Cold water blast in shower

[The Sod Father]

Grettings all. When taking a navy shower, I do the following -
1) Turn on water and mix to right temp
2) get wet
3) turn off water at shower head
4) lather up
5) turn on water at shower head and scream like a little girl when I get blasted by cold water.

I did some searching and found a few theories on this.

a) Since the newer trailers come with a "1 valve" water heater bypass, the check valve does not engage and allows the hot water cycles back into the tank. The solution is to install a 2 valve bypass system.

b) Same as above, but instead install a check valve on the cold water line.

Has anyone done either of these mods to resolve this issue? What was the result?

[Johnnyfry]

I have purchased the check valve but have not installed it as of yet.

My theory is that when you cut off the flow at the shower head and leave the valves open, there is an open connection between the hot and cold lines.
Since hot water is less dense than cold water, thermosiphoning occurs and the denser cold water displaces hot in the supply line and you get a shot of cold water when you turn it on again.

A check valve in the hot line should cure this.

John

[The Sod Father]

Tanks John. I did some more searching and found that this is a common issue with RV's that have a 1 valve bypass system for the water heater. Another solution is to install a 2 valve bypass. I had that type of system on my last trailer and did not have an issue.

[CincyGus]

I just remember to point the shower head at the wall before turning the water back on until it warms and then point it back at me. I warn guests sometimes, sometimes I let them discover for themselve's and chuckle when I hear the scream.

[Halibutman214]

To the best of my knowledge I don't have any sort of bypass in my Lance (or at least that I know of) and have the same issue? If you know about Navy showers then suck it up at least your whole shower isn't cold.

[The Sod Father]

Originally Posted by Halibutman214

To the best of my knowledge I don't have any sort of bypass in my Lance (or at least that I know of) and have the same issue? If you know about Navy showers then suck it up at least your whole shower isn't cold.

It's not so much me as it is the princesses I camp with. Happy wife, happy life.

BTW - I cannot imagine you NOT having a bypass on your water heater. It is used for winterizing your water system. The bypass saves you from pumping pink stuff into your water heater.

[Halibutman214]

Originally Posted by The Sod Father

It's not so much me as it is the princesses I camp with. Happy wife, happy life.

BTW - I cannot imagine you NOT having a bypass on your water heater. It is used for winterizing your water system. The bypass saves you from pumping pink stuff into your water heater.

Geez how for even a minute could I forget the princesses. I have three of my own. As for the bypass valve I do in fact have one after all. l was cleaning up the camper real good for a potential buyer and there it was right in front of me. Can't imagine how I missed it as I check the batteries often. I've always used LP air to clear the lines for winterization (and it's stored inside) and have never had a problem.