I have suffered from pump over since I replaced a seriously sick pump about 3 years ago. I have an old vented C/H system with a Potterton Netaheat boiler. As I could not cure the problem I had decided to live with it whilst reducing the effects as much as possible, i.e. putting a cover over the header tank to stop the condensation soaking the loft. Anyway I decided to have another look this morning and noticed there was a short (1 metre)15mm pipe run teed into the flow side of the pump and teed into the exit side of the immersion tank pipework. There is a stop valve midway along this pipe which was open and when I closed it the pump over stopped immeadiately. Can anyone tell me the purpose of this "bypass" and assure me that I have not done anything I should'nt? Have I really cured my pump over by closing this valve?. iIt will certainley make my Xmas if that is the case.
Thanks
D