My Cheap Fermentation Temperature Control

I built this fermentation temperature control system to be cheap and not take up too much space in my condo. On my first few brews I only used a tub of water and some frozen water bottles, but that ended up being inadequate as ambient temperatures where I live are often above 80 degrees F.

This set up utilized a 20 ft piece of 3/8 in. outer diameter copper tubing that cost around $13 at the hardware store, an old sleeping bag, a plastic storage container that I already had, an old 2 gallon cooler, a fountain pump I got from Amazon for $12, two pieces of 3/8 in. inner diameter vinyl tubing, some teflon tape, and a two hose clamps. To control the system, I used a Lux Win 100 thermostat that I modified by splicing several feet of wire to extend the reach of the temperature probe. I've been using a 6 gallon better bottle as my fermenter and it's been working great with this system.

To modify the termostat, I cut the short external wire attached to the temperature probe. That left just enough wire coming from the probe and the thermostat for me to solder in a few feet of 18 gauge wire.

To actually remove heat from my fermentor, I arranged the copper tubing into a coil that fits tightly around my better bottle and attached a length of vinyl tubing to each end with hose clamps. I pump cold water into the top of the tube with the fountain pump. I couldn't find an adapter at my hardware store to fit my 3/8 inch tubing to my fountain pump, so I wrapped a bunch of teflon tape around the tip of the tube I attached to the pump until I had a nice tight fit.

To keep the water that I pump through the copper coil cold, I keep the pump in the 2 gallon cooler and change the ice two or three times per day.

I set the carboy into the plastic storage tub and stuff the sleeping bag around the Better Bottle. The picture below shows the better bottle wrapped up in the sleeping bag on the left. The cooler with the pump and frozen ice bottles is on the right. I tape the temperature probe to the Better Bottle and tape a piece of cardboard over the probe. The power cable from the pump gets hooked up to the thermostat and switches on the pump to keep my beer at the correct temperature.

The picture below shows the copper tubing wrapped around the Better Bottle beneath the sleeping bag, as the cooling system keeps my ale fermenting at 60 degrees F.

So far, the coldest I've been able to keep a fermentation with this system was 60 Degrees F. That was a five gallon batch of 1.075 gravity ale that I fermented with Pacman yeast. I'm sure a digital temperature control would be better than the thermostat, but this system currently keeps the beer at my selected temperature, or one degree F below (at least according to the display on the thermostat). This system is also great because it doesn't take up much space in my condo when it's not in use.

I'm thinking about upgrading this system by replacing the cooler of ice and water with a container of water in the small refrigerator I currently use to hold my beer. I would modify the refrigerator to accommodate the vinyl tubing and power cable from the pump. I'm thinking of possibly putting a slit in the magnetic stripping on the door to accomodate the tubing and power cable.