This is a very common question but it mightn’t always the best question to be asking. A stove/boiler should be sized according to the heat demand of the room/building to be heated. It is generally not accurate to size any heating appliance, simply to the number of radiators. Any competent installer or heating engineer should be able to size an appliance correctly in accordance with room/building volumes, orientation, windows, insulation levels, etc.
Despite what some installers and retailers may tell you, it is not appropriate to determine the size of a boiler or boiler stove, simply based on the number of radiators it has to heat. We never size our stoves on this basis as there are numerous reasons that it could be inaccurate, including:
- radiators are available in a wide variety of sizes (it will take more energy to heat a large radiator than a small one)
- the radiators may not be appropriately sized for the area they're heating
- insulation may have been added to your home since the radiators were sized/installed
- your building may be more or less airtight since the radiators were sizes/installed
- rooms may have been modified with extensions, new windows or merged with other rooms, etc.
If you get in touch, we'll put you on the right track as best we can but be prepared for a few friendly questions as we try to determine the most appropriate way to size your boiler or stove.