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St Albans Brighton Islington
Clapham Leamington Spa

Choosing the right heat output for your radiator

How do I calculate the heat output of a room?

Begin with our simple heat calculator which will give you a guide to the heat required for a specific room. However, always get a second opinion from your plumber or heating engineer as they will be able to take into account any elements that might potentially impact the heat. There are more complex calculations for properties that have specific issues due to age, location, heating system etc. so if you think your property will have issues, ask a heating consultant to do the necessary calculations.

The heat outputs of your chosen radiators are unlikely to be exactly the same as your heat requirement. We recommend you choose a radiator size with a higher rather than lower heat output and fit thermostatic radiator valves so you can control the room temperature. It is always better to have too much heat than not enough.

Why do you show outputs as Delta 50 (Δt 50ºC)?

The heat output range is shown in watts and BTUs (British Thermal Units).

Wattage is based on the system’s likely operating temperature and is shown as Delta 50 (Δt 50ºC) which is the current European Rating.

In our experience, most UK plumbers and heating engineers may still calculate heat requirements using the older, original British Delta 60 rating. To avoid any confusion, please use the conversions below or feel free to contact us.

To convert Delta 50 to Delta 60, multiply Delta 50 heat output by 1.264
To convert Delta 60 to Delta 50, divide Delta 60 heat output by 1.264
To convert BTUs to Watts, divide by 3.412
To convert from Watts to BTUs, multiply by 3.412

How do I calculate the heat needed in a conservatory?

In a conservatory, there are a number of factors that will affect heat loss, including the quality of the glass and how much glass there is. Your plumber or installer will give you an accurate estimate of the heat output you will need. If you would like us to help, speak to a member of our team.