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?

Bad check valve maybe.More information about exactly what you have will result in the best answers. What RV?What water heater?What style bypass kit?What plug/fitting did you R&R?

Where is the check valve located? Hard to replace?Why would it go back to cold if the check valve is bad?

Massey16 wrote:Where is the check valve located? Hard to replace?Why would it go back to cold if the check valve is bad?I get a little bit of hot water when I turn on the cold, I have found that the heat from the water heater will heat water in the cold plumbing run directly beside the heater. The longer we don't run water, the hotter that section of tubing gets. It has only happened since I installed a Hott Rod electric element and had to remove a section of insulation from the water heater tank.

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.

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.

Hot Water From Cold | Good Sam Community

beemerphile1
Explorer
Aug 18, 2014
Bad check valve maybe.

More information about exactly what you have will result in the best answers.

What RV?
What water heater?
What style bypass kit?
What plug/fitting did you R&R?
Massey16
Explorer
Aug 18, 2014
Where is the check valve located? Hard to replace?

Why would it go back to cold if the check valve is bad?
Nvr2loud
Explorer II
Aug 18, 2014
Massey16 wrote:
Where is the check valve located? Hard to replace?

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

I get a little bit of hot water when I turn on the cold, I have found that the heat from the water heater will heat water in the cold plumbing run directly beside the heater. The longer we don't run water, the hotter that section of tubing gets. It has only happened since I installed a Hott Rod electric element and had to remove a section of insulation from the water heater tank.
westend
Explorer
Aug 18, 2014
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.
flash82
Explorer
Aug 18, 2014
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.
bdpreece
Explorer II
Aug 18, 2014
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.
myredracer
Explorer II
Aug 18, 2014
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
Massey16
Explorer
Aug 18, 2014
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.
Massey16
Explorer
Aug 19, 2014
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???
mhardin
Explorer
Aug 19, 2014
Your bypass valve between cold water in and hot water out is open. Closing it should solve your problem.

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