Pipe Slam

[WML13]

I thought I knew it all, but this one has me stumped. I have a decent zoeller submersible sump pump that moves a lot of water thru a long discharge line across both basements in a condo unit. (2" line) I had to put a check valve in this line just past where it connects to the pipe coming up from the sump pipe to prevent a lot of water from coming back into the pit. I had another check valve in the line about half way to prevent water being pumped back as far as OUR pit from the other units pump in the other basement attached. I removed that check valve on advice given me here. but it has made no difference. I DO have another check valve in a cross over I made to have an alternate drain if this line plugs up when Im out of town. I COULD remove this valve too but it would be a pain if it isnt necessary. Grandma doesnt like the noise and this pump clears out this sump every 15 minutes or so in the winter, spring and fall. When the pump stops, the water pressure slams back in the pipe. I cannot see where the pipe is hitting anything when this happens. It is suspended in its run with Steel straps. Do I need to T in a line and run it up like a vent stack to prevent this? Logic would indicate this is a bad idea, considering that the pump pressure COULD probably run water clear to the roof if the other lines were plugged.

[nomind]

Hi WML 13,
- the system sounds a little baffling ? Is it possible to post some kind of drawing that I could see ? -As it stands, the only possible causes I can imagine are the fact of water under pressure being caught between two check valves. -Or the quality and robustness of the check valves. Are they brass, spring operated, or the cheap plastic ones with a flapper valve ? :cool:

Do it Right - Do it once.

[WML13]

If my new digital camera ever gets here, I will be able to do better than a drawing. both check valves are the cheap plastic kind with the rubber flapper. If you can visualize a Zoeller sump pump. with a 2' plastic pipe coming up out of the pit, takes a right angle and goes into a check valve. From there the line takes another right angle up and goes up to about ceiling height in the basement where it takes another right angle and from there goes straight across both condo crawl spaces right under the floor. (this condo has both a basement and a crawl space in both units) The other units sump does the same thing and joints the pipe in a "Y" joint and the line continues out to the storm sewer. (my line has a T spiced into it just inside the crawl space that goes up about a foot to cross over a cold air duct return where I put in another check valve to join it to another plastic drain pipe that drains the kitchen sink. (this is in case the Main line plugs )(which it usually does at 4 am in the winter when grandma is in fla and then the security company calls me to go do something about the sump overflowing.) I havent had any of those unpleasant calls since I did that lol! But I still have the slam. I can get rid of it by removing the check valve in the sump. but I get a LOT of water back into it if I do.

[nomind]

well, I'm still baffled by the cause. If it was mine I'd fool around with the area it comes out of the pump. Try putting a brass check valve in , not much more cost, and the mass may absorb noise. Also, I wonder if it would make a difference if the pump-check valve section was flexible (eg rubber hose), or if the check valve was vertical instead of horizontal. ??? :confused:

Sometimes "Doing it Right" is hard to figure out !