I was recently able to get a nice deal on a chest freezer that is perfect size for a carboy/bucket and still has a good amount of space for some bottles or other things. Right away I snagged a Johnson temperature controller off Amazon - http://www.amazon.com/gp/product/B00368D6JA/?tag=skimlinks_replacement-20 - and was getting ready to do my lager brewing tomorrow.
I hooked up the controller just to see how it functioned, got the freezer going, adjusted setpoint to 50F with a 2F differential and watched what happened... well the temp controller showed 48F, shut off, then to my surprise the temp kept dipping... all the way down to 39F. I let the system run for a few hours, but it still seems to overshoot the differential temperature after the controller shuts off - usually down to 41-42F.
Is this common? If so, what are the general rules to compensate and make sure the wort itself maintains the desired average temperature?
Second topic is where to put the temperature probe. I've been reading a lot about taping it to the side of the carboy or bucket itself with some insulation. My concern with this is the following - if you have it reading the wort temperature as described and lets say the wort is hits 51F, the controller will kick on and begin cooling.
Considering the insulation and the probe reading the wort temperature, the controller won't kick off until the wort itself reaches 48F, correct? Seeing as the freezer air temperature will be cooled well below this temperature, won't the wort continue cooling, potentially far below your desired temperature range?
I hooked up the controller just to see how it functioned, got the freezer going, adjusted setpoint to 50F with a 2F differential and watched what happened... well the temp controller showed 48F, shut off, then to my surprise the temp kept dipping... all the way down to 39F. I let the system run for a few hours, but it still seems to overshoot the differential temperature after the controller shuts off - usually down to 41-42F.
Is this common? If so, what are the general rules to compensate and make sure the wort itself maintains the desired average temperature?
Second topic is where to put the temperature probe. I've been reading a lot about taping it to the side of the carboy or bucket itself with some insulation. My concern with this is the following - if you have it reading the wort temperature as described and lets say the wort is hits 51F, the controller will kick on and begin cooling.
Considering the insulation and the probe reading the wort temperature, the controller won't kick off until the wort itself reaches 48F, correct? Seeing as the freezer air temperature will be cooled well below this temperature, won't the wort continue cooling, potentially far below your desired temperature range?
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