oops made a mistake in overflow plumbing

[andrewkw]

I made a small low profile overflow box for a small tank I built. I accidentally put the gasket on the inside of the overflow box instead of against the tank wall. Thus the bulkhead is leaking. I can only get it out by destroying the overflow box. Of course I only realized this after I glued all my plumbing.

Would putting a second gasket on the bulkhead stop the leak? So I'd have one on the inside against the flange in the box and one more between the tank and the box. Even this is going to be tricky to fix and will require a bunch of new plumbing parts.

Edit now that I've cut the overflow box off I can remove the inside gasket with a knife. Should I? I don't see how having this second gasket could hurt, but if I knew what I was doing I wouldn't have created this thread...

 

[woodnaquanut]

You want to keep the water from getting to the male threads on the BH. Putting a gasket between the internal box and the tank should do that. You might also need to put a gasket between the external box and the tank.

Is your BH long enough to add the two gaskets?

Edit:
After another swig of coffee...
A gasket between tank and external box might be all you need.

 

[andrewkw]

Seems to be fine now with the additional gasket, good thing I had an extra bulkhead! I was smart I didn't glue everything just attached some pvc so and poured water into the overflow to get the gasket and it's staying dry. Thankfully this will be the last thing I plumb for several years.

 

[jbvdhp]

Shouldn't the gasket be inside the overflow box, between the BH and tank? Wasn't that what you did to begin with? Was the gasket new? I know when I try to reuse gaskets they leak. I have to buy new ones.

 

[ca1ore]

Every time I have used an internal box, I have either siliconed the box to the tank wall and then used a gasket under the flange inside the box; or if not using silicone, a gasket under the flange inside the box and then a second one between the box and the tank wall. Either works. You can also flip the flange to the outside of the tank, and then only a single gasket is needed.

 

[andrewkw]

I used 2 new gaskets rending one but not needed bulkhead useless. The tank is acrylic so siliconeing the box probably wouldn't work. To be clear one is on the inside of the overflow and one is between the overflow and the inside of the tank. The nut is on the outside of the tank. So far it seems ok. I just tested by pouring a gallon or so through the overflow box and there were no drips.

 

[mcgyvr]

I just tested by pouring a gallon or so through the overflow box and there were no drips.

Now test it by pouring 1000+ gallons per day for the next 10 years through it

 

[SGT_York]

Not a good solution eventually it will start to drip through the bulkhead threads where there is no seal.

 

[andrewkw]

Not a good solution eventually it will start to drip through the bulkhead threads where there is no seal.

I'm obviously going to glue the pipe. Since I already had to cut it once I tried it with 2 gaskets to make sure the second gasket wouldn't cause an issue. In the test I was onlu concerned with bulkhead leaking.

 

[thejuggernaut]

Does it have an external box?

If no external box you need the gasket between the bulkhead flange and the inside of internal box and another gasket between the internal box and the tank. A gasket on the outside between the tank and the nut is bad. It keeps you from being able to tighten the nut because the gasket causes allot of friction.

If it has an external box, you need a gasket on either side of the glass. The would be Bulkhead flange>internal box>gasket>tank>gasket>external box>bulkhead nut. One is not required between the flange and internal box, but won't hurt.

The outer threads of a bulkhead are not designed to be water tight. They are designed to clamp the bulkhead and gasket to the tank surface. The gasket keeps the water off the threads. By adding extra material between the tank and the bulkhead gasket (internal box), it adds another place for the water to seep into the external threads and drip out the back of the bulkhead through the nut. If you have an external box it doesn't matter if the threads get wet, because the back of the bulkhead is underwater. All you need to do in that case is keep the water from leaking out between the tank and the external box. HTH