What is this flap/gate for?

[pb4uswim]

This small basket (sorry, I don’t know the correct term) is right before my SWG and right after the heater. The cover has a flap that I’m trying to figure out. The first time I took the cap off, the flap was perpendicular to the water flow, basically doing nothing. That’s the way it was originally installed by the pool builder. Seeing it was a flap, I turned it 90 degrees so that it would function “properly”. In my mind, if there’s a flap, it should close when the water is not moving and open when it is. The thing is, now with a little more understanding of my system, I don’t see any purpose for having the flap be operational. There’s no sensor attached to it so it’s not measuring flow. And, the cap has indexes on it to turn it either way. I’m wondering if I should put it back the way it was originally installed.

 

[Jimrahbe]

pb,

It is called a check valve.. It lets water flow only one way.

When you have a tablet feeder, it keeps acidic tablets from flowing backwards into the heater.. It is not needed, because when a SWCG is off, there is nothing to flow backwards.. (Unless you also have a tablet feeder and a SWCG.)

Thanks,

Jim R.

 

[ajw22]

That is a check valve.

It is not needed when using a SWG to have it between the SWG and the heater. Although heater manufacturers require it for any "chorlinator" after the heater.

 

[pb4uswim]

Thank you.