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-   -   mini cold box project. (http://www.homebrewtalk.com/f51/mini-cold-box-project-19549/)

Uncle Argyle 01-13-2007 07:40 PM

mini cold box project.
I was reading a project that Dude had posted (http://www.homebrewtalk.com/showthre...t=14907&page=4) and thought about making a mini cold box...basically using a 1.7 cu ft. dorm fridge. The storage are would be just big enough to house 2 cornies (CO2 would be outside).

My question is...would this fridge this small be strong enough to bring 2 cornies down to the correct temprature?



mcody2005 01-15-2007 01:43 AM

this is a tricky question. If the box can "maintain" you desired temperature when empty, than it is strong enough to keep anything you put inside it,(provided that this item is at target temperature) be It a huge block of lead or just air at your target temperature. Heat itself is what flows. cold dosent flow. to maintain a temperature lower than than the temperature outside the box, your fridge only has to compensate for the heat that flows through the insulation into the box from the warmer outside air. if what you put in the box is at or close to your taget temp, it will work fine.
Now if you put a large mass of warm or hot matter in the box, your fridge will still need to compenate for its own lacking insulation, and at the same time be burdoned with pumping out the heat of the added mass untill it reaches target temp. on a small fridge, this may cause the compressor to run for much longer than it;s designers ever intended. and the rate at wich it cools will probably be slower than what you intended.
my advice- cool it to as close to the target temperature and see what happens

Uncle Argyle 01-15-2007 04:03 AM

I am hoping that I would be able to place a keg filled at room temprature and have the cold box cool it down to the 38 degrees. Presently, I have no other means of cooling the keg to the target temp.

I might just go ahead and try putting something together and see if I can get it to work. Once I give it a go, I'll post the results for anyone interested.

mcody2005 01-15-2007 04:10 AM

it would benefeit you to place a box fan blowing directly on the fridges condesor coil. (the hot snakelike tubing that zigzags across the back of the fridge). At least untill you get the keg down to temp. this will reduce the cooling time and reduce the load on the fridges compressor.

Brewiz 01-15-2007 01:13 PM

I did something like that years ago by attaching an apartment size fridge to a small chest freezer that didn't work anymore. I could easily get it down to the low 30's. Just make sure it's well insulated and sealed.

Uncle Argyle 01-15-2007 03:27 PM

Thanks mcody2005 for the assistance and brewiz for the experience. Amy recommendations as to the type of insulation that should be used?

Brewiz 01-15-2007 03:31 PM

Check out this thread it may help.

runhard 01-15-2007 04:58 PM


Originally Posted by Brewiz
I did something like that years ago by attaching an apartment size fridge to a small chest freezer that didn't work anymore. I could easily get it down to the low 30's. Just make sure it's well insulated and sealed.

That's a great idea. I see chest freezers as well as uprights and refrigerators that are in the large item trash pickup every once in awhile. I guess a 1.5-2.0 cu. ft. dorm size refrigerator might work?

Brewiz 01-15-2007 06:36 PM

That's what I used, it worked for about 10 yrs. I could replace the fridge part and use it to lager but I have a better idea I want to try using an full size fridge.

mcody2005 01-16-2007 01:05 AM

if you plan on building the cabinet yourself, your best bet would be Rigid Polyurethane Foam Board Insulation. this is the pink or blue sheets of foam found at home improvement stores. Pick the one with the highest "R-Value" this is the rating on how well the foam insulates. make sure that you dont use the insulation itself as the primary building material as this stuff is delicate, and dents and generale abuse will decrease its efficency. In other words, make sure the foam is sandwiched between a durable inside and outside layer( probably plywood). The smaller you make box the less surfice area it will have and the better it will work.
this project seems like it would be alot of fun, but you can grab an old chest cooler go for it! I know i would.

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