Hi, I have an Ideal Isar He30 Boiler had it for about 3 years serviced a couple of times once when S trap was blocked.
My issue know is when the DHW heatplate randomly heats and the boiler fires up T operation, the boiler vibrates like a low frequency drum for about 10 seconds till fully up and running, it doesnt do this when either using C central Heating or Drawing hot water from tap, just does when firing up on T operation a plumber told me you can disable this operation but cant find a way of doing this or what is the cause of this problem.
Would be grateful for help on a fix.
Regards John