"Bodgit" wrote in message
oups.com...

Looking again at the plate with the serial number etc. on it, the model
number is Jet 70/90. Now I've looked on the internet at other makes, I
think I can assume that the 70/90 refers to the number of 1000s of
BTU/h. So I think it should be possible to get 90,000 BTU/h or 26KW out
of it. Is this a reasonable assumption?

I think that it refers to the input and output, ie 90000 BTu's input
70000BTU's output, thus 20000BTU's goes out the flue.

Don't take my word for this it could be BS!

Julian.