Heat Output FAQ

How much heat will I need?
We always recommend you choose radiators with a higher output than required, as you can always turn them down and have the reassurance of additional heat in really cold spells.
How is heat output measured?
There are two recognised measurements for heat output; BTU's (British Thermal Unit) and Watts. Within this brochure you will find both listed in the technical section by each radiator.
What is a Delta T?
The heat output of a radiator is established using a calculation called a delta t (�t), based on a desired room temperature of 20�c and boiler flow and return temperatures; European standards use delta t50�c as a measurement, this is based on a boiler flow temperature of 80�c and a return of 60�c (80�c + 60�c ÷ 2 - 20�c=50�c). Some systems using renewable energy sources may have different flow and returns and therefore different delta t's (e.g 60�c/40�c = Delta t30�c). If you require outputs based on alternative delta's please contact us on 01342 302250.
How can I find out what heat outputs I need?
Your installer should be able to confirm the exact requirements for each of your rooms, but you can also visit our website and use our online calculator or use the following simple calculation as a guide:
  • Find the volume of your room in cubic feet = Height x width x length (To convert cubic meters into cubic feet multiply the total figure by 35.31).
  • Multiply the volume by 6 to find the BTU requirement. If you need to know the Watts equivalent, divide your BTU by 3.412.
A bathroom 6'x8' with 8' ceilings = a volume of 384 cubic feet multiply by 6 = 2304 BTUs You may need more than 1 radiator in order to ensure an even distribution of heat in a large room, if so divide the required output by the total number of radiators you could sensibly place in the room.
e.g. a lounge 14' x 18' x 8' ceilings = 12096 BTUs.

Two radiators would require an output of = 6048 BTUs each, 3 radiators = 4032 BTUs each EN442; All our radiators are produced and outputs measured according the European standard EN442. This standard uses Delta t50�c to provide a consistent and comparative output measurement for all radiators.