Today I learned that if you have TRV’s fitted on your radiators, at least one of the radiators in your house much have standard valves on it and these should be left fully open. This is to create a bypass in the event of all the TRV’s being switched off or failing. Without this bypass, the boiler would start making a knocking sound and is likely to overheat.
It pays to talk to your British Gas engineer when they come over! :smile: