Radiator efficiency

[Ronob]

I Have been looking around for a new radiator for a conservatory and amazed by the huge difference in "claimed" BTU levels. It wold appear that a 400 x 1200 type 21 double rad can vary by as much as 1000BTU that is about 20% of the highest claim.

Is there really that much difference between standard convector rads? I don't know what the internal technicalities are but the ones I've seen all look very similar like the standard Stelrad brand

 

[Charnwood]

I think that may be contrary to building regulations.
Someone more qualified will be along soon to clarify this, no doubt.

 

[D_Hailsham]

It would appear that a 400 x 1200 type 21 double rad can vary by as much as 1000BTU that is about 20% of the highest claim.

I expect there is a simple explanation. Can you provide some examples, preferably with links to the sites.

P.S Using BTU is like still using pounds, shillings and pence; the current "currency" is Watts.

 

[Dan Robinson]

The referenced temperatures may well be different for different brands.

 

[Ronob]

Thanks for the input guys. It appears there are two types of double radiators which seems to make the difference - I learn something every day!