Check valve between FW tank and city water?

[Alpenliter]

I've drained my fresh water tank completely, yet after a few days I end up with more water in the tank while hooked up to the pedestal. Is there a check valve allowing water to seep into the FW tank from the city water hookup? Where would I even begin to look? Thanks in advance for any suggestions.

[pewterman20]

Right on Old Biscuit. Thanks. I installed a 1/2 inch check valve on the suction side of the pump and problem solved. I didn't try to clear the pumps internal check valve...Cost about $6 for the check valve and a couple of connectors. Thanks again

[Old-Biscuit]

pewterman20 wrote:
Sorry about not getting my question in the last post. Does installing an n-line check valve also eliminate the cycling problem I'm having with the pump when I turn the water off?

Water pump cycling when there is no demand (no faucets/no leaks) is another sign of pump check valve leaking.

Installing the in-line check valve in SUCTION line of water pump will stop water from flowing backwards thru pump, overfilling fresh water tank when on city water AND stop pump cycling due to a leaky pump internal check valve.

(installing it in discharge will only stop filling of tank......pump will still continue to cycle because pressure inside pump will decrease due to leaky check valve which will cause pump pressure switch to close so pump will go burrp (short run) to make pressure switch open. This can causse damage to motor)

[brulaz]

This happened to me with a ShurFLo 4008.
It has a by-pass valve built-in that went bad.
Was sent a replacement pump under warranty.

[pewterman20]

Sorry about not getting my question in the last post. Does installing an n-line check valve also eliminate the cycling problem I'm having with the pump when I turn the water off?

[pewterman20]

Old-Biscuit wrote:
On board pump discharge and city water inlet line are tied together (same cold water line)

So there are 2 check valves in system
1 is part of the city water connection assembly so when pump is ON water doesn't come out city water connection (running down side of rig and causing pump to cycle
1 is part of pump assembly so when connected to city water backflow thru pump doesn't occur (overfilling fresh water tank)

Sometimes just running water pump will clear debris from check valve
Sometimes disassembling pump and washing check valve/diaphragms will resolve issue
Installing a 1/2" in-line check valve in pump suction line also works ($10)


Then of course there is those that have 'water panels' in wet bay where you can fill fresh water tank via a 'fill' valve when connected to city water (vs usig a gravity fill port).
Fill valve could be problem.......not closing/leaking

[BarneyS]

Moved to Tech Issues forum from DIY.

[Alpenliter]

Itchey Feet wrote:
Do you have a valve that you can turn to fill the FW tank from the city hook up or do you fill it from another method??? I found that while hooked to city water my valve leaked water into the FW tank and actually would overfill the tank to the extent that it would come out the overflow line, so all my problem was in the valve between the city water and the FW tank.

I have two separate entry ports; one for fresh water tank, the other for city water. I'm going to pull the pump and see if the check valves are in good shape.

[Itchey_Feet]

Do you have a valve that you can turn to fill the FW tank from the city hook up or do you fill it from another method??? I found that while hooked to city water my valve leaked water into the FW tank and actually would overfill the tank to the extent that it would come out the overflow line, so all my problem was in the valve between the city water and the FW tank.

[Old-Biscuit]

On board pump discharge and city water inlet line are tied together (same cold water line)

So there are 2 check valves in system
1 is part of the city water connection assembly so when pump is ON water doesn't come out city water connection (running down side of rig and causing pump to cycle
1 is part of pump assembly so when connected to city water backflow thru pump doesn't occur (overfilling fresh water tank)

Sometimes just running water pump will clear debris from check valve
Sometimes disassembling pump and washing check valve/diaphragms will resolve issue
Installing a 1/2" in-line check valve in pump suction line also works ($10)


Then of course there is those that have 'water panels' in wet bay where you can fill fresh water tank via a 'fill' valve when connected to city water (vs usig a gravity fill port).
Fill valve could be problem.......not closing/leaking

[GordonThree]

Alpenliter wrote:
I've drained my fresh water tank completely, yet after a few days I end up with more water in the tank while hooked up to the pedestal. Is there a check valve allowing water to seep into the FW tank from the city water hookup? Where would I even begin to look? Thanks in advance for any suggestions.

I have read the check valve is in the pump itself. This appears to be the case in my coach. It might be a piece of sand, rust or hard water grime is caught in the valve and it's not seating fully.