Question City Water Connection Leaking Into Fresh Water Tank(?)

[osuallen]

These two issues have not been corrected yet, and I am getting desperate.

1. The fresh water tank fills slowly when the trailer is connected to city water.

2. When using only the fresh water tank, the water pump continuously cycles every few seconds.

I know there have to be some sort of check valves in the system to prevent these problems, but I don't know where they are, or what they look like.

Here are a couple of pictures of the only (somewhat) accessible plumbing components. Aside from the water pump itself, I have no idea what any of this stuff is, or if it could be the cause of my problems.

PLEASE HELP!
View attachment 25929

Second picture - middle photo -- That is an air admittance valve. It is the plumbing "vent" for the lavatory.

 

[Kevin D Pem]

If the only way to fill the fresh water tank is manually and not through a valve to switch between city and fresh water tank, the the issue could be the check valve in the water pump itself. Did you try the procedure I suggested above?

Another rant! The inlet valve in the pump must act like a check valve, but it's not! RV MANUFACTURERS use it as such, and that's why there are so many problems with RVwater systems.

You may have noticed the strainer on the input! This device is required to warranty out the pump, that is because the pump manufacturer knows what they sell!

After quite a few pump replacements, I do the following:

1) put a check valve between the tank and the pump ( standard plumbing variety)
2) when that cheesy pressure switch fails, replace with a well pressure switch.

Nothing in an RV is made for real life trouble free use. I live full-time in my RV and would rather find room for quality, rather than constantly replace garbage!

Conclusion! Yes your problem is the lack of a check valve. If you're always on grid than just keep the tank drain open till you put a check valve in!!! Or put a inline valve to separate the pump from the system when not using it.

 

[Altazi]

I found manufacturer documents for the SHURflo 4008-101-A65 water pump used in my 220RBS. One shows an exploded diagram for the pump, with descriptions. Here is the legend from that drawing.

The one thing I wanted to see was the check valve - which is indicated as 'N/S', or 'Not Shown' on the drawing. FFS. After even more searching on the Internet, I found some helpful videos. I FINALLY found what I needed to know.

The check valve is part of the water pump.

NO ONE told me this. Maybe this is just one of those things that 'everyone knows'. Well, I didn't. I tore my trailer apart looking for what I thought was a separate check valve.

I removed the water pump and disassembled it.

What a pain in the arse. THIS is the check valve.

I took it apart - both O-rings seemed smooth and clean, the valve seat appeared clean and undamaged, but it doesn't seal well. I sucked on the outlet port and could easily pull air through the valve - as it should be. I blew into the outlet port and, while I met substantial resistance, air was leaking through the valve. If I held the valve assembly so the outlet port was vertical, just putting water into the port would show a dribble of water coming out of the valve.

Is this normal? Does the pump need more pressure to cause the valve to seal against backflow?

I checked on Amazon and found repair parts for the valve. There are 18% one-star reviews, with people saying it doesn't fit older pumps (mine was build in 2017). I could order an entirely new pump for around $100, or a new upper cover for around $42, but I would like to know why my check valve is leaking when the parts all appear to be okay.

I welcome any and all comments and suggestions on this. Thanks for your help so far.

A.

 

[AbdRahim]

If you clean it all up and put it back together, you may find it works fine. This has happened to me several tomes on multiple coaches. I turn of the city eater run the pump a few times. Turn off the pump and turn on city water. All was good. It often happens when city water is turned on while the pump is on or vice versa.

 

[Altazi]

Fixed for now. I plugged the pump outlet and left out the pump. All set for camping now, as long as we have city water.

I still have to figure out what’s wrong with the pump.

 

[Kevin D Pem]

The only thing wrong with the pump is it's an RV part! I told you how to fix it permanently. All you have to do is listen and go to the hardware store!

 

[Altazi]

The only thing wrong with the pump is it's an RV part! I told you how to fix it permanently. All you have to do is listen and go to the hardware store!

I heard you.

First, I don't have time for a major re-engineering of the trailer's water system, as we are leaving on a camping trip in about 30 minutes.

Second, the pump seems to work fine except for the check valve. I want to investigate the nature of the problem, and try fixing it there first.

Thanks for the suggestions.

 

[RVThereYet]

I also had that same problem. Decided after reading about fresh water tank filling when hooked to city water, that I was done wasting my time and getting frustrated. Time was more important so I just replaced the pump. Problem solved. I also put in a little bit larger pump capacity. Better water pressure when using the pump.
Also, you should never have the pump running when connected to city water. Or so I have been told by repair tech.

 

[osuallen]

Also, you should never have the pump running when connected to city water. Or so I have been told by repair tech.

That is certainly not exactly true. I have been at campgrounds with very poor water pressure where running the pump made things much better.

 

[RVThereYet]

This is what the world go round and round. The pump has a valve that changes depending on pump pressure or city water pressure. I know you have heard of the problems with that valve getting corroded or dirty with some substance and when you are hooked to the city water, your fresh water tank over flows due to that valve being stuck. Solution that may work is to turn of the city water, turn on the pump for a little then turn the city water back on. That tends to reset the valve.
In the future if your fresh water tank over flows, you will know why. I have read on numerous sites that if the city water pressure is low, they fill the fresh take and use just the pump. I have never heard that it is recommended to use the pump to augment your city water pressure but it's your RV you can most certainly do what you wish to do. I for one, will not being doing that method.
Happy Glamping!!

 

[BGott]

I had the same problem with my 2019 Wolf Pup 16FQ. I seemed to have cured it accidentally by flushing out the fresh water tank with bleach. The camper had set for years with a full tank and had a bunch of nasty Zooglia looking stuff plugging the fittings. When I flushed all the crap out of the system the bleeding over from the city water to the tank and the pump screwing up went away, too.