Hi

Please excuse a newbie question.

I have a Potterton 50e still working well. The trouble is, the join
of one of the two main water feed pipes has had a very slow leak.
This has dripped down and corroded the outer casing.

We have had an engineer round who has patched up the hole with fire-
cement - but wants to sell us a new boiler now. Is this really
necessary? Does the outer casing need to be fully air-tight? It is a
big expense we weren't expecting.

Thanks in advance.
Olly