The water heaters are set up with the DRAINS connected BEFORE the drain. I could not find where the line went from there.
Why would this be done… the homeowner did not know.
The bottom line running over the wall is where this connected drain is running. It may have been used to serve the bathroom on the other side… hard to tell.
It likely a gravity return loop to improve availability of hot water at the most remotely located fixture which is where you may find the third line begins.
There be a recirculating pump located somewhere as well.
Copied from the above site:
It works in this fashion in your house. You already have half of the loop in place. This is your hot water piping distribution system which begins at your hot [FONT=arial,trebuchet,verdana,sans-serif]water heater[/FONT]](Hot Water Recirculating Loop) and ends at the farthest [FONT=arial,trebuchet,verdana,sans-serif]fixture[/FONT]](Hot Water Recirculating Loop) which requires hot water. If you were to install copper piping leading back from the farthest point and from other high points in the existing system, you would have a loop. This return loop connects into the bottom of the hot water heater where the current drain valve is located. It is that simple.
Looks that way to me, Mike.
It would not be a supply line, the water in the bottom of the tank being cold.
It is an awkward location for return lines and not necessary IMO. Tapping into the cold supply down tube at the top of the tank should accomplish the same thing, less confusing for inspectors, less likely to get knocked loose. :neutral: