Two hot water lines serving water heater

[Elizabeth Chambers]

I was looking at the water heater in a house my neice is renting. She insists that both the water lines are hot feeding the water heater. I felt them and they both did feel hot. Only one had a shut off valve on it. This makes no sense to me (sorry no pictures yet).

Why would both lines be hot when one serves the house fixtures after the water is heated and the other should feed cold water to the tank to be heated. I am thinking maybe the cold water line feels warm because it is positioned right next to the exaust vent connector?
Could that be a possibility? Otherwise wouldn't the water heater become too hot and cause the tpr valve to discharge all the time?

[Dom D'Agostino]

Plenty of water heaters have warm or hot pipes near the tank. The heat from the hot water inside the tank flows with or through the water, and metal pipe (if present) makes an excellent conductor. Maybe the heat traps/check valves were left off or are ineffective.

Typically the cold side inlet has a shut off valve, but it could be on both sides.

Other factors at play could be pipes routed in a warm/hot space (attic, such as a re-pipe) that would change the temperature.

Dom.

[Gunnar Alquist]

I was looking at the water heater in a house my neice is renting. She insists that both the water lines are hot feeding the water heater. I felt them and they both did feel hot. Only one had a shut off valve on it. This makes no sense to me (sorry no pictures yet).
Why would both lines be hot when one serves the house fixtures after the water is heated and the other should feed cold water to the tank to be heated. I am thinking maybe the cold water line feels warm because it is positioned right next to the exaust vent connector?
Could that be a possibility? Otherwise wouldn't the water heater become too hot and cause the tpr valve to discharge all the time?


Like Dom said, heat will conduct through the pipes. One way to check is feel both pipes, then turn on the hot water faucet in a nearby bathroom or kitchen and feel both pipes again. Water will flow into the tank from the cold water supply and cool off the cold water inlet pipe. The pipe with the shutoff valve *should* be the cold water inlet and cool down at this point.

[Jim Luttrall]

Like Dom said, heat will conduct through the pipes. One way to check is feel both pipes, then turn on the hot water faucet in a nearby bathroom or kitchen and feel both pipes again. Water will flow into the tank from the cold water supply and cool off the cold water inlet pipe. The pipe with the shutoff valve *should* be the cold water inlet and cool down at this point.
Agreed.

[Elizabeth Chambers]

Ok guys I will do that and see whats up. Thanks

[John Kogel]

Get a laser thermometer. They are fun to use and make you look even more professional. :D

In this case, you would actually see the measured temp difference once you start drawing hot water thru the pipe.