Lager Fridge Question

[Axegod]

I have been reading about temperature controllers but have not found an answer to this question.....
Preface: i have good fridge in my basement and it has a freezer on top that we use and need.
I understand that most fridges when hooked up to a temp controller will make the
Freezer thaw. Not good.
If i put a carboy in the fridge in a waterbath/tub and then added a digital temp probe
heating output to control an aquarium heater inside the tub....could i keep my carboy at 50 degrees as long as the fridge is on the lowest setting? I am assuming that my empty fridge would
go down to about 40 degrees on its own...and the aquarium heater could then boost it slightly......

Can anyone see any problems with this? Wil having a warm carboy cause my motor to burn out? D rest may be tricky......

PS. My internal fridge temp settings go from coldest to cold to off...

Cheers

 

[sennister]

I don't think this is a good idea. Every fridge design is a little different but typically what they do is run all the cold air to the freezer up top. Some rely on the dropping cold air for much of the cooling in the fridge part where the thermostat is. When you say the lowest setting in the fridge I assume you mean the hottest. If you mean the coldest you are really going to introduce issues where the two are going to be fighting each other. At best you are going to have a nice increase in your electric bill and worse burn up the compressor as they are not designed to run all the time like that. Rather than a water bath you would likely be better off with an insulated blanket with one of those direct heat pads. You are still introducing heat and they will fight each other.

For what you are risking in costs you would be better off building a fermentation chamber or going with another appliance dedicated for this if you have room.

 

[kwadric]

I've read about people setting up a fridge with a temp controller set to lager temps and then adding a second temp controller hooked up to a heat wrap for ale temps. One of the keys is that they insulated the ale temp carboy to keep the heat in.

Two differences between the above and what you want to do. First, they didn't care what the freezer temp was. And the risk of having your food thaw probably isn't worth taking. Second, the key to keeping the fridge working well is having a large thermal mass at fridge temp. So if I was going to do what you are propping, I'd probably want 10 gal of water at the 37F normal fridge temp and 5gal of beer insulated and with a heat wrap set to 48F.

 

[shelly_belly]

I've been doing my lagers at 45F just because they were getting too vigorous at 48F. If you could do 45F I don't see that putting too much load on it relative to say my kids standing in front of the fridge with the door wide open many times throughout the day. As for a d-rest, I pull the carboy out when the krausen starts to drop and let them finish at room temp. They go from room temp straight to lager temps as I have found no difference in this method and the drop-to-lager-temp-slowly method. I say go for it.

 

[BigFloyd]

Sorry, you can't have your cake and eat it too. When using a fridge as a fermentation chamber (as I do), I forget about the freezer section. It's now empty cold space as far as I'm concerned. I don't care what the temp is in the freezer section. I'm only concerned about the temp of the beer in the bucket in the fridge.

Consider how a temp controller works (using an STC-100 as an example). It's a dual temperature controller. You wire it into a standard 2-plug outlet that you mount in some kind of project box (either homemade or bought at Radio Shack). One (cool) outlet is for the freezer/fridge. Into the other (warm) outlet, you plug some kind of small heater and then put that heater inside the freezer (only during the coldest part of winter here in TX).

Set the target temp (in Celsius) on the STC-1000. Set the tolerance (default is +/-0.5*C). When the temp (as read by the sensor) climbs 0.5*C above the target, it powers up the cool outlet and keeps it energized until the temp drops to the target and then turns it off. Likewise with the warm outlet if it gets 0.5*C too cool. You tape the sensor on the side of the fermenter and place some kind of insulation like bubble wrap over top of it so that it reads the bucket temp and not the air.

You turn the fridge thermostat to its coldest setting and let the controller make the decisions based on your fermentation temp needs.

https://www.homebrewtalk.com/f51/ebay-fish-tank-controller-build-using-wal-mart-parts-261506/


https://www.homebrewtalk.com/f51/ebay-aquarium-temp-controller-build-163849/



http://brewstands.com/fermentation-heater.html

 

[kempshark]

Quick question on this......has anyone noticed what temp the freezer is at when using the fridge as a fermentation chamber? Just wondering if this space would be good for aging some bottles or something?

 

[Axegod]

Thanks for the great replies....love this site.

I actually noticed that i had individual temp settings for the fridge and freezer and both go from coldest to cold to Off....so i turned the fridge part to 95% off and have been holding steady at 52 degerees for almost 24 hrs. I just increased the cold to see if i could dial in 49 or 50 degrees. If so, problem solved so long as my freezer temp remains good. Sometimes a simple solution also works (hopefully).
If i can dial in the lager range ill buy a ready to pitch wort (see magnotta's festa brew) for $30.....and do a run thru on that. I may also buy a corny keg and give that a shot as well since i may not need to buy any lagering equipment.
Cheers

Cheers

 

[BigFloyd]

Thanks for the great replies....love this site.

I actually noticed that i had individual temp settings for the fridge and freezer and both go from coldest to cold to Off.

What you observed is normal for a combo fridge/freezer (to have separate controls for each compartment). They have, however, only one compressor and one thermostat. The fridge temp is regulated by air balance between the two compartments (and, of course, the temp of the freezer).

The problem with trying to use the freezer while using the fridge as a fermenter stems from the fact that, in order to maintain the mass of liquid inside the fermenter at a nice consistent temp, the freezer air temp will fluctuate quite a bit. If you can use it for something where that doesn't hurt, great.