DIY Doctor UK DIY Forums

Looking for help. I have recently moved into a 3 storey house with a combi boiler on the ground floor. The basin on the third floor has plenty of pressure and flow but the flow does not fire the boiler (a Vaillant). If I turn a kitchen tap on low then boiler fires and the water upstairs is hot.

I am baffled, since the flow is good, why the boiler does not fire. Any ideas? Is the flow switch adjustable? It beats me.

paulus22

Possible the diaphragm in the diverter has split or become stretched - replacing this - and maybe the fulcrum arm - will solve the problems.

htg

Thanks for the advice, just a couple of questions. Are these readily available parts - swapped on a diy basis, or are they part of a replaceable unit. Since it is in the water system, presumably you don't need to be Corgi registered to do this kind of thing - just an amateur plumber?

paulus22