Shower Temp Goes Cold

[gepaine]

My problem with RV shower heads is the following scenario which has always occured in both TT's we have owned:

1. Turn push button to "ON" position.
2. Turn hot and cold water valves on and adjust to desired temp.
3. Start Navy shower.
4. Turn push button to "OFF" position.
5. Continue Navy shower.
6. Turn push button to "ON" position AND get freezing cold water blast instead of water that is the temp we previously adjusted it to. (The water returns to desired setting after about 5 seconds.)

So, what's the deal? Is this normal? Does anyone else have this experience?

[Outbackmel]

I have a 2011 Outback Sydney with the factory installed shower head. Do have a similar issue. When I switch from off to on; I do need to wait a few seconds for the water to adjust to the previous setting. Ours is a hand held shower head so it is easy to avoid any immediate "surprise" cold bursts.

If you need to stand under the head at all times; I can understand why this would be not very pleasant.

I figure this is SOP for such a small system. I also would like to hear about experiences and solutions if any exist.

[hankpage]

Originally Posted by gepaine

So, what's the deal? Is this normal? Does anyone else have this experience?

Yes it is normal. I am told that somehow the water recirculates through the shower valve when shut off at the head. I found this out when my outside shower was off at the head only and gave me problems at all faucets. Some folks claim they have solved it by changing shower heads but I had no luck. It is a heck of a way to wake yourself up in the morning,

Some home shower valves will do the same depending on how the pressure balancer is designed. (Anti- Scald feature)

[DocData757]

This is very normal. Running the water for 5 seconds to get the temperature back is still a lot more conservative than running the water all the time (also know to sailors as a 'Hollywood').

I ran into just the opposite problem on the aircraft carrier I was on. The showers up on the 03 level had hand held shower heads with a spring loaded shutoff valve. Once you got the water temp set, wet down, put the shower head down and soaped up, the HOT water would back up in the cold water line and it took a lot longer than 5 seconds to get the water back to normal... more like 5 minutes. Usually ended up boiling myself in quick rinses to get the soap off. What a joy!

[geo]

Basically it's a physics thing. Water cutoff is on the showerhead, so hot and cold water are in confluence at the valves. The hot water starts to cool when you hit the button, cold water starts invading the hot water Pex, thus accelerating the cooling process. When you turn the water back on, both feeds output cold water, then you have to warm the Pex and valves again, and then you finally have shower water. Outside of the "grin and bare it" or allowing the water to run, the fix might or might not be easy.

One can get a "one-way" Pex fitting (a back-flow preventer that doesn't vent water). This fitting needs to be installed very close to the hot water valve (faucet) in the shower. Depending upon how close you can get to the valve, you will prevent the less dense hot water from "shrinking" and the cold water encroachment.

Now, Dave's problem was probably that the aircraft carrier's hot water was tapped off the ship's boilers, so it was under greater pressure than the pump driven cold water. If some pipefitter had put a correct pressure regulator in the mix, Dave, you could have had a very long Hollywood shower! Or a balanced Navy shower.

Hank, your outside shower was probably close enough to the hot water tank that when you turned it off at the shower head, you basically "short circuited" the hot water by pulling water through the outside shower valve assembly. Shorter distance and less pressure drop than running through the hot water tank.
Ron

[hankaye]

Howdy All;

Navy showers are Navy showers......

I've had Jet fuel, from hot and cold, cold from hot, hot from cold, waste from either or both.....all depended on who was mad at who, weither the "Water King" got a goodie package from Momma any number of things.

Read this article awhile back, makes sense to me...

http://rvnow.rvtravel.com/2008/05/fr...wer.html#links

How to beat the "Water King" at his own game...


hankaye

[jq1031]

Normal it is!!

[ktmracer]

this is a common problem and fortunetly has a very easy solution. Problem is that mfg today are installing a hot water bypass system with a single 1/4 turn valve. to make it work, there is a backflow valve on the hot water tank on the hot water out. However, the backflow valve restriction is very flow dependent so when you lower the flow, the hot water flow is reduced more than the cold water flow. hence the burst of cold water.

One solution is to get a water bypass kit that has TWO valves to divert water around the tank and toss the backflow valve on the tank in the garbage. Now hot and cold water flow rates track and problem gone. My dealers parts dept. sells lots of these kits just for this problem. This will solve the problem on all the faucets in the trailer.

Once we did this mod, all the faucets water temp is basically independent of flow rate.

[hankaye]

ktmracer, Howdy;

I've heard of that also, wouldn't happen to have a photo or 2 for show-n-tell
would ya ???

Some of us (me ), work better from pictures ...

Thanks,

hankaye

Think the setup in my older TT (1995), had 3 valves (Cold, Hot, & by-pass pipe)

[gkainz]

I've had many a Navy shower (until I cruised on the Nimitz - nuke power = more fresh water)... but our Laredo holds the temp quite nicely with the shower head in the OFF position.