Home Brew – Freezer to fermentation chamber conversion

For my home brew endeavors I had another problem to solve… a temperature controlled chamber for fermentation.

I had the following constraints/requirements:

1. Get it cold enough (10 – 15℃) for lager yeast. I live in a hot climate.
2. Large enough to allow my 30 litre fermenter (H:530mm,Dia:300mm) or my 6.5gal glass carboy (H:520mm, Dia:305mm) to fit.
3. Rather precise  temperature accuracy (~0.5℃)
4. Not cost “a lot”.

I decided that buying a suitably sized chest freezer and putting in a digital thermostat would be the way to go – Here’s what I bought:

1. Chest Freezer – Farfalla FCF-128A
– $299
– 128 litres
– External dimensions (W:750, H:780, D490)
– Available area for full-size fermenter (H:580, W: 382) (i.e. not including space above the “step”/”bump” inside the freezer due to the compressor)

2. Digital Thermostat – FOX1004

– $80
– Range 40.0 to 90.0℃
– 1 relay, 250 VAC 2A. Note: Not rated high enough to take full compressor load, hence the need for the contactor
– External dimensions (W:770, H:350, D:770)
– Input sensor diode(wire length : 3 metres)
– Input 230VAC 50/60Hz

3. Contactor – Schneider LC1K0901M

– $25
– TeSys K contactor
– 3P(3 NO) – AC-3 – <= 440 V 9 A
– 220…230 V AC coil

Now time to wire everything up.

Here is how I did it (click on the image to make it larger)

CircuitDiagram v0.2

The finished product


Note the thermometer probe is in the bowl filled with liquid – this will ensure a closer match to the actual beer temperature. Also, I put a battery powered (for now) fan in the chamber for circulation – need put in a better solution.


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