Pool Heat Pump: Is There a Benefit to Oversizing?

Swimming is more enjoyable for everyone when the pool water is heated. Heat pumps are an energy-efficient and effective way to warm up the pool water, with many types and sizes of pool heat pumps available. Choosing the right size of a pool heater for your pool is a careful decision you have to make.

However, if your present pool heater does not meet your pool requirements, you’ll need to figure out how to size your pool heater pump correctly. Can you oversize a heat pump? This is the question we will be discussing in this article.

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Can You Oversize Your pool Heat Hump?

If you have been looking for the answer to this question, it is a big yes. Pool heat pump owners are familiar with “bigger is better.”

You should generally oversize the heat pump to the greatest extent practicable. You’ll never regret getting too big because it allows you to heat the pool more quickly without using the heater as much.

With that said, there are a few things to know before you engage in oversizing.

Determine how fast you want the water to be heated. 

Generally, the faster your pool heats up, the higher the output level. Before you try oversizing your pool heat pump, make sure you are working within the specified range (50,000 to 150,000 BTU). 

Make sure you have the required energy.

Heat pumps use a huge amount of electricity to operate, which is one of its biggest shortcomings because it affects your budget greatly. Yet, they’re still less expensive to run than gas heaters.

You should also double-check your electrical arrangement, as heat pumps require between 50 and 60 amps to operate.

Set your desired water temperature.

Most pool owners prefer water that is between 82 and 86 degrees Fahrenheit. Due to their reliance on the outside temperature for the level of BTU production, heat pumps can only create so much heat and will eventually top out (especially smaller pumps).

On warm days, though, you should be able to heat your pool to 82°F.

Does your pool have a solar cover? 

Since the surface of the pool water (any other water body) is where most of the heat escapes, it’s a requirement to have a solar cover. Solar covers keep the heat in, allowing you to use a smaller pump less frequently.

They also prevent water from evaporating, reducing the amount of money spent on pool maintenance. Solar covers are available in a variety of sizes and shapes. 

What is your swimming frequency? 

You should only leave the pool uncovered for roughly 2 hours every day if you want to optimize the heat in your pool while keeping your electricity bill low.

In which months do you go swimming?

In the summer, electric heat pumps are most effective. They draw warm air from the outside and inject it into the water. Heat pumps are most effective from May through September.

Running them once the temperature drops below 50°F are futile because there isn’t enough warmth in the air to transmit to the water.

What is the maximum amount you are willing to pay? 

Pool heat pumps are substantially less expensive to operate than gas pool heaters, but they are also much more expensive to purchase. Furthermore, a heat pump may not be the most cost-effective solution if you reside in a region where electricity is expensive. 

As with all pool heaters, if you go big, you’re golden. A smaller pool heater pump size won’t necessarily be detrimental, but you’ll have to run it longer and may have problems keeping the pool warm.

The factors mentioned above are the most important determinants of proper sizing. That being said, there is no easy way to determine the exact size of heat pump you’ll need for your pool.

When it comes to pool heat pumps, though, going big is always a good idea. Though purchasing a smaller heater is not detrimental, you might need to allow it to run for a longer time, and it can be challenging to maintain the swimming pool warmth.

How do you Size your Pool Heat Pump?

It should be worth noting that some external factors (cited below) play a role in how fast your heat pump warms your pool water. 

  • the size of your pool
  • the outside temperature
  • the humidity level
  • the amount of wind

To keep these outside factors from influencing your pool water temperature, you will have to size your pool correctly.

There are two ways you can go about properly sizing your pool heat pump:

You can simply follow a chart that shows the available amount of BTUs needed when using a heat pump. In this way, it is easy to choose a pump that will work well with the amount of water in your pool.

In this method, there are some calculations that you will need to do. Guess you don’t hate figures. For better understanding and simplicity, follow the steps below.

  • Determine by how much you want to increase your pool temperature. For example, let’s assume your pool has a temperature of 50°F and you want to raise it by 20°F. That is taking it up to 70°F. 
  • Then, you will have to determine your pool’s surface area (SA). Again let’s assume your pool has the dimensions 20ft by 10ft giving a total surface area of 200 square feet.
  • Finally, you can calculate the right values needed for your pool using the equation below.

S. A x the temperature Increase x 12

Note that 12 is the minimum BTU Needed.

200 x 20°F x 12 = 48000BTUs

Therefore, you will need a 48000BTUs heat pump output to increase the temperature of your pool.

Learn How to Manage Your Pool and Hot Tub

Frustrated trying to keep your pool clear? Feeling confused about when to add the right chemicals? Get the perfect easy-to-use, illustrated ebook and video course today!


In general, it is always best to oversize your pool heat pump as much as possible. This helps you use the equipment quickly to raise your water temperature yet have your desired result.

This leaves us to support the common pool owners saying that “bigger is better” or “bigger is golden.”

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