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Fermzilla and a thermowell

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sounddoc

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Long shot here, but has anyone made a DIY thermowell for the Fermzilla that's able to be used under pressure? As temps are getting lower here in Maine, I'm not able to rely on my steady 68F in the brewing chamber (AKA the bathroom). I know Kegland sells one, but as far as I can tell they don't ship to the US (the thermowell isn't available on kegland.cn either).

I can certainly get long enough SS tubing needed at a number of places, but before I go drilling into the top cap of the FermZilla, I'm unsure as to what hardware to use on the cap to make a proper seal which will not only hold the thermowell in place, but also handle 15 or so psi during fermentation.

Thanks folks!
 
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sounddoc

sounddoc

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Got the parts today and dry fitted them. Used a step drill to 3/4" to match the thermowell and it was TIGHT. Using a dremel I "widened" the hole a bit leading to some melting - not great considering this is a brand new fermenter on a budget! but it all worked out in the end. I ended up tapping the hole with the thermowell and with the top washer and o-ring, there's not much thread left underneath. It's a really tight fit so tomorrow I'll dump 5 gallons of saved wort chiller runoff (gardening season is over up here) into it, pressurize it to 15 or so PSI and let it sit for the day. If it's still 15psi when the kids are fighting going to bed, i'll consider this a win.

Oh, and the 400mm length is perfect - almost tailor made. Tomorrow I'll also be building an enclosure and wiring up the STC-1000 for temperature control.

IMG_20191024_184845.jpg IMG_20191024_184853.jpg IMG_20191024_184908.jpg
 
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sounddoc

sounddoc

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Failure!!!

right off the bat there was leaking. I took it apart, buffed the threads a bit more and resealed, but still leaks. there's not enough purchase on the bottom to get the nut on there with both o-rings, so i think i'm SOL. I tried sealing from the bottom only with an o-ring and the nut but still no joy.

Would it be possible to seal up the top, sans o-ring (having just the o ring / nut underneath) with something like JB weld? or putty? grout? The key would really be to keep the seal for pressurized fermentation. I wonder if different, flatter o-rings would help? These are the red round ones you'd find on a ball valve for a brew kettle - they seal for liquid but obviously not gas!

Ah, well, hopefully this thread helps someone else at least.
 
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sounddoc

sounddoc

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Not Failure!!!

An update - I went for it and teflon taped the hell out of the thermowell. It "held" pressure! not great, but only was losing about 1 psi per hour - this could have also been because of the water absorbing C02, but not sure.

Anyway, I decided to give it a whirl, and I currently have a best bitter fermenting at 20C (DIY STC 1000 for the win) with Wyeast 1469 and it's holding a steady 8psi courtesy of the spunding valve!

So maybe only a partial failure. I'll update this thread once fermentation is complete and I rack to a keg doing a pressure transfer. Thanks for reading!
 
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Success!!!*

Pressure held throughout fermentation, even after FG was reached. I know Wyeast 1469 is a busy yeast, but the hefty teflon additions to the thermowell must have done the trick. So if anyone is willing to try this, I used the 400mm thermowell from amazon linked above, step drilled the fermzilla cap to match the inner thread diameter on the thermowell, cleaned it up a bit with a Dremel, then used the thermowell to "self-tap" itself into the cap. After that I uber-teflon'd the thermowell, screwed it in TIGHT, and from underneath the cap put in one of the supplied o-rings and then the nut. It's hard to tighten it all together, but seemed to work out in the end. Post-fermentation, pressure never went below 5psi by itself with the spunding valve set at 10ish psi.

*YMMV - replacement caps for the Fermzilla are mercifully cheap. Buy one in advance :D
 
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