How to Empty Fresh Water Tank

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Mr.T
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Another Check Valve

Our fresh water tank also overflowed itself from city water.  It was slightly under a year old, suddenly there was water all over the ground in back of the trailer coming from the tank fill port.  Felt like saying there's nothing to see here, it's just fresh water folks!  Without city water, the freshwater pump ran nearly continuously with all the water faucets closed, which is the other symptom for the same problem.

I replaced the pump (new one sent under warranty).  And similar to ac0gv, I added a check valve to the pump discharge line as a backup.  The check valve I used was a SharkBite for 1/2" pex.

The check valve is the brass part in the blue pex tubing, in the center of the pic below.

I took apart the old pump and the rubber check valve was deformed.  Looked like holding constant pressure had deformed it, or maybe it wasn't resistant enough to anti-freeze.

 

catdancing0531
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Joined: 12/22/2018 - 18:59
check valve and fresh water drain cock

This sounds like a common problem! My Scamp/pump was also less than a year old when I had the check valve issue.  Still under warranty.

I discovered that the fresh water tank wouldn't work when I had city water turned on.  The repair guy told me to turn off the city water, since that had the system under pressure, then try the pump. Sure enough, that worked and I was able to drain that fresh water tank much faster.

I asked the repair guy to consider installing just a check valve vs replacing the pump (again).  He said he didn't know if there would be room, so I sent him (attached) pic.  Seems like the drain cock might also need to be replaced.  

A lot of hassle and expense for a system I don't even use!  I'm selling this 16' Scamp soon and replacing with a 13' Scamp and I've asked that this fresh water tank NOT be installed.  I could use the storage space.

Mr.T
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Regarding the freshwater pump not running...

Regarding the freshwater pump not running when connected to city water, that's perfectly normal.  There is a pressure switch built into the pump that runs it when the water pressure gets low -- The city water pressure kept the pressure high, so the pump will never start with city water connected.

Not sure how common the check valve problem is, but I did notice that Scamp now has a different brand water pump in the parts section of the web site.

A pump like this is pretty basic, and I think the manufacturer just got something wrong with the QC of some of the rubber -- Hopefully fixed by now.  A pump like this should last 10 years or more with average use, even the one in my grandparents 1970's RV had no problem doing that! wink

catdancing0531
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city water pressure, pump

Okay, I didn't know that about the city water pressure making a difference.  Glad I found out, and thanks for the insight.

Since the pump does its job pumping, I don't want the added expense of replacing it a second time just for the sake of a check valve.  This will be twice in 3 years. Seems cheaper to just add a check valve if that can be done. It's already costing me plenty to have an RV repair service do the work.

 

Mr.T
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Check valve was 10 minute job...

Installing the check valve (see pic in post #8) only took 10 minutes, and 9 of those minutes was planning!  Key point, the check valve has to be added on the discharge side of the pump -- note that the filter is on the suction side.   The only tool required was a tubing cutter for plastic tubing.  Hopefully an RV shop wouldn't charge much labor for that, especially for a regular customer.

catdancing0531
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mobile RV repair service

An RV repair service, when they come to you at your RV site, charge about $100 just to show up, then another $100 for the first hour of labor.  It's ridiculous, I know.  But I've found this to be typical in most places I've been.  I probably also want them to replace the "$3.00" petcock drain valve.  It might be just a simple job, but then again if something unforeseen is a problem, well that's what I'm paying them for. 

Paul O.
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As posted above, the city

As posted above, the city water pressure is usually high enough so that the fresh water pump will not run when turned on, the pressure switch keeping it off. I have a "city water" pressure reducer that lets through only about 25 psi, and when somebody turns on the fresh water pump, it does run and pumps water into the system (from the fresh water tank) until its own pressure sensor turns it off.

-Paul
2004 Scamp 19 Deluxe,
Tacoma, Double Cab, 6 cyl. 4WD
Colorado

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