimation purposes.
  • Water Features: Inform us about any water features inside the pool, such as infinity edges, waterfalls, jets, or other special features, as they can affect the heat pump size selection process.

Once we receive this information, we can calculate your pool volume and offer guidance on selecting the appropriate heat pump size. Below are common pool shapes and their corresponding volume formulas:

Rectangular Pool: Volume = Length x Width x Depth

Oval Pool: Volume = (Length x Width x Depth) x 0.55

Circular Pool: Volume = (π x Radius² x Depth)

Kidney-Shaped Pool: Divide the pool into sections (rectangular, triangular, etc.), calculate the volume of each section separately, and then sum the volumes of all sections for the total pool volume.

For accurate assessments, especially for complex pool shapes or unique environmental factors, we recommend consulting a pool professional. They can provide expert advice tailored to your specific requirements.

2. Calculate Temperature Rise: The desired temperature is a pivotal aspect in selecting the appropriate pool heat pump. Here's its significance:
  • Determine the desired temperature increase for your pool. Subtract the current water temperature from the desired temperature to find the temperature rise.
  • Heating efficiency is crucial. An undersized heat pump may struggle to maintain your desired temperature, while an oversized one can be inefficient and costly. Aim for a pump that can increase the temperature by 0.20-0.25°C per hour.
  • Environmental factors like wind, pool covers, and surroundings affect heat loss. Consider these factors when selecting a heat pump; you may need a slightly larger one to compensate.
  • In colder climates, you may need a stronger heat pump for effective heating.

3. Use a Sizing Chart or Calculator: Most manufacturers offer sizing charts or online calculators to assist in selecting the right heat pump size based on your pool's volume and desired temperature increase. Input your pool's specifications to get an estimate of the required heating capacity.

Madimack offers a pool heat pump sizing calculator to assist you in making the best decision for your pool. Gain comprehensive insights into running costs, heater sizing, unit dimensions, space requirements, and more instantly with our pool heat pump calculator.

Heat sizing calculator:

4. Check the COP rating: The Coefficient of Performance (COP) rating indicates the efficiency of a heat pump. A higher COP means better efficiency, translating to lower operating costs. Look for heat pumps with high COP ratings to ensure energy-efficient pool heating.


  • A COP of 1 means no efficiency gain; COP 2 means 1 kW of electricity generates 2 kW of heat.
  • Modern heat pumps typically have COPs from 3 to 7. Advanced models like the InverECO Heat Pump can reach higher values, with a COP range of 10.8 - 6.2.
  • When comparing heat pumps, consider their COP ratings under your typical operating conditions for a well-informed decision.

5. Consult a Professional: While online calculators can provide a rough estimate, consulting with a pool heating expert is advisable for accurate sizing. They can consider all relevant factors and recommend the most suitable heat pump size for your specific pool.

6. Consider Additional Factors: Consider other factors that could impact sizing, like wind, humidity, or whether you use a pool cover.

Selecting the right size pool heat pump is essential for efficient heating and enjoyable swimming experiences. By understanding the factors involved and following the steps outlined above, you can accurately calculate the size of heat pump needed to keep your pool comfortably warm. For expert guidance and assistance in choosing the perfect pool heat pump for your needs, trust Madimack. Our expert team is ready to assist you in maximizing your swimming season with dependable and efficient pool heating options.

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