Originally Posted by ukmark
The black valve. It goes from a red line to a blue one. Check to see if that valve is closed. If it's open,when you turn on cold water, the hot water, from the HWH, will go into the blue line and then to your sinks or toilet.
The top one needs to be open, that feeds your HWH. The valves allow you to bypass the HWH, when winterizing. You might have forgotten or missed closing that valve.
The valve at the bottom should be open. I'm guessing it is, cause your getting hot water everywhere