Heating System Output Calculator

The following calculators can be used to create an approximate total heat out from radiators or circuits, that can be used to range rate or set modern boilers in order to improve efficiency. Shown further below will be articles to specific boilers to adjust the heating load total.

Instructions for use: Please first use the radiator output calculator to work out the watts produced by a radiator. Please note the delta T is defaulted to 50°C  ie operating on Flow, Return and Room Temperatures of 80°C, 60°C and 20°C respectively or 75°C,65°C,20°C respectively. You may change the Delta T to suit your calculations.

Radiator Output Calculator


Copy the radiator output to the boxes below to produce a total for the heating system.

Total Output Calculator

Disclaimer: Information on this website is provided for informational purpose therefore we cannot accept liability for subsequent problems. All repair tasks should be carried out by qualified trades people. We may also receive commission payments when you are taken to external websites and complete purchases from third party sellers, once you leave our site, we cannot be held liable for your purchases.