What Size Boiler For My House?

Choosing the right size combi boiler for your home can be bewildering, and whilst it is advisable to consult a Heating Engineer or Gas Safe Plumber to give you advice on your selection it is useful to have an idea of what you will need for budgeting. We have given a rough guide below to help you plan.

What size boiler for my house?

Combi boilers are available in three size ranges here at Mr Central Heating; 24 to 27kw, 28 to 34kw and 35 to 42kw.

  • As a rough estimate most flats, apartments and smaller houses, with up to 10, average size radiators and 1 bathroom* will require a 24 to 27kw Combi Boiler.
  • For a medium to large 3-4 bed house with up to 15 average size radiators, 1 bathroom and an ensuite* a 28-34kw Combi Boiler would be installed.
  • A 35kw and a 42kw Combi boiler would be for a large house with anything up to 20 average size radiators and 2 bathrooms*.

For properties where a higher demand of hot water is needed the higher the kw of the boiler, the better the flow rate of hot water will be.

*However combi boilers do not cope well with 2 showers running at the same time in the same property. Where this is a requirement a system boiler with an unvented cylinder should be considered.

What is a Combi boiler?

A combi boiler (or to give it it's full name a combination boiler) is the name given to a boiler that provides heat for central heating and heats water instantaneously on the opening of a hot tap.

With a combi there are no tanks in the loft and no storage cylinder. The water is fed from the mains so the water pressure is generally greater.

This information is not going to be accurate for every property as room sizes can vary wildly from property to property, but will give you a good idea when consulting with a heating engineer over your needs.

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