The cost of running a combi boiler for one hour depends on several factors, including the model, its efficiency rating, and the current cost of gas. On average, a 24 kilowatt boiler costs around 91 pence to run for an hour at full capacity, based on typical UK gas prices.

However, most boilers do not run continuously at full output. In practice, intermittent heating cycles and modulating features reduce the actual hourly cost. For general domestic use, most households spend between £3 and £5 per day on heating during colder months.