[DamCaki]

I have a dual pump set-up. From ground up: 2-pumps (slightly off-set, never to run at same time), followed by two check valves, then the Y (all within ~24 inches). I drilled a relief hole on the primary pump (an inch above the pump, 5-6 inches below the check). Pump kicks on and runs very quite/smooth - then loud gurgling once pump shuts off. Pump is not sucking air. If I hold my finger over the relief valve, there is no noise - remove finger and load gurgling and sounds of water running down the pipe. - PLEASE HELP.

[hkstroud]

OK, bet the end of the pipe is at a level considerably lower than the highest point of the pipe (which is probably where it goes through the wall). When pump shuts off the pipe is full of water. The water flowing out the end of the pipe pulls air in through the bleeder hole and up through the vertical section of the pipe. That is what's making the gurgling noise sound. When you block the bleeder hole you stop the air getting into the pipe and stop the flow of water out of the pipe. Everything is working as it should.
To prevent the noise put AAV where the pipe goes through the wall.

[massplumber2008]

Hkstroud is BANG on here, but I don't understand this, Harold?

To prevent the noise put AAV where the pipe goes through the wall

That would be a first for me...

Please explain how an AAV helps here?

[hkstroud]

AAV at the highest point would let air in so pipe could drain without sucking in through bleeder hole. Air being pulled up through water in vertical pipe is making noise.

[DamCaki]

Thank you vey much. Update - drilled a new relief hole through the PVC fitting (1.5 inches lower) & upped my float switch an inch or two. Now when pump shuts off the relief hole is an inch under water and the noise is much less & shorter. We can easily live with it as is - from a performance standpoint, should I still add an AAV? Thanks again!

[massplumber2008]

Most sump pumps and sewage ejectors have check valves (backflow preventers) just like you have installed, so installing an AAV would not be helpful in your case DamCaki...;)

Further, in reading your post, it could be that the check valve has gone bad and is allowing water to pass by at the end of the pump cycle. In this case, you would remove the old check valve and install a new check valve. Otherwise, it sounds like you have taken care of the issue that concerned you so you should be all set!

Mark

[hkstroud]

The end of your drain pipe must be lower than the sump pump. When pump shuts off the water flowing out the end of the drain pipe is pulling air in through the bleeder hole and up through the check valve, causing the noise. An AAV valve, above the check valve, (I would put it as high as I reasonably could), would let air in as the drain pipe drains. That would eliminate air being pulled in through the bleeder hole and prevent the noise.
Only purpose of the AAV is to eliminate the noise.

[massplumber2008]

The end of your drain pipe must be lower than the sump pump

I'm not clear on that either, Harold. A sump pump discharge pipe usually goes as high as possible in the home and then goes out the sill to the outside, so I can't see how the end of the drain pipe can be lower than the sump pump?

An AAV valve, above the check valve, (I would put it as high as I reasonably could), would let air in as the drain pipe drains

Since there is a check valve in place the pipe does not drain back to the pit...that's the point of the check valve (I know you know that). The weep hole allows water to drain from the bottom of the check valve down to the weep hole...prevents "air lock".

Am I misunderstanding something??

Thanks!

[hkstroud]

OK, if pipe goes up and out and the end of pipe is higher than pump, then when pump shuts off, water in the pipe will drain back down into sump hole. Therefore a check valve is needed. A bleeder hole is need for water between the check valve and pump to drain.
However, if pipe goes up and out and then goes down hill (usually underground) to a point lower than the sump pump. When when pump shuts off, water in the pipe down hill section of pipe will flow out the pipe. It will also siphon out the water in the vertical section of pipe. No check valve is needed. If a check valve is installed, water will still flow out the pipe at the discharge end. If there is a bleeder hole, the siphoning of the water in the vertical section will pull air in and up through the check valve. Causing it to vibrate, creating the noise. If there were no bleeder hole then the siphoning action would not only pull the water out of the vertical pipe, it would also drain the sump hole until the water level dropped enough for air to be pulled in through the pump.

Its that little bit of air through the bleeder hole that is causing the check valve to vibrate.

Is my logic all wet?

The end of your drain pipe must be lower than the sump pump.

I could have worded that better. Should have said that I was willing to bet that the end of the pipe is lower than the sump pump.

[ballengerb1]

I am with a failed check valve. The weight of the water in the pipe rising out of the pit up to the sill is all draining back. Try a new valve.

[smearcase]

I think that HK meant that-- DakHaki likely has an installation where the end of the drain pipe is lower than the sump pump, and that is part of DakHaki's problem here.

and not that- all ends of drain pipes have to be (must be) lower than the sump pump for everyone everywhere, at all times.

Right HK?

[hkstroud]

Right.