Water Heaters - Hot water only out of faucet

hi just came across this forum. here's the story.

my house on the second floor has hot water only coming out of the hot and the cold from the faucets.

however, downstairs, there is only cold water and no hot water from the hot and the cold faucets.

we have two small water heaters and an expansion tank side by side downstairs.

do you guys know what can cause this?

Perhaps one tank serves each floor and one tank is not operating.
Run the hot water on each floor and feel the line leaving each tank.
Maybe a breaker has has tripped or the elements are gone in one tank.
There could be a reset button for the offending tank.

hmm. thanks for the reply.

i'm pretty sure both water heaters work. i turned the thermostat on both of them up, and they both make noises like its heating.

they are single element water heaters.

even if one was broken, wouldn't it just not heat the water? why would the cold water faucet have hot water coming out. even the toilet is using hot water to flush.

if one of the water heaters weren't operational, would the cold water line turn into a hot water line?

i have a feeling that the hot water is backflowing in to the cold water line or something like that. does that make sense?

this just started happening yesterday, with nothing changed. thanks for the reply. :thumbup:

btw, both tanks i think are connected to each other. they serve the whole house, but we recently remodeled the downstairs and tapped into the hot water line. of course this was a few years ago.

both tanks feel hot too. so i think they both work.

Hello: tominos

Back flowing is a possible cause because or more likely because the two tanks are connected in tandem. Than to an expansion tank. Check for a backflow device. May not be working correctly.

Another rare cause but possible is a defective faucet. Some faucet designs allow a cross flow of water. The cross flow is internal beneath the faucet. When one of the shut offs becomes defective, it can allow a cross flow. Usually hot into cold.

Another is excessively hot water. Excessively hot water expands so much it will back flow into the cold lines as the pressure increases above that of the incomming cold water. The tanks should have pressure relief valves as well as an expansion tank.

Especially if the tanks are used for room or space heating. Which in this case not likely to be. However, not common in this area to have an expansion tank, so I am not totally familar with expansion tank installations....:( Only familar with the properties, principles and theroy of hot water and expansion.

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hmm. well i can say that the faucets are not defective, because all the faucets in the house have turned into hot water. what's weird is that downstairs, which is pretty close to the water heaters, has no hot water, it is at most lukewarm while upstairs the water is hot out of both cold and hot lines.

i will check for an anti flow device. thanks alot