Would this concept work? Small mini freezer with 3 gallon reservoir for propylene glycol mixture. Fridge plugs into inkbird. Inkbird probe in glycol mix, set to 28F. Inside reservoir is small submersible pump. Pump plugs into second inkbird. That inkbird probe goes into fermentation vessel on outside of fridge. Set to fermentation temp. Theory is that pump only kicks on and circulates glycol through cooling coils (like what Blichman makes) when temp of beer goes above range. Obviously would have to (safely) drill holes in freezer walls for glycol supply and return lines, plug for pump, and inkbird probe (if desired). In theory, freezer kicks on when glycol mixture goes above its range, (say 28-38F), and pump kicks on to circulate glycol when beer goes out of range (1-3F differential). Thoughts?
I think this works in principle. In fact I seem to remember seeing a description of this from someone who had done it or something similar, maybe on YouTube. Personally I wouldn't fuck around with propylene glycol though. Not because it's dangerous (it's not), but because it costs money and seems like a headache. I would just use 35°F or whatever water. That should be plenty cold to do the trick. I would watch out for condensation on the coils and other lines external to the freezer. Not going to be a problem for the beer itself, since it's enclosed, but could get moldy or just generally create issues for you.
Not only would this work, I think you just described how large commercial breweries maintain their ferm temps (although with specific-built equipment). However . . . you knew this was coming . . . my experience with crafting specialty equipment like this is a couple of attempts are usually required. I.E, the prototype rarely meets the need. But in truth this is the hallmark of a homebrewer . . . keep at it till you prevail. A couple of caveats: Agree with minder, don't fuck around with glycol when good ole water in the 30s has a great history of cooling wort. Not even sure if a submersible pump would work in the green stuff (really don't know). If you have a Blichmann-type coil in the primary I'm pretty sure you'll have some sort of thermowell/temp-probe to get accurate temps. IMO accurately knowing the wort temp is the most critical part of the operation. Everything else is just an exercise in plumbing. Rather than fabricate/assemble your chiller, why not explore some of the commercial offerings? Here's a chill-water cooling system that's reasonably priced that has at least one homebrewer review: https://www.amazon.com/Active-Aqua-...water+chiller&qid=1561757913&s=gateway&sr=8-3 If you go the DIY route I'd be interested in photos of the finished product.
You risk freezing the water if you are not using glycol. Yes water will not freeze above 32 but the freezers coils are much colder than 32. The freezer only has one cold temperature, and the coils remove heat for as long as the compressor is on. But the coils are much colder than 32. Below 0F in fact. Even when the compressor is off the cooling coil is still absorbing heat well below 32 and there is going to be some temperature creep. Glycol is not difficult to use. A 1 to 3 mixture freezes at 14F. You can experiment with the shut shut off temp as well as the delay and possibly dial it in so you are getting the temperatures you need. Having air as the heat removal unit is less than ideal. Liquid to liquid transfer is much more efficient. We have seen two commercial accounts, one a small brewery and the other a bar that were using a DIY system. Honestly both systems did not work very well at all. FYI, the smallest commercial chiller is 1/6 hp and made by Vin Service. But really any 1/6 hp unit is more than enough. They are about $650. A cheaper option is a hydroponics water chiller. As low as 1/10 hp but I am guessing 1/10 hp is too little. Cheers
I toyed around with making my own chiller. I usually try to make things myself if I can. But, size and aesthetics was going to be an issue since my fermenter is in a visible area(not the basement). So I caved in and bought a 1/5 hp chiller. It was more expensive, but, it was smaller than what I could build, and nice looking. It works great and I think that it was worth it for me. That's obviously a judgement call for everyone. I'm in the South, and tap water via the coil chiller was just not going to cut it. It works fine for the winter.
