I would appreciate some help with my Alpha 240e combi boiler. I have had problems with the diverter valve in the past but I have serviced this and appears to be working fine for the last 6 months or so. The problem I now have is that after running nice hot water for about 5 minutes the boiler seems to overheat or for whatever reason shuts down and won't re-start until it has cooled down for about 15 mins. I have checked the pump and it seems to be working. The pump continues to run on when the central heating circuit goes off but doesn't with the DHW circuit (don't know if it should). I'm getting fed up with the shower going cold half way through and then not being able to get hot water again !! Any ideas with what could be wrong would be great.