Many people have the goal to make great tasting and looking mead. With so many variables in the mead making process, temperature is one that rates among the most important to control. But for most weekend worrier mazers a solution that won’t break the bank and solve the temperature problem is hard to come by.

There are many options like setting up a swamp cooler with your fermenter in a tub with ice water and wrapping it in something that stays wet. It’s not a very sophisticated process but you’ll need to ensure the water is cold and the wrap is wet. Another option is the modified refrigerator/freezer with a temperature controller. This requires space and limits you to either one batch, multiple batches each in their own refrigerator or running several batches together at the same temperature profile. Then there’s the cold, dark spot in a closet or basement…..

I decided that a system to control each fermenter individually was the way to go. A scaled down version of a central chiller system found in almost every commercial production facility, and many of my own, was the solution, but how to do this without breaking the bank was the question.

Searching the internet there are a lot of great ideas on building your own chiller, but the problem was how to control the temperatures

of each fermenter without being jacketed. There are cooling jackets you can buy, but they were out of budget for this project. The solution was to wrap a copper coil around the fermenter. So just like a jacketed fermenter or tee shirt in a swamp cooler, the 32o water running through the coil would transfer heat out of the must.  A little insulated shopping bag from the local supermarket and a Velcro strip to hold it in place and you’re done. Keeping the coil as tight as possible around the fermenter is key. Side note, ours are plastic big mouth bubblers, not so sure this would be ok on glass carboys without a barrier between the glass and the copper.














With that problem solved, I was off to the races! Now to find an AC unit that would be big enough to run three of these. Luckily in my shed I happened to have a 5,500 BTU AC window unit. Right next to that was the perfect 34 quart Coleman cooler. A marriage made right in front of me!

Next: modify the AC unit and eliminate the unnecessary parts, such as the thermostat, evaporator fan, and base. You want to remove the AC thermostat, as the temperature controller will replace that. Just pull the switch out and connect the two wires from the switch together. If your AC unit has a separate power and temperature switch, make sure you mark which is which and the corresponding positions. The unit power should always be set to ON and the temp setting to HI COOL.

VERY IMPORTANT NOTE: you want the evaporator coil in the cooler! That’s the side that would normally be facing in the room. Don’t disturb anything on the other side of the AC.

In the picture above you can see I’ve removed the covers and the evaporator fan. If you’re lucky as I was, this unit had a plastic base, making removing it to fit the cooler up close a breeze. I was able to cut off the base just behind the fan/compressor line. I trimmed the fan shaft as well and that’s ok, there’s no balancing issue cutting down the shaft. Then I lined up the cooler with the AC unit, a few more cuts, and slipped the cooler from underneath and captured the evaporator coil. No bending required of VERY delicate tubbing with Freon in it. See pictures below.

This was all mounted to a piece of plywood that I also had in the shed. I used a few screws and some L brackets to keep the cooler and AC unit from separating; patched up the slot where the coil lines came in and its water tight again. Make sure your cooler has a drain plug! You’ll want this so you can drain the cooler after testing the entire system with water! The last thing you want is to fill up the system with water/glycol mix and have a leak.

Here’s a look at the finished chiller. The temperature controller next to the cooler turns the AC unit on/off based on the temperature of the cooling fluid. I used a model WILLHI 1436 temp controller/digital thermostat. The pump is a submersible pond pump rated for 920 GPH. I went big here to ensure adequate flow to all three fermenters and used ½” ID tubing.















From here you can go two ways: either a central system run by one pump or an individual pump for each fermenter. Now the size of your cooler and the number and size of the individual pumps will determine how many fermenters you can set up. I chose yo go with a central pump and created a piping system that is found in commercial processing with supply and return lines.

Each station had valves, a temperature controller and solenoid valve to turn water flow on and off based on setting of the controller. If you go with individual pumps, the temperature controller will cycle the pump on and off instead of the solenoid valves. You’ll be running a set of hoses (supply and return) between each fermenter and the chiller. This also means more holes on your chiller tank.

The picture on the left is from the early stages of construction. The bottom pipe run is the supply, the top pipe run is the return. Not shown here is a valve that was added between the supply and return. That’s need to limit the flow going through the loop. You want to maintain pressure to each fermenter, so this valve will regulate the flow back to the chiller tank. If none of the fermenters are calling for cooling, the water will still flow around back to the chiller tank, thus ensuring constant flow. Pretty serious stuff, right?






Here’s a picture of an individual fermenter station. The temperature controler is an Inkbird ITC-308 and the valve is a 110vac solenoid with ½” threaded connections. All the PVC pipe is ½” schedule 40 and I used 3/8” ID tubing for the fermenters. The thermostat goes in the stopper well in your must. The solenoid valve gets plugged into the cooling outlet on the controller.










And here is the system as it stands today. You’ll need to watch the fluid flow and adjust the return valves accordingly to enusre you’re getting adequate flow. You’ll also see the fermenters are set on broiler pans. This is to catch the condensation from the copper coils when the humidity gets up there. Yeah, I know, silly but it works!

I built the table, again with material I had laying around.

I’m very happy so far with the system we built. Our 15 gal conical fermenter not shown will have a stainless steel wort chiller in the must. This will allow us to get the cold crash temperatures really needed. Currently the copper wrapped fermenters only get to 44o. Our total investment so far has been about $485 USD and our mead is coming out better than ever before and faster. I hope you find this informative and good luck building your own, Cheers!

Roger Wanner
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