Boiler broken 3 weeks after service

[RhubarbAndMustard]

I don't really know what kind of guarantees you get, if any, after a boiler service, but we had ours done 3 weeks ago which included replacing the pressure valve. Our boiler has now broken- if I turn it on, the pressure needle swings wildly and it makes banging and clonking noises which sound awful so I switch off immediately.

Should this really happen 3 weeks after their service or are we just unlucky?

Unlucky.

Same way as if the head gasket fails on your car on the way back from a service.

They don't strip and check every component

Just unlucky. Used to happen to us regularly.

unlucky, where i work we would go back out foc upto a month after the service, but if it wasnt caused by the service you would be charged.

Unlucky I'm afraid but you're not alone.
11 days after our boiler was serviced the PCB failed, for the second time in 6 years.

you mean the pressure relief valve, which squirts water outside the house if the pressure goes too high?

these most often need replacement if they drip, usually after repeated pressure faults have opened them and scale or dirt has accumulated on the moving parts.

The pressure gauge behaviour you describe suggests there is still an underlying pressure problem. Perhaps the vessel needs pumping up. Were you aware of previous pressure problems?

You're spot on Piglet. The outside pipe kept blowing out orange/brown water which is why we wanted the fix/service originally. I didn't know of any pressure issues before that.

orange/brown water means the system is rusting inside. Probably because it has been repeatedly topped up with fresh water.

I'd suggest:
(A) fix the cause
find out if the pressure vessel needs pumping up, or replacing

find out if there is a leak, or if the filling valve is letting by

(B) prevent further damage
have a system filter added to capture the rust and corrosion particles before they can build up into a blockage

have a cleaning chemical (you can get long life ones now, for use with the filter) and a corrosion inhibitor.