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Water supply to shower

1999 U295.  On our last 2 outings we have had a problem with controlling the water temperature in the shower.  After you get the temperature adjusted to your liking everything is fine until the pump turns on.  When the pump is running you get colder water.  When the pump stops running the temperature returns to where you had it adjusted.  I'm thinking there is a restriction between the water pump and the water heater.

We have had the coach for 3 years and didn't have any problems until recently.  I had drained the tanks and filled with fresh water before we took the MH out for a weekend.  I use a good quality whole house filter in the supply line so I don't think I introduced any foreign material into the system.  I didn't do anything diffrent than I normally do when draining and sanitizing the water system.

Any suggestions would be appreciated.
Larry & Karen Pontius
2007 Nimbus

Re: Water supply to shower

Reply #1 –
DO you have an aquahot. It sounds like a mixing valve issue.
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Water supply to shower

Reply #2 –
No, we do not have Aqua Hot.  It is a 10 gallon gas/electric water heater. Water pump with accumulator tank
Larry & Karen Pontius
2007 Nimbus

Re: Water supply to shower

Reply #3 –
How do you run water when pump stops? Are you connected to city water and also leave your water pump on? How is the shower with only city water or only water pump?

Re: Water supply to shower

Reply #4 –
We were dry camping so we were using water from the fresh water holding tank and the water pump the last two outings. When the pump stops we are using the pressure form the accumulator/bladder tank. 

Most of our State parks in Indiana have electric but no water at the camp sites. 
Larry & Karen Pontius
2007 Nimbus

Re: Water supply to shower

Reply #5 –
The clue to why you have varying shower water temp is changing water pressure that happens with pump/accumulator cycles.. Most shower faucets try to prevent scalding with automatic temperature controls built in. But they take the easy (cheaper) way out and vary the amount of cold or hot water based upon pressure changes, rather than actual water temperature change.

Moen has a lifetime guarantee to original owner. They have no way of knowing who is original owner. If you have a Moen faucet, you may be able to get replacement guts which may clear things up.

Lime deposits from hot water tank can clog things up, so we flush out our hot water tank every few months. Be sure to turn any electric hot water tank heating element off before draining tank. RV stores have a slim wand that goes on the end of water hose to help flush out deposits, which can solidify.

The newer Shurflo water pump model 4008 has a built-in mechanical bypass to help reduce slow water flow pump cycling and it does not need an accumulator, which in itself can be a source of water contamination. Getting rid of accumulator may also help your shower temp changes

Re: Water supply to shower

Reply #6 –
We have a shower head with a small shut off on it. So I can turn the pump on to the mix of cold and hot I want, lather up and shut of the water at the head. But it doesn't shut the water off entirely. So when I rinse I have water at my temp when I turn the head valve on.

best, paul
Quote
1999 U295.  On our last 2 outings we have had a problem with controlling the water temperature in the shower. After you get the temperature adjusted to your liking everything is fine until the pump turns on. When the pump is running you get colder water. When the pump stops running the temperature returns to where you had it adjusted. I'm thinking there is a restriction between the water pump and the water heater.

We have had the coach for 3 years and didn't have any problems until recently. I had drained the tanks and filled with fresh water before we took the MH out for a weekend. I use a good quality whole house filter in the supply line so I don't think I introduced any foreign material into the system. I didn't do anything diffrent than I normally do when draining and sanitizing the water system.

Any suggestions would be appreciated.

Larry Pontius
1999 U295 36'
1999 U320 40' 1200 watts on roof. 12cf AC/DC Cold plate fridge/freezer. VMS 240 CL Honda Element

Re: Water supply to shower

Reply #7 –

Our shower does the same thing when we're running on internal water.  I think cold and hot water paths to the shower have different flow restriction, so when the pump pressure changes, the mix changes too.  Guessing that the hot water flow path has more restriction, you could try tweaking the cold water flow to just the shower at the Manobloc.

I assumed our Moen shower valve was the pressure compensating type and was stuck with calcium deposits, but when I opened up the back (through the cabinet in the bedroom), found that it was not a pressure balancing model, so I've just ordered a Moen "Moentrol" pressure balancing valve from Amazon
( Amazon.com: Moen 3570 M-PACT Moentrol 1/2-Inch CC Valve with Stops: Home ), and will add the appropriate fittings, modify the existing trim piece, and replace the current valve.  That should fix both the temp change from pump cycling and also eliminate the loud cries from the shower when kitchen water is used at an inopportune time...

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Dave and Nancy
1999/2013 U270 36' Xtreme
Motorcade # 16774
2013 Subaru Outback
KD0NIM

Re: Water supply to shower

Reply #8 –
Dave, thanks for the information on the new valve.  Our shower valve is not temperature or pressure compensating.  I would be interested is getting your opinion on how the new valve works after you have a chance to try it out.  I still have a few things I want to try, like I stated earlier everything worked fine until a couple weeks ago.
Larry & Karen Pontius
2007 Nimbus