Replacing your boiler is a daunting task and finding the right one for your home is a big part of the reason why. When we refer to the “size of a boiler” we don’t even mean how big the boiler is, boiler “size” actually means what kind of output the boiler has in kilowatts (kW).
The right size of boiler for your home is not a one size fits all. We’d love to tell you it was so you could instantly find the right boiler, but there are a lot of factors that go into sizing your boiler properly that makes it just too difficult. However, what we can do is give you the best advice we can to help you make the best, most informed choice.
Things to Consider
There are multiple factors to consider to make sure you get the right boiler size. Generally, this comes down to:
- The number of radiators in your home
- The number of bathrooms
- The number of people in the home (or the general demand for hot water).
Considering these factors together should give you a great starting point for deciding what size boiler you need, but any Gas Safe engineer that knows what they’re doing should be able to take everything into account, plus any other outlying factors, such as how size or layout of your home, and help you make a decision.
A final consideration to think about when it comes to the right size of your boiler is your boiler type. Installing a system or regular boiler for example means you need to consider the size of your cylinder(s) as well.
Rough Boiler Sizes
Broadly speaking when all these things are factored in you can get yourself into the right ball park for boiler sizing.
Roughly you can expect that if you want a combi boiler then:
- Up to 9 radiators, 1 bathroom and 1-4 people in your home will need an up to 29 kW boiler
- 10-15 radiators, 1-2 bathrooms and 4-6 people in your home will need a 30-45 kW boiler
If you want a system boiler then:
- Up to 10 radiators, 1-2 bathrooms and 1-5 people in your home will need an up to 20 kW boiler
- 11-20 radiators, 1-4 bathrooms and 4-8 people in your home will need a 21 – 40 kW boiler
And if you want a regular boiler then:
- Up to 10 radiators, 1-2 bathrooms and 1-5 people in your home will need an up to 20 kW boiler
- 11-20 radiators, 1-4 bathrooms and 4-8 people in your home will need a 21 – 40 kW boiler
