[royboy0349]

Can anybody help me?? I am getting hot water going into my cold water tank, and this is causing water to come out the overflow. If I run the hot water tap it stops, and then when the hot water tank has filled again, the cold water tank overflow starts again.

[mygirlsdad77]

Not sure exactly what you setup is, but it sounds like you need a check valve between the hot and cold water tank with a thermal expansion tank between the hot water feed and the check valve.