Hottub said:O.k. thanks, I’ve now changed the diverter valve and heating and hot water working fine, did take the old diverter valve apart and all looked o.k. in there, the diaphragm wasn’t split but obviously something was wrong!
Once again many thanks for all your knowledge/help!
Wayne
Seems a bit of a waste though, a simple service kit would sort the old diverter no problem.