I have a Turco Combi boiler that I installed in 2003. There has been a problem since day one. Its been working fine and as the problem does not affect me, I have never bothered to fix it. So here goes .... 1. Central Heating On ... No problem with the heating, it works just fine 2. Central Heating Off ... No problem with Hot Water, it works just fine 3. Central Heating On ... Heating works OK but Hot water is tepid when used As I live alone, I have always turned the CH off before taking a shower or filling a bath. Now I am selling the house and would like to fix the problem before selling Before I go out and buy a Diverter valve, has anybody got a comment or suggestions. Thanks in advance.