Pressure in Line? Bad check valve?

Hello all,

I recently moved into a house where I have a sink in my basement which sits below the main pipe out to the sewer so I have a pump attached to the sink in order to push the water out. I have a ball valve for shutting off the line and a spring type check valve to prevent water from coming back up into the sink.

I have attached a crude diagram of the setup.

I'm running into a scenario where water travels back down the pipe and into the pump, which causes the pump to short cycle. I would think that the check valve (it is oriented correctly) should stop this from happening but it doesn't seem to be.

I thought the check valve might have been bad (it was positioned horizontally originally) so I replaced it and that seemed to work for a while but eventually the same thing started happening again. I was able to fix the issue temporarily by turning the pump off, filling the sink with water and then turning the pump on, letting it push all the water out but it only lasted for a couple weeks.

Leaving the pump off, water will end up coming back into the sink. Turning the ball valve seems to be the only way to keep water out for now.

I had a plumber look at it a while back but he said he wasn't sure what was happening and said that maybe there was some negative pressure in the stack that was causing the check valve to open up.

Any suggestions or ideas would be appreciated!

The check valve should be closer to pump.

You said you "replaced it". Or did you relocate the existing one.
If you didn't actually replace it with a new one, that would be the way to go.

Size and manufacturer of the existing check valve?

Diehard said:

You said you "replaced it". Or did you relocate the existing one.
If you didn't actually replace it with a new one, that would be the way to go.

Size and manufacturer of the existing check valve?

Click to expand...

When I moved in, the original configuration had a backwards pitched horizontal pipe and similar check valve in the horizontal position right before the connection to the main stack. I was having this problem then too so I thought replacing the fittings and correcting the pitch would be the best way to fix it. I installed the new check valve in the vertical with the thought that it may be better being closer to the pump and working with gravity and re-pitched the horizontal pipe.

The issue went away completely for a couple months but just started happening again.

The valve is from Lowes and its 2.5" if I remember correctly.

I have never heard of using a spring check for waste water. Try replacing it with a swing style check valve

SHEPLMBR said:

I have never heard of using a spring check for waste water. Try replacing it with a swing style check valve

Click to expand...

Is there a particular place in the line the valve should be?

the ck valve should be located outside of the sump pit
swing check is the normal ck used for sewage

there are 2 different types of check valves
their is a spring check that can be installed in the vertical and horizontal position
and
a swing check that can only be installed in the horizontal position
swing check needs to be level

frodo said:

the ck valve should be located outside of the sump pit

there are 2 different types of check valves
their is a spring check that can be installed in the vertical and horizontal position
and
a swing check that can only be installed in the horizontal position
swing check needs to be level

View attachment 19117

Click to expand...

Understood. All in all, is there really a significant difference in the two valves and where they are placed (swing horizontally vs spring vertically)? I understand how they both work but I think ultimately the question is, how is water still getting past the spring valve? I could take johnhj20's advice and place a valve much closer to the pump vs installing swing check horizontally where you indicate and am trying to understand which method would be more effective.

Like I mentioned originally, I've replaced this valve before and that valve was working when I took it out. I'm assuming that the valve in their now is also working but something else is a play here that I'm unable to figure out.

Thanks

I am not sure I am seeing this correctly. Since I cannot read the words on your drawing.

Regardless, the water that is in the pipe between the pump and the check valve will always run back into the pump reservoir. If the check valve is far enough away from the pump, the amount of water flowing back could be enough to make the pump turn on. If the check valve were closer to the pump, only a small amount of water would backtrack.

the explanation is very simple

they sell spring check valves at lowes and ho depot that can be used in your pump ed line from your sink
these check valves are plastic spring check valves also referred to as a wafer valve
they stop the water from coming back down the line to your pit
there by having the pit fill with back washed water from the pipe.

see jeffmattero76 comment above this one

if you have determined that your placement of the ck valve is not allowing the residual water to fall back to the pump
then the next step is to examine the check valve itself
it works by a spring pressing a rubber disc against an oring
this is most likely the problem spot
trash/hair/spit/toothpaste/ whatever. has gotten in between the disc and the o ring
THIS [maintaince] is the very reason I never use spring checks on a sewage/sump line

A swing check is less apt to be affected by liquids containing solids. And should be installed in a horizontal line to prevent materials from collecting on the top of the disc.

frodo said:

the ck valve should be located outside of the sump pit
swing check is the normal ck used for sewage

there are 2 different types of check valves
their is a spring check that can be installed in the vertical and horizontal position
and
a swing check that can only be installed in the horizontal position
swing check needs to be level

View attachment 19117

Click to expand...

swings can be installed on the vertical. PVC check valves, compression type. Done that way here all day long.

No question about swing checks being okay in vertical installations, when not subject to solids, which can collect on the top of the disc.

Thanks for all the replies. This is a utility/washing machine drain sink so there are no solids being pumped through this line.

I understand that there could be water between the check and the pump but to go several months without any back flow issues only to have them again seems odd. Otherwise, if water was stuck between the two, the pump would be running constantly trying to push the water out, which it is not doing.

Water is trickling back down through the pipe, fills the pump and the pump cycles pushing it back out. If I leave it alone and on, this will happen 20 times throughout the day but it isn't continuously running.

The pump should be more than capable of pushing the water through the pipe.

frodo said:

the explanation is very simple

they sell spring check valves at lowes and ho depot that can be used in your pump ed line from your sink
these check valves are plastic spring check valves also referred to as a wafer valve
they stop the water from coming back down the line to your pit
there by having the pit fill with back washed water from the pipe.

see jeffmattero76 comment above this one

if you have determined that your placement of the ck valve is not allowing the residual water to fall back to the pump
then the next step is to examine the check valve itself
it works by a spring pressing a rubber disc against an oring
this is most likely the problem spot
trash/hair/spit/toothpaste/ whatever. has gotten in between the disc and the o ring
THIS [maintaince] is the very reason I never use spring checks on a sewage/sump line

Click to expand...

Makes sense. What doesn't make sense is that I've already taken the check out once and it was operating fine. I'm willing to bet that this one will be working fine too, once its removed.