Work out what kW combi boiler your home needs, based on bathrooms, bedrooms and mains water flow.
Combi size calculator
Time how long your kitchen cold tap takes to fill a 10-litre bucket on full, then divide 600 by the seconds.
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Next: what will it cost? →
Estimate the fitted price for your home.
Read the sizing guide →
Why bathrooms and flow rate matter more than bedrooms.