Combo thermometer/Sight glass

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Well-Known Member
Nov 3, 2007
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I bought a weldless thermometer/sight glass from Williams Brewing.

Despite taping that sucker up everywhere, the bulkhead leaks at whatever tightness I adjust to and the little O-rings inside for the thermometer can't hold back water. During my last brew session water flowed out so much it actually got inside the thermometer. I fiddled with that thing for a couple hours yesterday and could not get a good seal anywhere, anyway.

Finally just chucked the whole thing and ordered a large Zymico weldless thermometer. I'll have to pick up a separate sight glass later too.

Anyone else have the same difficulty?
I've never tried weldless fittings except the bulkhead on my cooler. I just think the seal is too borderline. I mean, the keg is curved and the fitting isn't. The Oring has to make up the difference and as you've found, it's hit or miss.

You were having leaks at the thermo compression fitting? Probably not enough Orings shoved in there. You need it to compress before the nut bottoms out.
Either way works. You could even grab some teflon packing rope and stuff it in there. The key is having enough packing to compress prior to the nut bottoming. A stack of Orings (I think 5 of them) was simple enough. Lil Sparky's method is good too.
Lil' Sparky said:
A few tips - put plenty of teflon tape over the fitting that mates with the washer. That's where mine always tried to leak, not where the o-ring was.

For the thermo, I thought the o-rings shoved up inside the compression fitting was hokey, so I did this instead. Works great.

Dang Sparky, that idea is almost as fine as your avatar. I'm going to try it out this weekend. Thanks for the idea.

I would wonder though if the tubing would stand up to 180 heat and not impart any tastes. Small amount of tubing so probably not.
Get rid of the o-rings for the bulkhead all together and use gasket material - problem solved. You could also consider flattening the metal on your keggle a bit to make the surface easier to seal. As far as the compression fitting goes, use 1/4" thermometer and proper 1/4" fitting (no o-rings) - that will fix that problem.
I bought the Zymico weldless thermothingy and am happy with the end result, but was not happy with what it took to install them. The nipples get wider in the center, so they only tighten so far... and not far enough on my keggles. My solution was 2 to 3 SS washers on both sides (after replacing a couple SS nipples). With that, 2 of my 3 thermothingies sealed well, but one (HLT) still leaks a little... a drop every 5 or 10 seconds, so no big deal.