Water Draining Out of Backup Sump

[bkirby]

I just installed a Zoeller Basement Sentry backup sump. The pump has a check valve built into it and the instructions did not say to install a check valve in the discharge line. When my main pump shuts off, some water is coming out of the bottom of the backup pump. There is no water coming out of the backup pump when the main pump is running.

The the main pump sits on the bottom of the well and the backup sits on a brick about 3 inches off the bottom. They both discharge through same pipe (they come together in a Y after the check valve on the main sump) The pump is located in a garage so there is only about 2-3 feet of head at the most.

Do I need to install another check valve in the discharge pipe for the backup or do I have a defective backup pump? It doesn't appear to be a lot of water so is this normal and I shouldn't worry about it?

Thanks for your help!

[mdshunk]

There will always be some water in the pump body and the pipe from the pump up to the check valve. When the pump shuts down, this water (maybe up to 1/2 a gallon) will naturally drain back. It's completely normal.

On a side note, I seem to remember Zeoller being one of the manufacturer's who wanted you to drill a 1/8" hole in the pipe between the pump and the check. Got your instruction sheet handy?

[bkirby]

Thanks for the reply. The check valve is built into the pump. That is the only check valve on the line for the back up. The primary pump has a check valve but it is before the Y where the back up pump joins into the discharge line.

My pump is in the garage at ground level. It goes out to a french drain. I just moved into this house so I don't know how everything drains in the yard yet but my concern is that when it rains hard would it be possible for water to come into the sump pit through the discharge line? If so, I don't want it coming into the pit through the backup sump.

Does it hurt to install a second check valve on the backup?

[AllanJ]

Does the pump discharge into the French drain or does the French drain discharge into your pump pit for your pump to get rid of somewhere else?

A French drain needs a discharge of its own, either gravity to the (sloped) ground surface some distance away, or a pit (sump) and sump pump.

Your pump discharge line should not be to a location that often gets flooded itself and lets water come back into your pit.

I would not bother to install a second check valve. If the water is not pure, chances are that the check valves will be slightly ajar from particulate matter. They will still perform the important function of not letting water pumped by the main pump short circuit back to the pit through the backup pump, or vice versa.

[bkirby]

I contacted Zoeller's tech support and they determined that since there is only about a 2 foot head on the discharge, there was not enough pressure to close the check valve. When the primary pump was on, there was enough pressure so no water would come through at that time. They said that given my installation, it would hardly have any affect on the backup pump's performance to install a second check valve so that's what I did. Everything runs perfectly now.

Thanks for your help!