Before putting this together I had tried using a Peltier based cooler, that did work to chill down a reservoir of cool water, but ultimately did not have enough power to cool fermenting beer more than a couple of degrees below ambient temp. This setup is more complex, but makes me happier.
The rather jaunty image shows the chiller in dual use for fermenter and serving (ignore the mini keg also present, lockdown over indulgence).
- Maxi110 off ebay (price varies wildly, but if you can collect should find one under £100)
- STC-1000 (12V version) £6
- 12V power supply £6, rated at 36W/3A to provide power to heater in fermenter
- coolant £15, about 5L of Prestone antifreeze, I really confused myself on antifreeze types & metal corrosion, but settled on this
- 3/8 beer line
- John Guest fittings £? expensive but neat. To connect to the fermenter I used 2 John Guest Straight Adaptor 3/8 inch Tube OD x 3/8 inch BSP Male Thread, PI011213S
- pipe insulation £3 10mm x 9mm Air Conditioner Heat Insulation Pipe
- Thermowell £3, Stainless Steel OD6mm - I had a temp sensor fail (^ see observation about -20°C), this will make replacing the sensor easier, next time
- 3-way mains switch £?. I had some left from another project
- 4 pole panel mount socket to connect the fermenter to the cooler £3, Sensor Connector M12 A Type 4 Pins, I couldn't find 3 pin versions cheaply, the pinout is the same between 3 & 4 pin versions
- 12V relay to switch the 240V Maxi110 pump, you may be able to purchase a unit, I was sufficiently confident to build & appropriately insulate my own circuit
- Wago connector blocks, personally I prefer these over the 1/4" spade connectors
Usually the recirc/python pump is not running, this means that the agitator propeller is also not running. This has not caused a problem but probably reduces the efficiency of the whole thing. I would like to build in separate pump & agitator motors, but that'll need to wait for my next fettling in the shed appointment.
If it is of use or interest, maybe I should post more details of the build, but otherwise thank you for all the information on these forums!