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.

Note: 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. You can also check out our "Find a Boiler" guide at http://www.mrcentralheating.co.uk/find-a-boiler

8 thoughts on “What Size Boiler For My House?”

  • I am about to start building a Pssive Spec house and need advise as to what size boiler I need.
    Tel 07970 911778

  • Currently my water gets cold real fast when i am taking a shower. What is a good size boiler for a 1 and 1/2 bedroom medium house

  • Hi, I need advice on what boiler wattage I require for a ground floor 4 bedroom flat? It is a council block and it has 3 floors above me. 1 bathroom with electric shower

  • What power gas boiler would I need for a 4bedroom house

  • for 3 bedroom House and 2 bathroom ,1 first fl and 1 to loft,1 kitchin with 10 radiators what size boiler I need!thank you!Daniel,

  • I have 3 bathroom with 3 showers. What bolier is best? Dont have space for a system bolier with tank?

  • We are about to build a 5 bedroomed, 4 bathroom and cloakroom house, approximately 4,333 sq ft
    What type of boiler would be recommended, the ground floor will have gas supplied underfloor heating. 1st and 2nd floor radiators.

    • Hello Angela,

      As your house it quite large, you would be better asking a plumber to come around and asses. You can use our installer database to help find a local plumber


      Thanks Mr Central Heating

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