Water Cooler/Garbage Can Fermenting Chamber

So I had an old mini fridge lying around that I was going to convert to chill a fermenting chamber until I hit a refrigeration line pulling it apart.

I had already made my lager starter yeast the day before and needed a temperature controlled environment quickly. I had an old water cooler in the garage and searched these forums to see if there were any DIYs on using old water coolers. I couldn't find any but it was all I had and the results are great.

The top comes off the cooler I have so that you can clean the water reservoir, therefore I did not have to modify the water cooler at all. Basically I put my 23 liter carboy in a trash can, filled it up with water to just above the wort level and stuck a $20 water fountain pump in the cooler reservoir. When the water in the trash can goes above setpoint the pump adds a little cold water to maintain setpoint. The water rises above the through hull spigot and drains back to the reservoir.

When designing this I was worried that it would not be able to keep up to the heat loss, but I have maintained 11.5C for five days so far with a variance of .02C. My temperature controller is from an old building automation system and if fully programmable. I have limited the pump run time to 5 seconds every two minutes. In practice, the pump runs on average 5 seconds every 10 minutes. The cooler compressor runs about as often as it would normally, there seems to be almost no load on it.

The great thing about this is that I can fit another 3-4 pumps in the reservoir so I can add another 3-4 garbage can, all with their own temperature control. So from one water cooler I can have a lager at 8C and an ale at 17C.

I know the explanation is probably a little confusing, but I am not sure how to add photos? I will post photos when I figure it out.

 

So here is the 15 minute temperature setup.

By rgostlin at 2011-06-24
Here you can see the temperature probe stuck to the side of the carboy with an elastic band. Also the water makes for a great air lock. On the left you can see the through hull to return the water to the cooler.

By rgostlin at 2011-06-24
This is a shot inside of the cooler, just a pump and I have another sensor to record the cooler temperature.

By rgostlin at 2011-06-24
This is the trend log for the whole setup. The green line is the setpoint and the blue line is the actual temperature. The pink line is the temperature of the chilled water. Nice thing about this controller is that I can program the temperature to rise or fall at a controlled rate.

By rgostlin at 2011-06-24