When we turn on the hot water tap the boiler fires up but instead of water coming out of tap being hot (its lukewarm at best) the radiators start to get hot. I suspect that water heated in the combustion chamber is not being diverted to the secondary heat exchanger but instead circulating in the central heating. The boiler is not cutting out and then cycling back so I am pretty sure the heat exchanger is NOT blocked. Sounds like the diverter valve is not functioning properly. Thoughts on what and how I should check would be greatly appreciated. I image problem could be electrical as well as mechanical.
Last edited: