Using old A/C unit for Fermentation unit?

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

EamusCatuli

Well-Known Member
Joined
Jan 21, 2008
Messages
531
Reaction score
1
Location
Chicago
I have an old AC window unit that I do not use anymore but is just sitting around. If I build an insulated box around it (so that it would hook onto the side as if it were in a window) would it make a good fermentation chamber? I think I can set for as low as 58F, which is at least good enough to make reliable ale temperatures.

Thoughts? Waste of time?
 
Make that box big enough to not cycle the compressor too much and I think you'll be happy. Otherwise, I think you'll likely toast the compressor in short time.
 
I'm in process of doing a similar thing (I'm setting up a 10X6 room in the garage) and going to use a window ac to keep it at 65, and from what I've read is that if the AC unit is an older analog type, like a Jonson controller, you can move the the stop point on the thermostat to a lower position, and get the AC to cool to lower temps.
 
Caspio has done this exact same thing, and his chamber has been up and running for a few months now with no problems. A nice thing about this setup is the AC unit is built for circulating the air well, as opposed to a fridge which hardly circulates at all. I highly recommend putting your temperature control sensor in a container with some sort of liquid so that the compressor doesn't cycle on/off too much. I'll post back when I find his build log for the chamber.

Cheers!

EDIT: Here we go...build log: https://www.homebrewtalk.com/f51/fermentation-chiller-v2-106440/
 
Thats awesome and it seems fairly simple - it will have to be something I build later on though because im still in flipping grad school and it would just be too big...great reference though.
 
Bsquared,
I have a 6X6 room in my shop that I put a lager chamber (refrigerator with a cabinet attached) in. The rest of the room, I use for an ale room. Since it is so small, I put a 5200 BTU unit in it (it is supposed to be able to handle a 10X10 room). I also insulated the bajeebus out of it. The outside temp has been around 100F for the last couple of weeks. The AC will keep the temp right at 68 - 70 during the hottest part of the day. All of this to say, make sure you get a big enough AC to get the job done. Good Luck - Dwain
 
Make that box big enough to not cycle the compressor too much and I think you'll be happy. Otherwise, I think you'll likely toast the compressor in short time.

Why would the box being smaller cycle the compressor too much? I would think a well insulated small-ish box would only kick on the AC unit 5-6 times a day and for a short time at that. I was thinking of doing this with a cabinet about 20 cu.ft.
 
Why would the box being smaller cycle the compressor too much? I would think a well insulated small-ish box would only kick on the AC unit 5-6 times a day and for a short time at that. I was thinking of doing this with a cabinet about 20 cu.ft.

I was actually thinking the same thing, smaller the better. right?
 
Meant to pop into this thread a few days ago, I'm too forgetful. THB, thanks for pimping my setup :D

Just a side note: I built the ferm chamber over several weeks in feb. and march. After a week or two of operation, I got around to hooking up a kill-a-watt, and it has remained hooked up for the intervening months. This has covered quite a range of weather, from several weeks where ambient was colder than I wanted the chamber to be, to our current run of 100+ degree temps. I'm scared to know what the temp inside my garage gets to.

Over this time period, the kill-a-watt tells me I'm averaging 25 cents per day of operation costs. So far I've spent $20 to keep things running, with an estimated cost of $100/year. So far, I'm super happy with things. I just need to stop being lazy and keg the 20 gallons of kolsch and IPA I have in there, so I can get on to brewing the next batch :rockin:
 
Bsquared,
I have a 6X6 room in my shop that I put a lager chamber (refrigerator with a cabinet attached) in. The rest of the room, I use for an ale room. Since it is so small, I put a 5200 BTU unit in it (it is supposed to be able to handle a 10X10 room). I also insulated the bajeebus out of it. The outside temp has been around 100F for the last couple of weeks. The AC will keep the temp right at 68 - 70 during the hottest part of the day. All of this to say, make sure you get a big enough AC to get the job done. Good Luck - Dwain

Thanks thanks for the info, I make sure I get at least 5200 btu, we have been having a heat wave down here, I think it got up to 88ºF :), but my garage probably gets up to 95 or so, I only get sun in the AM on it, so I'm planing on insulating the garage door too. I'll see how it goes.
 
Have you guys seen the CoolBot? It's a gadget specifically designed to control room a/c units as walk-in cooler refridgeration. It goes beyond simply overriding the thermostat and also senses coil temps to prevent freeze-ups. It uses some microcontroller intelligence to cycle the a/c. Seems pretty (ahem) cool.

The "science" behind it, as I read it, seems to be that the only differences between a refrigeration and an a/c unit are the larger surface area of the reefer coils and/or fans. both of which prevent coil freeze-ups in "real" reefers. By applying more smarts to the control of the a/c, rather than just a simple thermostat, you can get something for nothing.

It also has the benefit of installation without voiding the a/c warranty (not technically, but in spirit, I would say) so when you burn out the a/c chilling your entire garage to 32f, you can return it :D

It's pricey at $299, but the guy who makes these is a small farmer who is looking for payback on a lot of R&D after he got frustrated with the type of a/c hacks we do here (according to his web site) when trying to cool his "field-hot" produce. Seems like a doo-dad MoreBeer should pick up.
 
Back
Top