I have a wm 51/3 rs baxi boiler, when we turn hot water and heating on (both do not work), the boiler comes on, but after a minute or so starts to make whistling sound and then knocking, before it switches off. I was told by a plumber that it is the circulation pump, which has been replaced, but still having same problem,no heating/hot water.Can you tell me what the problem can be?

Malik, October 2008

might be an air lock check the circs coming out of the boiler 1 should be hot (top ) the other should start to get warm check the circs going into the cylinder top 1 should be getting warm as the hot water circulates. if thats not getting warm then its probably an air lock

paul the plumber, November 2008