Refrigerator or AC unit?

[skidkid267]

I am getting down to business to build a fermentation chamber and was wondering if anyone has experience with using a window mounted AC unit vice a small "dorm style" refrigerator as the cooling unit. Both are options that I have considered and have access to.

Post all your pro-cons.

Thanks

B

 

[Hermit]

Window unit is made to take care of condensation. A small dorm unit may not be. You don't really say what size chamber though. Larger areas will be harder on the dorm unit.

 

[TimWeber]

I just finished my build, one chamber is 4X3X3 and is held at 37F the other chamber is 2X3X3 and sucks cold air from the bigger chamber to keep at 68F.

I am using a window AC unit. I am having issues with ice forming on the evaporator, I have 5 40mm fans blowing over the evaporator which helps, but if the unit has to stay on for too long ice forms and it won't get any colder. Its been in operation for about 2 months now. I love it, but I have to figure out this ice problem. I am trying different locations for the probe currently.

 

[skidkid267]

So ice is an issue on the coils of an AC unit?

The chamber will be fairly small, just enough room to hold two 6gal carboys and a blowoff bucket.

 

[Hermit]

I just finished my build, one chamber is 4X3X3 and is held at 37F the other chamber is 2X3X3 and sucks cold air from the bigger chamber to keep at 68F.

I am using a window AC unit. I am having issues with ice forming on the evaporator, I have 5 40mm fans blowing over the evaporator which helps, but if the unit has to stay on for too long ice forms and it won't get any colder. Its been in operation for about 2 months now. I love it, but I have to figure out this ice problem. I am trying different locations for the probe currently.

It isn't made to go that low, hence the ice. You could try a duty cycle to let the frost clear.

 

[TimWeber]

Yup, Understood. I am forcing it do do something it is not designed to do. I had a spare AC unit lying around. I can't duty cycle it bc I am using a ranco controller at the moment. I might hook my BCS460 up to it at some point.

AC unit might be a little overkill for that then. I can fit 15 carboys in my one chamber and 5 in my other.

If I built it again I would have built it taller. I think the farther from the floor the AC unit it the less likly it is to freeze since it would be colder on the floor and warmer at the top of the chamber.

 

[Hermit]

Yup, Understood. I am forcing it do do something it is not designed to do. I had a spare AC unit lying around. I can't duty cycle it bc I am using a ranco controller at the moment. I might hook my BCS460 up to it at some point.

AC unit might be a little overkill for that then. I can fit 15 carboys in my one chamber and 5 in my other.

If I built it again I would have built it taller. I think the farther from the floor the AC unit it the less likly it is to freeze since it would be colder on the floor and warmer at the top of the chamber.

Try and lower the temp in stages and avoid opening the unit. Once it reaches temp, it will cycle off on its own.

 

[TimWeber]

That's what I do. It actually works great for most of the time, it's only when I am sucking a lot of cold out of it, or I leave the door open for a while, or I put a whole buch of warm carboys in it that it has problems. It turns on for about 15 minutes every 3 hours or so normally. Not bad really. I am pretty happy with it. I am either going to add more insulation or string a bunch of christmas lights infront of the evaporator.

It works great, I just strive for efficiency

 

[david_42]

It's really a matter of size vs capacity. For what you are doing, an A/C unit is probably too much.

If you have room to build something larger, then you might consider a combination fermentation cabinet and conditioning cabinet (AKA cool beer storage) the way Tim did.

I use an A/C unit for the room (about 1/3 of my old garage) and a fridge inside the room for fermentation.

 

[TimWeber]

Thought I'd give you a quick update. I previously had the probe taped to the outside of a carboy, and taped a blanket over top of it. I think it was taking too long to cool down the carboy (20mins) and that is when the ice started to form.

I drilled a hole in a whitelabs vial cap, filled it with water and made a stand for it. I stuck my probe (ranco thermister) though the cap most of the way into the water. This is sititing in a stand I made at the base of my lagering chamber. I think this has solved the problem all together. Ill keep an eye on it over the course of the week.

My thoughts? If you are going to build this thing, go all out. It wouldn't cost that much more to make a larger chamber, and I think its better to have a little too much space than not enough. In a year you'll look at your $500 investment and think, damn I wish it was bigger.

I also use mine for storing cases of beer (I can fit A LOT) and conditioning bottle carbonated beer. I'm looking forward to how this thing handles the summer heat.

I also bolted each of the sides together so that I could take it apart and move it around if I need too. I just used weather stripping on all the edges as a gasket. Keep in mine, you may have to take it apart later on.