How to Size a Pool Heat Pump?

A common question that consumers ask us at Wotech when shopping for swimming pool heat pumps is: “How big does my heat pump need to be?” You should have a trained swimming pool professional size your swimming pool heat pump, as its size will depend on many factors. There are, however, general formulas we provide to our customers to approximate heat pump size. We explain how to use these formulas in this article. Wotech, a professional pool heat pump manufacturers in China for 13 years, cooperated with many worldwide companies and brands, aims to provide high efficient and green energy for environment protecting.

What to consider?

Size of your pool--size a swimming pool heat pump size a swimming pool heater

The size of your pool is one the most important things to keep in mind when sizing a pool heater. And this is because the amount of water a heat pump needs to heat (the size of your pool) directly correlates to how powerful it needs to be.

So by that logic, the bigger your pool (volume), the stronger/bigger your heat pump should be. When you size a pool heat pump, you need the surface area of your pool, which is easy to find and explained later in this post. That said, although pool size is important, it’s not the only factor to consider.


Where you live (climate)

Equally important as the size of your pool, is where you live. Specifically, the climate. If you live in a climate that’s mostly warm year round, then most of the time, your pool heat pump won’t have to work all that hard. For someone with an average sized pool, using a smaller to standard sized pool heat pump would be ideal.

On the flip side, for pool owners living up north or in more diverse climates, it’s a little bit different. If your pool has to brave all 4 seasons, then it’s important to know how cold it can get during the swim season.This is because of the way pool heat pumps work. Since they harvest the natural heat in the air, they tend to perform best in warmer climates. But a heat pump can still do its job even in cold weather. It just has less starting heat to work with, so to compensate, it works a bit harder. In fact, heat pumps like the Oasis Platinum are designed to run all the way down to outside temperatures in the 30s —most other heat pumps usually cut off around the 50-degree mark.

In fact, heat pumps like the Oasis Platinum are designed to run all the way down to temperatures in the 30s —most other heat pumps usually cut off around the 50-degree mark. Pool heat pumps with advanced low-temperature performance, like the Oasis Platinum, can help pool owners in colder climates stretch out their pool season even longer.

The third factor

So with your location and pool size in mind, what’s left to consider?

Your swimming habits.

Do they factor into the actual calculations needed to size a heat pump? Not really. But if you’re someone who’s in the pool almost every other day, then heating speed may be important to you.

Well, with a stronger pool heat pump comes stronger heating ability. So even if you’re already in a fairly warm climate, it can sometimes make sense to choose a stronger unit if you’re in the pool often and have the extra room in your budget.

Of course, pool heat pumps by nature are designed to provide resilient, and reliable heating in a full range of climates. So even with a standard sized heat pump, you can’t go wrong.

And on that note, let’s get to what you came here for.

How to size a pool heat pump | What size pool heater do I need

You may not realize it, but you’re already halfway done. Yup, with your pool size and location in mind, you have 60% of the information you need to size a pool heat pump.

Of course, for the sake of accuracy, you’ll still need to do a little math. But don’t worry, it’s a really simple formula.

I usually accurate like below:

Heating Capacity= [(Swimming Pool Square)m³*1.163* (Output Water Temperature - Input Water Temperature)]/ Heating Time


This is roughly heating capacity, you need to add 30% as heating loss.

So for example, the pool size is 20*26*2m, Input water: 26℃, Output water: 28℃, heating time, the needed heating capacity formula as below:

KW= (1040m³*1.163*2℃)/24h=100kw=340000Btu

30% Heating loss: 100*1.3=130kw

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