Air leak at sand filter

[joel0711]

Hayward sand filter s244t






running great with power on. When power off I have an air leak some where,,no water leakage when running. Checked drain plug,pressure gauge,,small glass observation jar,no water coming from any of them. I'm thinking the gasket at top of multiport valve may be letting air in when off and have ordered a new gasket.I can hear/feel water/air going thru return pipe with power off, I replaced multiport valve 2 years ago but believe it was unnecessary at that time. Am I on the right track to stopping air leak,don't want to loose prime while I'm away!!

 

[Texas Splash]

Sounds like a tricky one. I don't recall ... does your Hayward have an air bleed outside? Some sand filters have an O-ring between the air bleed tube inside and the relief valve that can develop a very small leak. Not enough to visually show a leak on the outside, but enough to let air in when turned off. Figured I'd mention it in case you do have one and/or the spider gasket doesn't work out.

 

[sktn77a]

Intersting. I have the same issue with the same filter. No leaks on the pressure side when the pump is on and no bubbles from the suction side but when the pump stops, there's a gurgling from the MPV and water flows back through the pump and back into the pool via the suction lines. The MPV is a Hayward SP0714T and I figure that the seal/diverter is sealing under pressure but leaking when there's no pressure on it. There are some other issues with the valve so I have a new one ready to go in when the weather improved.

 

[Texas Splash]

Might also be worth noting the spring in the MPV handle. Perhaps if worn, might not be pressing hard enough against the gasket to create a good seal?

 

[Pool_Medic]

I suspect it’s coming from either your sight glass or your gauge. Retape them both.

 

[JohnT]

My bet is it has nothing to do with your filter. It's not at all uncommon for a suction side leak to seal while the pump is running, then vent when the pump shuts off and allow the water to drain out of the plumbing. The strainer basket lid is a common source of such leaks. On a properly sealed system, you often hear water draining out of the return side plumbing when you break the seal on the strainer basket lid. My Liquidator flow meter was a source of air leaking on my setup and I eventually just removed it after several attempts to seal it.