Thankyou very much for taking the time out to give me this detailed information, Buc.  It is appreciated.

I've read these over this evening once I've had my din dins.

Thank you for taking time to read good advice if you were nearby I'd have come to your home and gave you good advice .

But I wouldn't take on a full heating job I just do the odd boiler change which takes one day's work .

Too old for all this hard work these days .