Thread: Water heater supply lines both hot.

I was in a double wide today and checking a 30 gal electric water heater. I noticed that both the supply line going in and the hot line coming out were both hot at about the same temp. Never noticed this before. Any idea if and what the malfunction might be. Could it be the pipe inside that sends the cold water to the bottom is broke off and down inside?

Similar Threads:

• ABS Flue Pipe on LP Water Heater
• Tankless water heater comment
• Water Heater Location
• Water heater Question
• Reverse plumbing to water heater

Possible thermal expansion.
Water heats up in the WH and expands
If all valves are off, there is no place for the water to expand
Heated water backflows through cold water line to city water line or well.

It is possible that the hot water line has a circulator (passive or active) that causes the hot water to come back into the tank so that each faucet has hot water without waiting.

Originally Posted by Garry Sorrells

It is possible that the hot water line has a circulator (passive or active) that causes the hot water to come back into the tank so that each faucet has hot water without waiting.

Not that I know much about them, but, in a double wide?

I know this is obvious for most of us, but for the lurkers that might read this. Did you run the hot water taps immediately before checking the temperature of the hot and cold lines? Obviously if there is not movement of water through the lines, then both lines will be warm due to conduction from the tank.

Yep, ran the water, found several faucets that were reversed plumbed.

But did you check the supply and discharge pipe temperatures at the heater immediately after running the hot?

I can't see any reason for the water flowing INTO the heater to be hotter than the normal cold water temperature.

I did have a house that had hot and cold pipes running the length of the house which were wrapped together in insulation which in effect created a heat exchanger. The hot and cold became the same temperature at the far end of the house but NOT at the heater.

The only explanation I can see is if there was a recirculating function of some kind feeding hot water back into the cold water supply upstream of the place where you checked the temperatures.

Originally Posted by John Arnold

Not that I know much about them, but, in a double wide?

I agree it would be strange/unusual. But people do strange things.

I think I would go with the thermal expansion theory...... Water heats up in the tank and it heads back down the supply pipe as it expands. Now if the home has a PRV or a backflow device that shoots this theory down.