Estimate the heating capacity required for your home or specific rooms.
House Dimensions
sq ft
ft
Heating Capacity
Enter details to estimate heating capacity
About this calculator
Overview
Selecting the right boiler size is crucial for energy efficiency and comfort. A boiler that is too small won't heat your home properly, while one that is too large will waste fuel and wear out faster due to short-cycling.
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Pro Tips
If you're upgrading your insulation (e.g., attic or wall insulation), you may be able to use a smaller, more efficient boiler.
For combi boilers, the hot water demand is often the deciding factor for the kW rating.
Always consult a qualified heating engineer for a professional heat loss calculation before purchasing.
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Fun Facts
"Modern condensing boilers are over 90% efficient, compared to older models that were only 60-70% efficient."
"Oversizing a boiler is a common mistake that can lead to higher energy bills and increased maintenance costs."
"The term 'BTU' stands for British Thermal Unit, which is the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit."
