Replacement of check valve flapper

[tstex]

Hello to all,

Need to replace the ckeck valve flapper that separates the back flow from the puck dispenser to the heater. I only use pucks when needing to increase my CYA.

The first pic is the ck valve, the second pic is an overall pic w Ck valve just right of the heater and left of the filter.

My question is what do I need to drain so when opening up the valve, I'm not spilling water everywhere? I would assume opening the air relief valve on the filter, is there anything else recommended?

Thank you
tstex

 

[tstex]

Any thoughts?

Also, when replacing the flapper, I know to silicone the O-ring, but is it recommended to put silicone on the flapper edges?

Thanks, tstex

 

[Rossterman]

I would although it will likely wash away after awhile.

 

[avspin]

Looks like closing the valves to isolate the check valve are after it and the one before the filter. You will spill water but only what's in the line.
I use Magic Lube on the o-rings, not too much. I don't know about lubing the check valve.