How many watts does a radiator emit?

sandy700

How many watts does a double radiator measuring 500mm by 600mm with a water temperature of 50 deg C  emit?

matelodave

As as rough idea use the calculator here - Panel Radiator Output Calculator | Castrads .

However you also need to derate the radiatior as the calculator assumes that the deltaT (difference between rad temp and room temp) is 50 degrees C which it wont be with a flow temp of 50c . It will only be 50-20 = 30 degrees .

You need to apply a correction factor - using the calculator you get a heat output of about 538 watts at a deltaT of 50C  (double panel rad*) to which you have to apply a correction factor of 0.513 = approx 273 watts

*Its a bit more if you've got a double panel convector rad (if its got fins between the panels)

Have a look here for correction factors - Stelrad Correction Factor - Stelrad

FreeBear

Correction factor for a ∆T (Delta T) of 30° C is 0.515. Depending on whether your radiator is a type 21 or type 22, the rated output with a ∆T of 50°C will be something in the region of 700W to 880W.

A ∆T of 50°C assumes the water temperature is at 70°C.... So with a water temperature of 50°C, your radiator will output 360-450W of heat or about the same as 27 cats or 4 humans.

QrizB

One of these is nominally 2916 BTU/hr, 855 watts:

https://www.screwfix.com/p/flomasta-type-22-double-panel-double-convector-radiator-600-x-500mm-white-2916btu/798xp

But that's at a radiator temperature of 50C above ambient, so 70C in a room at 20C.

If your radiator is at 50C in a room at 20C, so 30C above ambient, the output will be 30/50ths of the nominal value - so 513 watts.

FreeBear

QrizB said: If your radiator is at 50C in a room at 20C, so 30C above ambient, the output will be 30/50ths of the nominal value - so 513 watts.

Bit less than that. This page has a calculator you can use - https://www.clyderadiators.co.uk/delta-t-conversion