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  • Writer's pictureWest Street Plumbers


Updated: Apr 19, 2021

If you want to know how many KW your boiler sould be then you can use this simple calculator as a guide. If you have:

· Up to 10 average size radiators and 1x bathroom* you will require a 24kw to 27kw combination boiler.

· Up to 15 average size radiators, 1x bathroom and 1x ensuite* you would need a 28kw-34kw combination boiler.

· Up to 20 radiators and 2x bathrooms* you would need between 35kw and 42kw.

For properties where a higher demand of hot water is needed the higher the kw of the boiler and thus the better the flow rate of hot water will be. Also remember that if your rooms are the size of football pitches, you will need more radiators and thus a larger boiler.

*This is based on a combination boiler. Combis are small and mighty but do not cope well with 2 showers/baths running at the same time in the same property, If this is likely to be an issue, check our boiler guide. Please remember that boilers should only be fitted by a Gas Safe Engineer and it is always advisable to go through a trades vetting site such as Checkatrade.

How many radiators are enough?

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