Temperature Controller Fluctuation

[bulbous_blues]

Hi

Can anyone with experience of temp controllers advise me. I have a 5 cu ft black and decker chest freezer with an Auber TD100a dual temp controller. I have a 6.5 gallon brew bucket with water in it and a thermowell through the lid and the probe in that. I've been testing it out and I found that if I have a cool temp set for say 67 degrees the temp controller will turn the freezer off but the temp just keeps dropping, down to at least 60 degrees. I added a computer fan which seemed to help a little. Am I missing something? Is this normal? Do I need more circulation, is the freezer to small?

Thanks

 

[day_trippr]

Chest freezers have that over-shoot pretty much built-in - turning off the compressor doesn't "turn off" the refrigerant that just got injected into the evaporator loop.

That said, I'm surprised that a thermowell in a 5+ gallon bucket of beer would see that big of an overshoot - unless the controller was running amuck, or the settings weren't what were actually intended. If the probe was measuring air temperature, that's a whole 'nuther story as you'd see humongous spikes, but the hysteresis provided by that large a volume of fluid shouldn't see that big a swing in the beer temperature.

Given years of experience with controllers used for fermenting in fridges and dispensing from chest freezers, I'd conclude that something ain't right...

Cheers!

 

[bulbous_blues]

OK I'm gonna give it another look tomorrow, see whats up. Sit and and watch dam thing see what happens exactly. Thanks for the reply