wrote in message
oups.com...
That is true, but more expensive: additional coil in cylinder = £40,
heat exchanger = £100-150

Not a lot at all, in fact buttons, when you look at the efficiencies of the
two.

thanks all I'm OK for now.

would recommend heatweb.com for
unusual cylinder requirements (until I
receive my estimate maybe?)

Not cheap. If you have a specification many other companies can quote.