Pentair ccp420 filter waste plug blew out

[Bketchum5]

Well, my wife called me in a panic saying our spa was draining. I came home and found the waste/drain plug completely blew out. The threads on the cap look fine and from what I can tell and fill with my finger the threads on the bottom tank assembly seem fine as well.

Since i I was not home I’m not sure what the pressure might have been.

So so I get home, check the clamp around the filter. Looked snug and tight as normal.

Took clamp off and noticed as loosening the t-bolt that it was stripped but clamp was still tight during the blow out.

Anyway, proceed to screw waste plug on, start pump in service mode and it blew the plug out again.

But how could the pressure and blowing out a threaded plug not gall/strip the threads?

is it time to replace tank clamp? Only four years old.

Has anyone experienced this before?

 

[Rocket J Squirrel]

You’re talking about the drain plug at the bottom of the filter? I can’t see how that has any relation to the clamp belt around the midsection.

Years ago, when I was a noob using a pool service, they told me their policy was never to remove the drain plug when cleaning the cartridges. They said the filter body was subject to deformation if the plug was replaced too tight, and to leaks if not tight enough. So I got in the habit of draining that last bit of dirty water with my shop vac & leaving the plug alone.

So even though both sets of threads look OK, a bit of deformation may have ruined the seal. With the plug out, examine the hole for signs of deformation. You may need a new filter bottom. If you’re lucky, maybe only a replacement plug.

 

[Bketchum5]

Well, replaced the plug and no issues yet. New plug is holding.

Examined internal Val threads of the bottom filter tank and noticed pieces of black thread in the grooves. Tells me the cap plug was falling as I probably overtightened through the years. Probably just worked it’s way out on its final death bed.

We shall see if the new plug holds.