Why does every other post on here get treated with such contempt? Nothing in the OP suggested he was going to DIY, yet I see more and more responses on this forum which are either suspicious, or just downright offensive. His follow up response clarifies the situation nicely, if there was any doubt to begin with (personally, I can't say there was, even having re-read the OP multiple times).
If the OP had written something like this:
http://www.ukplumbersforums.co.uk/central-heating-forum/94385-confused.html
Yes, go ahead and blast him. But don't turn away legitimate questions because you've come across one too many DIYers in your time.
Most threads on here are DaftyDIYers doing DIY gas work & the Google Warriors like Bernard Green are falling over themselves to give them & dangerous information.
Most GS registered RGIs like me will only charge about £65.00/hour + vat. But no they're too tight to pay that & think they're bright enough to DIY??!!