Air in check valve after pump off

[rbellavia]

Hi all

I have a raised spa with inground pool.

Noticed about 3 weeks ago
- every am spa down 3-4 inches. Pool at max level

1st TEST-
Turned autofill off, turned all equipment off and spa only down to the returns. No pool level change.

2nd test
- ran in spa mode only for 4 hrs. No water loss. Pipes on spa return side held…

I notice though that the check valve is full of air with a steady trickle stream of water at bottom with pool equipment off - happens immediately and stays like that until pump goes back on.

So I turned the equipment on- immediately primes the catch valve. Water at start up spits air out of returns in pool and spa. Spa goes back to normal level.

When I turn the pump off I immediately see a huge bubble violently fill the check valve with the above trickle of flow in the valve and and if left off overnight lose the 3-4 inches in the spa. This happens even if I immediately in one second turn the pump on then off. Air bubble is immediate. Skimmers and pool drains are at least 50 feet away. I suspect the air is pressurized and holding the valve open causing it to fail with subsequent spa drop.

3rd test
- turn equipment off, air fills the catch valve as above. I removed the top of the catch valve, primed the catch valve and then put the top back on. Spa holds its level.

I suspect an air leak? Pressure side? Causes air pressure to enter in the check valve & leading to it failing? Anyone ever see this?

Inspected all pipes. No cracks but may be time for a shaving cream test.
Why would I have air in the pressure side without losing water?
Why would air be reaccumulating so quickly if not on suction side ( about 1-2 sec after turning off)
Outflow to spa is a bifurcated pipe with one to the spa and one the the pool
Could an old DE filter be causing this?
Could this be Below ground given no water loss?

Thank you

 

[kul]

Maybe the check valve is bad. Have you tried replacing it?

 

[rbellavia]

Thanks

That’s my plan

But for the life of me I cannot explain why I’d have pressurized air bubbling up after pump turns off on the outflow side.

The suction side including my pump has no air in it.

 

[Jimrahbe]

R,

Pretty typical of a bad or dirty spa return check valve.

I suggest that you replace the whole flapper assembly. Only use the OEM replacement, as just because the cheap ones look like they will work, does not mean they will actually work.

I doubt there is anything else wrong.. When you take flapper assembly out, check to make sure that no clue got into the seal area when the original valve was installed.

Thanks,

Jim R.

 

[wireform]

I have also seen debris somehow bypass the system and as luck would have it the cv closed on the debris causing it to embed itself just on the seal portion getting stuck there which will do what you have going on. In any case a new cv kit would be first to remedy and then see if it corrected itself.