If you’ve decided that it’s time to buy a new boiler, you need to consider the different types available so you can ensure that you get the right one for your needs.

Boilers represent a significant financial outlay, but they are an important investment if you want a reliable and safe central heating and hot water system.

Worth the initial investment, over time, a new, more energy efficient boiler will save you money on your heating bills.

Before you decide on which type of boiler is most suited to your property, consider the following points:

The most common boiler sizes

How many people live in your house? How many radiators does your boiler need to feed?

Boilers come in a variety of sizes, here are four of the most popular:

  • 24-25kw – suitable for flats and houses with 2-3 bedrooms, with up to 10 radiators
  • 28-30kw – suitable for 3-4 bedroom properties with up to 15 radiators
  • 33-35kw – suitable for larger houses with up to 20 radiators
  • 40kw – as above


Where do you want to install your new boiler? How much room do you have?

The most cost-effective option is to have your new boiler installed in the same place as the one you’re replacing, as the pipes needed will already be in place. However, you need to consider space for a cylinder and possibly a tank too, depending on the type of boiler you choose.

Energy efficiency

By law, all new boilers must be a ‘condensing’ type in order to meet energy efficiency requirements.

Warranty and parts

Does your boiler come with a warranty, and if so, how long is it? What does it cover? What is the cost and availability of parts if something goes wrong when the warranty has expired?

Scrappage schemes/grants

It’s worth doing some research into old boiler scrappage schemes or any funding that might be available if you’re replacing your boiler.

System flush

Check the terms of any warranty offered, as it may be invalid if you don’t also have your system flushed during installation, to remove the build up of sludge that can occur over time.

Water pressure

It’s essential that your cold water flow rate is tested to ensure that it can cope with the minimum requirements for combi boilers.

Installation time

Depending on the type of boiler you choose, installation time can be anything from a day’s work to two or three days. If you’re converting from a system boiler to a combi boiler, expect to be without heating and hot water for at least one day and night.