Before you can select a boiler, you will need to have a proper heat load calculation performed. We take the dimensions of the room including the ceiling height, insulation value along with window sizes and from there we calculate how many kilowatts (kW’s) are required to heat the room. Once each room has been calculated we had up all the kilowatts and that will give you the total kilowatts required to heat the house.

You will find if you get a few quotes that everyone has a unique way of calculating how many kilowatts are required. Generally, if the difference is a few hundred watts is nothing to be concerned about but if there is a significant difference it would be worth further investigation.
The most common size boilers that we use are around 30kW. A common question is what if your house only requires a total of 12 kW – why would I put in a boiler that can do more than double the kilowatts that I need? All boilers today can be adjusted to provide the number of kilowatts you need. For example, if you house only requires 12 kW we would turn the boiler down to do maybe 14 or 15 kW. This way you are not using excessive gas than required. Of course, should you may be designed to extend the house, and on a few rooms, the additional radiators that you install may require another 5 kW. Your boiler can then be adjusted up to say 21 kW.
Hopefully that all makes sense? If you have any questions, feel free to send me an email. You can access all the brochures for the boilers that we use by clicking on this link.