Water heater filling from HOT side while draining...but how?

[MChampion]

I was draining my water heater this weekend to flush/fill and replace the elements, and had the cold water valve (at the heater) turned off, yet I could hear water coming into the tank from the hot side. I thought maybe it was draining back in from the pipes in the house (two story).

After a while I decided to turn off the main to the house and then the hot side stop draining into the tank.

Any thoughts on why water would be draining back in on the hot side, but only if the main to the house is open?

I can't remember specifically at the moment, but I might of had a hot water faucet open the whole time. If that would have any influence on anything.

Thanks.

 

[Reach4]

One of your fixtures has a crossover. Close stop valves to eliminate suspects.

 

[Sponsor]

 

[MChampion]

Thanks for the reply. I figured it had to be crossing over somewhere, but wasn't really thinking about the fixtures. I was thinking maybe the washing machine, but forgot about the single handle shower and kitchen sink fixtures.

I still need to replace the anode rod, so I'll drain a few gallons off and then see if I can track down the culprit while it's running back in on the hot side.

 

[hj]

It is NEVER the washing machine.

 

[Vtxrider]

I stumbled across this old post. I just went the same thing today. My basic problem is luke warm water just to shower. I've done everything to try to solve this. New Symmons valve, new PEX lines (old copper was leaking anyway), back flush and front flush. Compressed air and water. Would a valve crossing over send cold into the hot line? All other 3 sinks are fine. When I shut the off the cold feed, I get little bit of water from hot. The washer is on the same run as tub. Shower is above washer one floor up. I'm not to familiar with the cross over thing.

 

[Terry]

The Symmons valve has a temperature limit stop. Is that adjusted where you want it?

 

[Vtxrider]

The Symmons valve has a temperature limit stop. Is that adjusted where you want it?

Thanks for the reply. I've done everything regarding the whole valve including talking to Symmons on why I have lukewarm water. I posted on this because it sounded like my problem now. After trying to blow out line again with compressed air I went to refill my tank. I had drained it down to remove the hot out off of the tank to see if anything came out. It's a corrugated flex. I blew air into the Symmons valve body and through the lines. Anyway after reconnecting and opening the main valve it started filling. I never got to open the cold water valve yet. Tank filled. Got hot water to everywhere but the shower. Lukewarm. I'm going shut off every cold valve. One single, two handle and the washer valve. Single. Then try it. I might add this is not a new installation. Same piping for 43 years other then the PEX replacement and new tank. Problem existed before new tank.

 

[Jadnashua]

Any single handle faucet could be the culprit. Some people leave the shower valve on and use a shutoff at the shower head, that leaves a cross-over. Some put a Y on the hot/cold to the WM, that's a cross-over. If it isn't the limit adjustment on the shower valve itself, or possibly a partially stuck pressure balance spool valve if that's a separate part from the cartridge, or a partially blocked line to the shower, then it's a cross-over someplace.

 

[Master Plumber Mark]

All single handle pressure balanced faucets will pass over from the cold to hot side when the heater is
off and you are trying to drain it or work on it

 

[Vtxrider]

All single handle pressure balanced faucets will pass over from the cold to hot side when the heater is
off and you are trying to drain it or work on it

Well basically just trying to get hot water, getting warm water to shower. Not sure why it did the hot side feeling but it never did it again. I actually don't have single faucet. Made a mistake saying that. Besides rebuilding the valve a few times, running air through the lines front flushed and recent tank change today I back flush the hot line. Ran 50 gallons. Water was clear. I had good pressure coming out. I'm on well. Put everything back together and no difference. The line going into valve is hot but when mixed it's lukewarm out of spout. I took a temp of the hot pipe going into the valve using a infrared. It's the same temp as my other hot lines going into the sink valve.
So with that said what else? The temp screw is backed all the way out also. Handle turns well past 360. Is it the valve itself? I have one coming. I'd like to avoid changing.