• TemperatureControl

Temperature Control and Refrigeration

Keeping your ale cosy and lager cool.

I acquired a fridge from the local whitegoods store with a dud thermostat and stuck-on defrost circuit. Since I wasn't planning on using either of these that wasn't so bad.

I tossed around a few ideas and I found that some things people were doing included:

1. Buy a controller from the LHBS for around $100 that the fridge plugs into and you run a temperature sensor inside the fridge. This seemed pretty convenient but being a homebrewer that would be just too easy. I would rather spend $200 making my own

2. Plugging the fridge into a timer switch. Apparently some people have had reasonable success with this. I guess recalibrating for a different temperature would be trial and error. Also when the yeast is really going off it wouldn't compensate.

3. A Jaycar, battery operated thermostat. The nice thing about this is that it has a digital readout, so setting the temperature is real easy and they are only $39. The relay is rated for 3A inductive load. Also I wonder how the electronics would stand up to condensation.

4. I contemplated going the whole hog and designing my own unit with two separate relays to control cooling and heating separately. I still might do this but I am down to well under two kegs and drinking - I couldn't wait. a simple circuit

5. I finally called in on Refrigeration Parts Victoria¹ in Ringwood and they suggested an industrial style thermostat. It is a Fuji Koki U52M and:

   1. Only $AUD37 (This has changed, see note below)

   2. -20 to +30 degrees with a calibrated dial.
   3. Selectable hysteresis.
   4. N/C and N/O contacts, I can use it to heat in the Winter.
   5. The contacts have enough grunt to just about start a car (don't try this at home).
   6. No batteries, no power, just wire it in where the old thermostat was.

   7. The bulb is on a one metre, stainless steel capillary tube. I strap the bulb to the fermenter. This is very effective in controlling the overshoot from initial high heat output of some ale yeasts to the extent that I don't mind pitching a couple of degrees warm, the temperature drops about 2 degrees in an hour.

6. PIC based, serial temperature controller. I haven't tried this but when I free up a PC I might give it a try. Or take a look at the Ozitronics logger kit

7. Digital thermometer and PC software

As at May 2004 RPV have run out of the Fuji Koki 52M - apparently homebrewers suddenly started buying them in bucket loads He has since checked with the Fuji dealer and the price is now $68 + GST. If you want one you should consider calling RPV first. The closest equivalent he has is Saginomiya, these are $55 + GST (at June 2004) and the temp bulb/tube is copper, not stainless.

Quite a few brewers have recommended this unit from Tobins.

When we hit a hot spell, this fridge started tripping the earth leakage breaker (residual current device) a few seconds after it started. I don't believe it is anything to do with the thermostat arrangement I rigged up but don't say I didn't mention it.

As an aside, I was shopping around for some 3/8" copper pipe and the plumbing supplies store was going to charge me over $70, at Refrigeration Parts Vic it cost me $51.

And here is my current setup:

As they say:

• Fridge: $0
• Thermostat: $37
• Beer all year round: priceless

The temperature sensing element is the bulb on the end of the coil. The scale is a bit glared out but with the black knob on the right side of the unit you select the temperature. You need to take the cover off to adjust the hysteresis.

The hole through which you can see some wiring is where the original thermostat mounted.

Now I strap the temperature sensor to the fermenter to control the temperature much better. When the bulb was just in the airspace of the fridge, "hot" yeasts would raise the temperature several degrees celsius. Now the fridge stays on until the wort is at target temperature and stays there. I can get about 2°C drop per hour for a 23 litre batch.

The smaller plastic container in the background is a PartyKeg.

And the business end ...

No special equipment here except a fridge.

After about 2 years of service as a beer fridge (close to 20 years all up), this fridge croaked it. I hot wired the thermostat and found out that is all that was wrong with it. So it was back to RPV for an industrial controller (Johnson) - $66, not nearly as good value as the Fuji Koki was but still for the sake of beer.

paul sorenson