How does my boiler work?

Have you ever wondered – how does a combi boiler work? Or even – what is a combi boiler? Our simple guide to central heating systems explains the good, the bad and the ugly of the most common types of boiler. So you can understand which is right for you and your home.

What are the main types of boiler?


Combi boiler:

A combi (or combination) boiler is by far the most common type of boiler. A combi boiler system's simple design requires little space in your home and supplies hot water directly to your taps or radiators without the need for a storage tank.

The chief advantage of a combi boiler is its economy. Because it supplies hot water on demand, you only ever pay for what you use. So it means it's highly energy efficient and also financially efficient.

Conventional boiler:

Unlike a combi, a conventional (or regular boiler) uses two water tanks – one to draw the supply from the mains and one to feed the system and manage the expansion of the heated water.

If you're replacing a boiler in an old property, this can be a good option as it requires little alteration to the existing pipework. The main drawbacks of a conventional boiler though are:


  • Conventional boiler systems are relatively complicated and take up a lot of space

  • They store your hot water in a cylinder instead of supplying hot water on demand

System boiler:

Like combis, system boilers take water directly from the mains. Unlike combis though, system boilers store the water they heat in a tank. So although a system boiler uses less space than a conventional boiler system, it's more complicated than a combi and needs more room.

Now you know how it all works

OK so you're practically an expert on what makes your boiler tick. That's great. Now all you need to do is make sure you insure and service your boiler. You never want to be left without heat and hot water and sometimes you won't be able to fix the problem, so boiler insurance is a must. Similarly, you should get your boiler regularly serviced. This could catch any problems, before they become a problem.

Boiler Protect

We've teamed up with trusted supplier Intana to offer EDF Energy customers boiler cover from only £8.69(1) per month. You can get your cover here.

Boiler response

If you have a boiler emergency, you can call Intana 24 hours a day on 01444 442 882(2) for boiler response from £99. Full details on Boiler Response are available here.

Boiler service

Keep your boiler running safely and smoothly with a service from as little as £80. Call 01444 442 882 or find out more here.

Boiler replacement

If your boiler is beyond repair, you could have a new boiler installed the very next day (if you order before 3pm) learn more here.