My Brew-fridge

[jupiter]

hi all.

today i finally got a hold of an old fridge to put my fermenter in. it was well needed as i've been brewing between 24 and 26degC (bit too high i've heard). i was hoping it was going to be big enough to fit 2 fermenters, but it falls a few cm short. it used to belong to the Murdoch University Engineering Student Society (MESS) but they ditched it. it has had a pretty rough life but it still works...

but only just as a found out today.

i got it home and plugged it in. it fired up, the element went cold and the thermostat worked. cool i thought. so time to wire in my temperature control.

Temperature Control and logging
to control the temperature i'm using a DataTaker DT50. these have 5 differential (10 single ended) analog input channels, 5 digital IO channels and 4 high speed counter channels. i'm only using 4 of the analog channels for K-type thermocouples and 2 digital IO channels. i have it programmed so that at a brew temperature above 18.5degC the fridge compressor switches on, and below 18.0degC the heatbelt will switch on (i'll tweak these values later). 4 temperatures are being logged, Ambient, Fridge, the brew in the fridge and the temperature of a second fermenter if needed. the digital IO feeds a 4-channel 10A relay board (modified kit from altronics) to switch the 240V.

Wiring it in
i thought this was going to be easy, but ended up being a total pain in the butt because after examining the wiring, the whole fridge needed to be rewired :angry: . the insultion for the existing mains wires had basically turned to jelly-goo. at the plug and the terminal block in the back the insulation had come off completely in places and there were explosed conductors and obvious signs of burning. all the wires in the screw terminals were soldered (a big no-no, you don't put soldered wires in pressure fittings. even stated clearly in AS3000). i'm surprised it didn't burn my house down.

it's now wired without the internal thermostat, but is now all better. it's now up and running

i'm left with 2 questions. i usually have 2 brews going at once at different stages, but since i can't get 2 fermenters in the fridge which is the most vital to keep the temperature regulated: the primary or secondary? also, whats the ideal temperature to set it at for 1) ales, 2) lagers?

cheers.

 

[Tyred]

To my knowledge, primary is the most vital. That said, cold conditioning of lagers requires temps around 4 C.

Can you fit a fermenter and a jerry can in the fridge. If you can, then rack to the jerry can as secondary.

Temperature will depend on type of yeast used.
Temp for ales 18-20 C safale
Temp for lagers 10 -14 C saflager

 

[Adamt]

...which is the most vital to keep the temperature regulated: the primary or secondary?

Primary. This is where the crux of the fermentation takes place. Getting the primary right means less time is needed to condition (in a way). For ales, leave in the primary for a week after fermentation has seemingly finished, then bottle without worrying about secondary.

...whats the ideal temperature to set it at for 1) ales, 2) lagers?

To be technical it depends on the yeast and what kind of beer you are fermenting. In a nutshell, 10C for lagers with proper lager yeasts, 18C for most ale yeasts, 20+C for belgians with proper belgian yeasts.

 

[mika]

Hahaha, engineers...they're so geeky

 

[Adamt]

Engineers aren't geeks, scientists are geeks!

Engineers make the geeks' work useful to society!

 

[jupiter]

cheers guys, i was guessing the primary but wasn't sure. the yeasts i've been using so far have been the ones that come with the kits, now i got some more super-brew-powers i'll venture into using some more extravagant yeasts.

already i've run into 2 problems. firstly, the fridge compressor has been running non-stop for the past few hours, it hasn't got far to go to bring the temperature down to 18.5 but the thermal cutout kicked in, which led to problem 2) there is no drip tray under the cooling element in the fridge so straight away it began to defrost onto the top of my fermenter. software should fix the first by cycling the compressor on and off, i've got a pedestal fan blowing on it atm. the second, well i've got to make a drip-tray, until then a coles bag over the top of the fermenter will suffice. i don't like the idea of water pooling on top of the fermenter.

 

[winkle]

Probably telling you the obvious, but have you looked at removing the door shelving etc (or removing the plastic shell entirely) to gain enough room for 2 fermenters?

 

[jupiter]

Probably telling you the obvious, but have you looked at removing the door shelving etc (or removing the plastic shell entirely) to gain enough room for 2 fermenters?

there is definitely no way they will fit side by side even if the door shelves or plastic shell was removed, the fridge is just not wide/deep enough. the only way 2 would come close to fitting is to stack them, then i just miss out by a few cm. it may be advantages to chop the bottom out...

my 2 fermenters are of different dimentions (both still 30L), one is short and fat (primary) the other is tall and thin (secondary). if both were short and fat they would fit, so i may be hunting another short and fat one down shortly.

 

[Coodgee]

I think you are overcomplicating things a bit mate. You don't need to keep the wort at exactly 18 degrees. I would ditch the heat belt and just use the fridge. A good sealing fridge set to 18 degrees should only come on once every 4 hours or so. more when the fermentationi is vigorous.

 

[Phrak]

Ditto what Coodgee said ^^
The heat belt would come in handy for fermenting Ales during the depths of winter, but you'll just be wasting electricty during summer.

You'll find that as long as you keep the fridge door closed as possible, that it will insulate very well.

I have a MashMaster controller that does either heat or cool, but not at the same time. Summer = Cool, Winter = Heat.

 

[jupiter]

i've had ales drop below 14degC in winter and fermentation has stalled, so i'm keeping the heatbelt as part of the system. it shouldn't switch on in summer anyways.

it's supposed to a setup to use for all seasons.

it's all being logged too, so if i find the heatbelt is on when it's not necessary, i'll tweak the setpoint values. easy.