Hayward Cartridge Filter - Jackhammering

[Azeric]

I posted this in the "pool cleaner" section under an old old thread but it may not get the attention it deserves.

This is a recent problem, everything was working great, no major changes made to the system.

Currently, I can have my jandy set almost all the way (full) on the VAC setting and I have normal 8PSI on pressure gauge, full strainer of water/no air bubbles but then I turn it counter clockwise another inch or so and I have air in my strainer housing, the pump starts pulsating rapidly like a jackhammer and my pressure drops to 2PSI.

Impeller spins freely when checking after pump is off, no feel of debris in there, air bled out top of filter housing. Navigator cleaner still scoots along the bottom at a decent rate. Not sure what the issue could be as this is a new home, new pool to me, the house was not maintained very well..

Other info - hayward cartridge filter, 1hp pump, hayward navigation vacuum, also located in Phoenix, AZ as some of the other threads I have read with this similar situation, coincidence?

 

[mas985]

What is the valve switching between? It is the other port that has a problem. If it is a skimmer, then it could be a stuck weir or low water or a cracked pipe.

 

[pooldv]

How long are you letting it run? Mine does that sometimes but clears up after a minute or two.

 

[Azeric]

It's a 3 way jandy that has skimmer-vac to pump so I assume it is the suction from the pool. The skimmer side 100% open is fine and the vac side open about 90% is fine but just that extra inch of a turn the pressure drops and it's like it's sucking massive amounts of air. Line is not clogged and I can leave it like that for awhile but it does not seem to "clear out". water level is good weir is not stuck, no leaks above ground, took apart valve and it is good. Impeller is not jammed and spins easily. Still stumped :/

 

[mas985]

So are you saying that you are sucking air when the vac side is closer to 100% and the skimmer is closer to 0%? That can easily happen because the vac line has so much restriction that it causes a high vacuum in the pump basket which can in turn draw in air. Normally, you shouldn't need to redirect so much flow to the vacuum unless there is a blockage in the vacuum line or head.