I need to replace my central heating system and currently, the radiators are flat panel cast iron radiators, 60 cm high, some three section (120cm), some four section (160cm).
I need to decide whether to keep these or replace with steel ones but I need to know what the heat output of the existing ones is.
Two specialist cast iron radiator sites (castironradiators.ltd and castrads.com) give the output as about 320w per section for a 60cm high rad but the Zylo guide seems to say that for a flat panel cast iron radiator the output is 820 W/section which is not far short of 3 times the output quoted by the other sites.
If Zylo is correct, I may be ok with the current ones, otherwise they will need replacing. Can anyone tell me the correct value?

I need to decide whether to keep these or replace with steel ones but I need to know what the heat output of the existing ones is.
Two specialist cast iron radiator sites (castironradiators.ltd and castrads.com) give the output as about 320w per section for a 60cm high rad but the Zylo guide seems to say that for a flat panel cast iron radiator the output is 820 W/section which is not far short of 3 times the output quoted by the other sites.
If Zylo is correct, I may be ok with the current ones, otherwise they will need replacing. Can anyone tell me the correct value?