When it comes to your swimming pool, all the parts need to be size appropriate. Everything from your filter to your skimmer baskets will need to be a sensible size or the whole system is affected. When it comes to a heat pump, get that wrong and you will find yourself unwilling to step into the pool.

Depending on your needs, the smaller heaters on the market will still work unless you have a larger pool but will take longer to heat. This makes them more economical in the long run. Your type of pool will also determine the size of the heat pump you need. A swimming pool that has an attached spa will need something a little more powerful.

We’re going to take a look at the different types of heat pumps and sizes.

What Is BTU?

BTU (British Thermal Unit) is the output per hour that a heat pump offers.

Finding the right output is important but those with greater BTU output aren’t always right, even if your pool is bigger. How frequently you use it and for how long will also play a big part.

What Are The Different Types of Pool Heat Pumps?

Before you think about what size pool heat pump you need, it might be better to consider the type of heat pump first. This will determine how much you want to spend on the device itself and on energy bills.

The following are the most common.

Gas Pool Heater

There are two types within this category, you can get propane gas heater and natural gas heaters for pools. They both have their benefits and are considered to be the most powerful of at-home heating systems. In terms of BTU, they average at around 100,000 to 400,000 but you can buy even higher BTU output as well.

Electric Pump

These heat pumps don’t work in the way you might expect. Instead of heating from an element, they use the ambient air around the device to heat the water returning to your pool. It is considered to be one of the most cost-effective methods of heating a swimming pool but that depends on how often you use it.

Solar Pool Heater

Solar pool heaters might be better for the environment but they do have a low BTU output compared to the previous two methods. Technology is always changing and advancing but of course, when you need to heat your pool, there is less sunlight. Solar power can be sued alongside other methods to take the strain off and reduce energy bills. The initial outlay of installation and materials can be high and is a stumbling block for many people who would like to use them.

Gas Pool Heater vs Electric Heat Pump

Low Temperatures

One of the areas that an electric heat pump isn’t as effective is when the temperature of the water drops below 50 F. When this happens they tend to struggle to bring the temperature back up because they use the ambient air which will, of course, be a lot colder, it might be a long time until you feel the effect.

Gas pool heaters tend to excel no matter what the starting temperature of the water. If you live in a particularly cold climate or have harsh winters, this is definitely something to consider if you want to use your pool for swimming.


There are two things to consider here. The upfront cost and the running expenses. For the initial payment, a gas pool heater tends to be cheaper than an electric heat pump.

However, the running costs of gas are higher than electric so your bills will be affected. If the ongoing cost is a big factor, then this is where solar heaters can be a sensible choice. Again though, this all depends on how often you are going to use the pool. If it is infrequent, the running cost probably isn’t going to have much of an effect, but you will want something to heat up fast, like gas.

Consider what type of gas you intend to use as well as natural is cheaper than propane.


For both, installation is relatively easy. Gas can be plumbed into your home’s gas line although you should always consult an expert or leave it to the professionals. Installing an electric heat pump is often considered to be even easier.


For anyone in a milder climate, an electric heat pump system will likely be more than strong enough to cope with the conditions. However, gas represents a sensible purchase for those who need something that heats fast and has a higher BTU output.


A gas pool heater will be noticeably noisier than an electric heat pump which will set about its work discreetly.

How Often Should I Heat My Pool?

This is all down to your preference really. Again though, it should also influence the type of pool heat pump system you buy. If you are planning on heating your pool infrequently, then you want something that will heat up fast. If you need to keep the temperature at a constant heat, then a gas system might be preferable as it slowly heats the water.

Again, if you are looking to heat it slowly then a smaller heat pump might suffice, but if you only plan on using it a couple of evenings a week, then a larger pump that heats quickly might be best.

What Size Heat Pump Do I Need For My Pool?

Most experts will advise a BTU output of 50,000 BTU’s per 10,000 gallons of water. Larger pools such as those around 60,000 gallons will need the greater BTU’s to heat. This is where the big 400,000 BTU heaters come into effect.

How Can I Help My Pool Retain Heat?

To make your pool heat pump more efficient, consider using a pool cover. This traps the heat and it is great to keep the temperature raised overnight. This will save you money on the next day and beyond if you use it continually.

If you are only using your pool on the weekend, it can be energy efficient to maintain the temperature during the week. Keep it lower than you would have it before you consider getting in, then increase the temperature on the weekend.

Using windbreakers around the pool can help as the wind can significantly reduce the temperature of the water. Also, you should keep an eye on the temperature using a thermostat. Not only will this help you find the optimal temperature that you feel comfortable with, but it will also allow you to see when the pool water is unnecessarily high so you’re not wasting money when you aren’t using it.


Whist you should match the size of your heat pump to the size of your pool, you should also consider how often you will use the pool. A lot of people buy bigger heat pumps for their swimming pools, use it in the following months then as the novelty wears off, they won’t get in again until the summer.

For the infrequent user, there is no need to spend more than you need but whatever you choose, buying a pool heat pump will allow you to get extra months use out of your pool, and make you popular with your friends who will want to come over for a soak.

Remember to turn the heater off when you are going away or if you think you aren’t going to use it for some time. Your utility bills and the environment will thank you.