Water hammer from my check valve
 

As the title says... I replaced my check valve with a swing type and now when I unplug the return pump I get water hammer at the valve wich makes it open and close repeatedly slowly letting water into the sump as it hammers.
Any suggestions?

To avoid hammering you want to avoid shutting off the water quickly. This could be as simple as putting a ball valve after your pump (never before!) and close it slowly before shutting off your pump. But you probably don't feel like this hassle...

You can also decrease the degree of hammering by limiting the straight pipe length before and after the valve. You can further disrupt the hammer effect by adding an elbow; this disrupts the propagation of pressure waves through water.

Yay Science!

Thanks for the advice Steve, I tried both of the solutions to no avail.
I did install a ball valve after the check valve (was going to anyway to adjust flow) and I also installed a 90 after the check valve but it did not affect it at all. The ball valve works but does not help for unexpected power outages or pump failure. Any other suggestions? Anyone? What type of check valves do others use?

Maybe a pic will help...Anything wrong with this setup?
http://i100.photobucket.com/albums/m...scaper/016.jpg

From what I've seen on these boards most people plumb without a check valve since they're prone to failure. They plan their sump configuration to handle the extra water from the overflow and piping when the pump is shut off or if there is a power failure. Again, this is what I've seen in other threads, not my experience since I'm currently running a sumpless system.

+1 Good advice.

OK I realized this a long time ago...kinda obvious, but I am not going to drain my tank, take it off the stand, pull the sump out, build another bigger sump.......

+1 ?? thanks for the help:rolleyes:

Ok, a couple things that might help here:

a) Check the orientation of your check valve. Depending on the type of check valve you have in there it it might have to be mounted horizontally (ie. swing-type check valve). I see a vertically mounted check valve, so look into that.

b) You can by non-water hammer check valves. Google it, buy it, put it in, Bob's your Uncle.

c)Failing all of that, mount the check valve horizontally and put an expansion chamber before the valve. Don't go and buy one, just make if from some PVC. Again, google has some good info on how to do this. It's an easy operation.

That's all I've got for useful tips. Soon I might have to join the "You should have just plumbed without..." group .... Just kidding!

Let us know how it goes and let's see if we can't fix this.

Thanks for the suggestions Steve!! The check valve is a swing type and says it can be used vertically but maybe that is the problem. I will try this horizontally as I am re-doing my plumbing for a new pump anyway.

Would anti-siphon holes drilled in the plumbing just below the water level line in your tank work to stop your system from completely draining into the sump in the event that your return pump stops running?

Thats all I've got to offer. I dont believe in band-aid solutions in any situation. Fix the underlying problem then you and your tank will always be much better off for it.