# Help!! Shower hot, cold water problem?



## Harleyobsessed (Jun 13, 2011)

So i have a FunFinder Toy Hauler, 2 years old, this weekend while my wife was using the shower when the pump was running the water was cold and when the pump would kick off it was really hot.. First time used this year but was fine last year any ideas??? Thanks, Cowboy


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## artmart (Sep 21, 2010)

What do you mean it was hot when the pump was not running? This makes no sense. Are you connected to a water supply? This is the only way you can get any pressure and get hot water when the pump is not running. The pump can only be used when not on a connected water supply.

The only other thing I can think of is a bad or enabled bypass valve somewhere. When winterizing one can enable a bypass and forget to disable it. Otherwise if it's been disabled and it has failed it might not work correctly.

Again, I think your description is confusing unless we can get more information on how things are being connected and used. There are other possibilities but I can't get into them until you can provide more information - like water pressure and something else might be wrong.


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## Harleyobsessed (Jun 13, 2011)

Not connected to city water supply, only tank water but when the water is on the pump does kick on and off, like it runs builds up pressure and then shuts off for a few seconds while its off the pressure does drop some but still has decent enough flow to shower,only the temp doesnt stay consistent, as a matter of fact when pump is running water is very cold when it kicks off for a few seconds its scaulding hot, does this help? maybe i can hook up city water hose this weekend and see if that makes a difference..


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## artmart (Sep 21, 2010)

Are you using the showerhead shutoff when this happens? One of the biggest problems of an RV is keeping the water pressure consistent. The shutoffs are a blessing and a disguise. While they help with limiting usage, they really mess up the pressure. The only time a pump runs is when it senses that the pressure drops and the pump pressurizes the water in the plumbing so that it can be used with whatever faucet is being used.

In my rig, if I use the shutoff I must turn off the cold water valve too since the cold has better pressure than the hot. Then with the shutoff at the shower head is on, this cold water starts to back up into the hot water so when I turn the water flow back on all I get is a cold shower until the hot water finally makes it back up the line.

In my opinion a city line has better pressure control than an RV pump and we don't use the RV pump very often (we don't boondock much either). Don't forget the city water pressure regulator! These keep the water pressure into the RV at about 40 psi. You might be having a problem with your RV water pump regulating pressure, you might have some kind of blockage (like a bypass) valve in the hot water line, or you might have some other plumbing problem (boy, I bet this will help you a lot, sorry).

Another thing to try is open the relief valve at the water heater to ensure there is not a lot of air (watch out, this could be scalding hot) which can reduce pressure. Using GREAT care, open the pressure relief valve. If you hear air, that's air escaping and this can impact hot water pressure. If you see water, then it's good and you need to shut if back off.

There's some new things to know about. Thanks for the additional information. You are now approaching the extent of what I know about RV plumbing.


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## artmart (Sep 21, 2010)

I just thought of something else. Maybe the problem with the rig is that the pump is not connected to the hot water inlet, too. It is supposed to feed both the cold water to the rig and the cold water to the water heater so that both are equalized. This might be where there is a bypass. The bypass is there because some people winterize the rig and you don't want the winterizing fluid in the hot water heater.

Did you or someone else winterize the rig? Did you store your rig with water still in it? These might reveal other things to look for or try.


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## Harleyobsessed (Jun 13, 2011)

Had it winterized at dealer makes since then that i need to re-check all the bypass switches i know i opened 2 maybe i missed one Thanks so much friend, were new to this all, but love our Toy-hauler for taking Harley to bike rally's..


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## Allstarspoodles (Jul 4, 2011)

*Water Issue in Shower*

We recently purchased a used motorhome and are experiencing the same problem. No pressure in the shower but good pressure in the sinks. Shower is scalding then ice cold. This is by using the water tank and pump system as this is the only we have at this time. 
The RV was winterized last winter.

Welcome any help with this problem.:shrug:


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## artmart (Sep 21, 2010)

Who winterized it? This sounds like a similar problem from the OP. When water temps fluctuate like this it's typically a water pressure problem exacerbated by changing water pressure like a pump. Maybe the hot water bypass is still engaged and/or not very good so that it allows some hot water through sometimes. There can also be (defective) backflow preventers in line somewhere. Since there are numerous ways each manufacturer puts thing together and a lot of work to find the issue, put your Sherlock Holmes hat on and start tracing things back to find the possibilities.

RV plumbing is not the same as House plumbing in all cases and don't be surprised when you find a "what the heck is that?", or "why the heck is that"?, or "what the heck were they thinking?" moment. Owning an RV has been a learning experience on what's possible and I don't think it will ever end.


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