Boiler Overheating

[I've created a new post for this as it might have been overlooked as part of the more general topic in which I originally posted.]

I moved house about seven months ago and have had no problems with our gas boiler until the last few days. It keeps overheating and automatically shutting down, which means I have to manually reset it again. I've tried turning the valve down that's under the panel on the front, but it makes no difference. Now, whenever the boiler comes on (like this morning at 5 o'clock), there is a loud tapping/thumping noise coming from underneath our bedroom floorboards (where the pipes run). CH is not on, and hasn't been for months, this is just occurring for water heating.

Any help would be appreciated because I'm dreading a hefty bill.

As a quick fix, turn down the stat on the boiler.

Regards - J

Thanks for your quick reply. Are you talking about the knob on the PCB (that appears to be the only manual control on the boiler)? If so, I've already tried turning it down halfway, should I turn it further?

Cheers.

Hey Tony - you're not the Tony Lee involved with Renault dealerships....... are you? If so, send me an email.
John

Not me mate, sorry.