Hot Water From Cold

[Massey16]

We got out camping for the first time this year this past weekend. As such, I ran water through the camper to push out the antifreeze I put in last fall. Then, I switched the valves to fill the hot water heater. After it was full and heated, I noticed a leak from the plug that I couldn't fix by tightening. So, I isolated the hot water tank without turning off the external supply, fixed the leaking plug with plumber's tape, and turned the water back on to the hot water tank. Afterwards, I have noticed that when we turn the cold water on at the sink in the kitchen, we get cold initially, then extremely hot water for a short period, followed by cold. Why am I getting hot water out of the cold? Have I damaged something?

[Old-Biscuit]

That is a long line from water heater to kitchen faucet so I don't think your problem is hot/cold mixing at water heater

I think your problem is within the kitchen faucet itself. The hot/cold are not staying separated inside the faucet.


I have the same type valves on my water heater......except I have three and no check valve. And I have no issues with hot/cold mixing at water heater.

Full turn valves vs quarter turn. Can't tell by looking where open or closed.

[Nvr2loud]

Massey16 wrote:
These seem to be more similar to one's I have seen in bathrooms to turn water on/off to the tank on the toilet. Takes several turns to go from open to closed.

Very interesting.

[Massey16]

These seem to be more similar to one's I have seen in bathrooms to turn water on/off to the tank on the toilet. Takes several turns to go from open to closed.

[Nvr2loud]

Massey16 wrote:
Ah, I see what you're saying. They look like quarter turn ball valves where the handles turn in line with flow. Just a coincidence that they ended in those positions.

Any other possible explanations? Doesn't hurt anything as long as you know it will do it. Any problems when I go to winterize?

Mine are quarter turn and they look identical to yours, I even have the identical attwood heater.

[Massey16]

Ah, I see what you're saying. They look like quarter turn ball valves where the handles turn in line with flow. Just a coincidence that they ended in those positions.

Any other possible explanations? Doesn't hurt anything as long as you know it will do it. Any problems when I go to winterize?

[Nvr2loud]

Massey16 wrote:
The valve for cold into the hot water tank is open and the valve between cold water in and hot water out is closed. This would be reversed for winterizing.

Sorry the picture makes them appear completely different.

The top valve (bypass) appears OPEN in your picture

The bottom valve (cold supply) appears CLOSED in your picture.

[mhardin]

Massey16 wrote:
The valve for cold into the hot water tank is open and the valve between cold water in and hot water out is closed. This would be reversed for winterizing.

Your valves may be different than mine. Mine only turn a quarter turn and the handle is perpendicular to the pipe when closed and parallel to the pipe when open.

[Massey16]

The valve for cold into the hot water tank is open and the valve between cold water in and hot water out is closed. This would be reversed for winterizing.

[mhardin]

Your bypass valve between cold water in and hot water out is open. Closing it should solve your problem.

[Massey16]

Alright, I managed to get a few pics last night. Here is a view of the outside where the hose attaches:



This is the plug I serviced:



Here you can see the tap for the cold side of the kitchen sink above:



This is the bypass loop for the hot water heater:



Right now, the bottom valve is open and the top valve is closed. In the winter, those positions are reversed. Not sure why I am getting the hot to back up into the cold line between the inlet to the hot water heater and the faucet in the kitchen sink. I'm assuming that one white things on the hot water tank is a check valve that would keep the antifreeze out. Not sure if this is an actual problem???

[Massey16]

Thank you for all of the replies!

I will have to look when I get home as far as the make of the water heater, etc.

The water inlet comes in under the sink of the kitchen of the camper. The hot water heater is adjacent to this. The plug I serviced was the drain plug on the outside of the camper.

I thought it might be from the sun as well, but the issue was repeatable in a short period of time and also in the morning.

I believe that the cold water runs into the camper and straight to the kitchen sink, but I'll take some pics tonight.

[myredracer]

The RV Doctor says this can happen in older RVs because of the way they plumbed them and the answer is to add a check valve. http://www.rvdoctor.com/2012/06/hot-water-from-cold-faucet-in-fifth.html

[bdpreece]

Do you have an outside shower faucet? If so make sure the faucet is turned off at the knobs and not just at the head.

[flash82]

I've heard this happen before. It happened in our Pup-up once or twice. The consensus was that the water line outside was heated up from the sun.

[westend]

Massey16 wrote:
Where is the check valve located? Hard to replace?

Why would it go back to cold if the check valve is bad?

Why not share what make of water heater you have and some more details of what you serviced (plug?). All RV's, water heaters, fixers are not the same.