Check valve causing repetitive thumping?

[Option]

Hello,

I've scowered the internet looking for a solution and have come up empty handed. Hopefully one of you fine people will be able to help me out. Any suggestions/ideas would be greatly appreciated!

I have a small sump/pump on the side of my house which collects waste water from my downstairs bathroom (shower, sink and toilet) and pumps it up-hill to the sewer line (at least I hope that's where it's going!). The piping runs horizontally for a few inches once it clears the sump and then has a check valve (at least that's what I assume it is) that looks like the following:

Then, a few more inches up the piping there is a second check valve that looks like this:

I know that a check valve can make a loud "thump" when the pump stops and the weight of the water slams into it, but my problem is that I get a continuous repetitive thumping that can last for several minutes at a time. The duration of the thumping is very inconsistent as it sometimes lasts a few seconds and other times it drones on and on.

Does anyone have any ideas on how to correct this problem? I'm not very experienced with pluming issues/terminology but I will try to give any additional info that would be helpful. I can also post pics of the pipe setup and video of the thumping as you can visibly see the pipe vibrating in rhythm with the sound. Again, any suggestions or ideas would be greatly appreciated. Thank you!

 

[Speedbump]

I would get rid of one of them. I would also want the check valve vertical, not horizontal.

bob...

 

[Sponsor]

 

[Option]

I would get rid of one of them. I would also want the check valve vertical, not horizontal.

bob...

Thank you Bob, I appreciate the suggestion. I was also thinking that having two check valve may be causing this issue. I'll start by replacing the PVC valve with a straight section of pipe and see what happens.

Also, can you tell me why you suggest having the check valve oriented vertically instead of horizontally?

Thanks again!

 

[SewerRatz]

The brass Check valves where always installed horizontal. Some of the manufactures even say thats the only way to install them. But as Speed Bump said remove one of the check valves. there is no need for two of them.

They also make a check valve called a "Silent Check" which looks like the plastic check valve you posted with a spring attached to the flapper. They work great at eliminating the "thump" noise you get when they close.