Big blue filter leaking slowly

[Seiyafan]

I installed a big blue filter today and I was having problem with water leaking between the housing and the sump. I also bought a spare one just in case so I tried it but it too had leak. The leak was a small stream after I hand tightened the sump, then it slowed to a drop after I tightened more with a wrench for about 1/8 of a turn. O-ring was new, right out of the box, and I didn't install any filter in the sump (only for the pressure/leak test). I am afraid if I tighten it more I may have a hard time to loosen it in the future, also the instruction says hand tight, so ideally it should not leak if I tighten it only by hand.

Any ideas? This is with two new blue filters.

 

[Reach4]

Some "big blue" filter housings are not the real Pentek Big Blue. Are yours?

 

[Sponsor]

 

[Seiyafan]

Yep, it's the real one, has Pentek sticker on it.

I tightened the sump with a wrench a bit more, closed valves on both the inlet and outlet and observed the pressure gauge, it's still moving down but very slowly, like 1 psi drop every minute.

 

[Reach4]

I put a very light coat my o-rings with Molykote-111, but you could use similar, or or https://www.danco.com/product/0-5-oz-silicone-faucet-grease/ Danco 88693, which is probably available locally.

The 5.3 ounce tube of Molykote 111 is a lifetime supply.

I would examine the o-rings with your best magnification.

But sometimes you do need to give the housing maybe 1/8 turn with a wrench. I would have thought that would be enough.

So when I screw the housing in, I start by going CCW, until I feel the click of dropping down a thread. Then go clockwise. That avoids cross-threading. I might even go a full turn past the first click and make sure there is no other click until I get to the same spot if I worry that I might have cross-threaded. I don't think I have cross-threaded my BB, but I do the CCW on things when I want to be careful.

 

[Seiyafan]

It lost only 1 psi in the last 20 minutes, looking better now.

 

[Reach4]

I would get a spare o-ring or two. Usually you can reuse, but sometimes you can't.

Here are my o-ring notes on that:
Pentek O-ring 151122
Culligan OR-100
Ace Hardware 4001756 http://www.acehardware.com/product/index.jsp?productId=1275796
Ace Hardware 49561
American Plumber W 10-OR and 152032. 151122, UPC 33663005082, OR-100.
approximately 5.465 inch (inside diameter).

 

[Seiyafan]

Pressure loss was 4.5 psi in the last 9 hours, basically 1 psi drop every 2 hours. All joints are visibly dry, filter housing and sump are also dry, there's no sign of water leak. Can this condition be safe to move on?

 

[Reach4]

I think your testing method is not normal. If you see no water while the filter is under pressure, move on.

Since water is incompressible, what you are doing to test is too much to expect.

 

[Plumber69]

Your probly losing a bit of air theu the top bleeder button

 

[Seiyafan]

It could be the gases that were dissolve in the water escaped somehow.

 

[Reach4]

It could be the gases that were dissolve in the water escaped somehow.

Could be pne of your valves has a tiny tiny leak. In a closed no-air system, how many nanoliters have to leak to drop 1 psi?
Could be that the plastic housing relaxes a bit. I think this one has merit.
Could be temperature dropped, tho that is unlikely I think; most water supplies are cooler than ambient.
Air out of the pressure bleeder sounded good.