Where do I get printed instructions for British Gas UP1 Gas Boiler

Call British Gas. We are not them. Sorry.

Could be sludge in you system might need a flush ?

Yes if your 3-way mid position valve is stuck open. Check to see if it is in the correct position.

Boilers are inherently dangerous for the average DIY for so many reasons, contact British Gas and have them come back and fix it, tell them it was fine before the "service". They may simply have a control valve shut off.

If you are talking about the damper flap on the flue pipe. You have to go to a heating supply and buy a new flue that is already attached to a section of new pipe and fit it together. I'm not sure if your flue is free flap type of arm driven. British gas is trying to make a buck off you . Call a regular boiler repair man if you don't feel comfortable doing it your self.. Mine came apart at the hinge. The pin came out..I replaced it with a wire brad (nail) and it works just fine.

Could be divertor valve is faulty , stuck in Hot Water mode

google your boiler it comes up with a manual go to page 26 it gives you 5 reasons why it goes to f1

Any other symptoms? Is the fault apparent only when drawing hot water? Does the boiler re-light later? Alarm messages? F1? F3 for example?
It may well need a powerflush, but it's best to find out before spending big money with BG.....wish I could get away with charging that much for a flush!!!
FYV

Hi ,

Can you please tell me the model of the vaillant, and the approx age?

I can solve this problem

I await your reply

Thanks

Steve :)

Sounds like a control board or wiring to the unit has shorted out.