Chest Freezer Ferm Chamber (Heat or Cool)

[Buttwidget]

So I wonder about possible damage to your Chest Freezer's compressor as a result of keeping a .3 degree temperature range... Remember, you are using convection to change the amount of heat in a mass of liquid, I would bet that you overshoot your temp in both directions, forcing a yo-yo effect. Where do you measure the temperature of your fermenting mass? I'm sure there is a gradient of heat from the outside of the carboy to the center of the liquid. All I'm saying is that you might be under the illusion that you are controlling the temperature so tightly, and may also be shortening the life of your chest freezer by doing so.

I'm not saying you aren't doing great things, but its certainly worth a longer-term study.

~widget

[NotTechnicallyLegal]

I have a 12oz jar of water which I submerge the temperature probe in the help smooth out the ambient temperature swings in the chest freezer. I typically set 5 degrees F lower than my target ferm temp to account for the heat produced by fermentation. Not perfect I know, and I could tape the probe to the size of my carboy I suppose but I just prefer the 5 degree buffer, I've had good results so far. I know that isn't making the best use of the resolution of the controller, but I like that degree of precision, even if I'm not necessarily being completely accurate on my wort temps during fermentation.

As far as compresser life and temperature variation, the temp controller unit has some fuzzy logic built in and is a pretty slick little unit. You can set a short-cycle protection time from 1-10 minutes, I've got mine set on 10 so that it won't activate the cooling circuit for 10 minutes after the last call for cooling. It also learns its environment over time, the first few days it cycled a good bit, but now it stabilized into the appropriate range and cuts off temp control early to coast to the target temp (ex, stops the compressor at 62 and lets the temp coast down to 60 based on its past results). So while it does yo-yo at first it learns how to stop pretty quickly.

[Spiderbrewer]

Thanks for the detail. I think I'll put one of these together for my next ale.

Parts List
Electrical Outlet (Lowe's/HD/Hardware store of choice)
Outlet Faceplate (Lowe's/HD/Hardware store of choice)
Electronics Project Box (I got mine at Radio Shack)
Temp Controller (Ebay, link noted before)
14 Gauge Extension Cord (Lowe's/HD/Hardware store of choice)

The controller comes with a temp probe. You basically just cut the receptable end off of the extension cord and use the wiring from it to wire up the controller. I don't have a lot of electrical experience at all and was able to do it in about an hour without much trouble. Just run the extension cord into the bottom of the project box to provide power and then run the temp probe out of the side. Make sure you break the jumper tab off on the outlet (metal tab on the side going between the two outlets), as that lets you switch each outlet indepenently with the controller. This isn't an original design of mine or anything, but the thing works great. Hopefully these extra pics will give you a better idea.