If you have a swimming pool in the UK, it stands to reason that you’ll want to heat it. Unfortunately, it is rarely warm enough here to get away with swimming in an unheated pool, so if you want to make maximum use of the facility, finding the right size of boiler to heat the water is essential.

So, what size boiler do you need to heat your swimming pool? After all, getting the choice right is essential for efficiency and efficacy. Here, we take a closer look at the considerations when choosing the best size of boiler for your pool.

Calculating Your Swimming Pool’s Surface Area

The first step when it comes to deciding on the correct size of boiler to heat your pool is to calculate its surface area. This isn’t as complicated as it sounds. Work out how long your average pace is, then pace the width and length of your pool. This allows you to determine its surface area.

It’s important to know what your pool’s surface area is because its surface determines how much heat can pass through into the pool and also how much warmth can escape on cold days. A bigger pool surface area means that you’ll need more BTUs to keep your pool water at a warmer temperature than the air.

Work Out Your Basic BTU Requirements

A BTU or British Thermal Unit is the amount of heat needed to increase 1lb of water’s temperature by 0.55 degrees Celsius or 1 degree Fahrenheit. You need to know how many BTUs your pool requires to determine the best boiler for your needs. You can work this out in the following way:

Once you know your pool’s measurements, you need to divide its area by three. So, for example, if your pool has an area of 360 square feet, the BTU requirement is 360 divided by 2, which is 120. This gives you a basis to work from.

Working Out Your BTU Requirements In More Detail

Next, you need to fine-tune this figure.

The perfect BTU rating for your boiler will depend on several factors including:

  • Whether your pool has a relatively low or high humidity profile
  • The night temperature on average through the year
  • How much the water surface is disturbed by the wind
  • The average temperature of the air where your pool is located

You can incorporate those factors into your calculation by:

1. Deciding how warm you want your pool to be when its thermostat cuts out

2. Working out what the average temperature of the air is on the coldest month you’ll be using your pool

Subtract number 2 from number 1 and this tells you how much you need to heat your pool.

You’re now ready to work out your theoretically ideal BTU rating. The equation you need for this is

(The amount you want your pool temperature to rise by) x (the surface area of your pool) x 12

You’ll need to know the following figures:

  • The average wind speed at your pool’s surface is 3.5mph.
  • You’re looking at a temperature rise of 0.5 – 0.7 degrees Celsius per hour

Needless to say, it’s quite complicated to work all of this out yourself, but you can present a specialist in pool boilers with these details, and they can help you find the right boiler for you.

Helping Your Pool Boiler to Work Most Effectively

Once you have the right pool boiler for your needs, there are a few more things you can do to maximise its effectiveness. It can be hard to keep your pool warm all year round, especially in the winter, but you can add a thermal pool cover to keep more heat in, or even totally enclose it to maximise heat retention.

Getting Professional Advice

As you can see from the advice above, it isn’t easy to work out which kind of pool boiler you’re going to need. There are so many factors to take into consideration, and the formula is quite complex to calculate. It, therefore, makes sense to ask an expert in the field for their professional advice.

The Rowlen team are on hand to offer their expertise in this area. With more than half a century of experience in this industry, we are the professionals you need to help you select the optimal pool boiler for your requirements.

We offer a fully comprehensive service, from working out precisely what you’ll need, to installation and ongoing maintenance. You can even count on us to service your pool boiler annually to keep it functioning at its optimal level for many years to come. Don’t hesitate to get in touch with the Rowlen team today and let us help you to find the right size boiler for your pool.