Window AC Unit on external temp controller for lager fermentation

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NBBrewer
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Window AC Unit on external temp controller for lager fermentation

Post by NBBrewer » Wed Sep 09, 2020 6:06 am

Like the title says except in the lower left hand corner of the photo the copper thermostat/ thermister/ temp control or whatever didnt do what i thought it would and keep the temp at a constant 12 degrees. Instead it cycles on and off frequently between 14 and 19. Could it be that my AC thermostat is bad and should I get a new one or bypass the thermostat or even wire the compressor directly to Inkbird 308?
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D.Pepper
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Re: Window AC Unit on external temp controller for lager fermentation

Post by D.Pepper » Wed Sep 09, 2020 7:53 am

Hey Dean,
Chances are one, or either of your thermostats is not calibrated. With the Inkbird system, I would leave the A/C unit on full blast and let the Inkbird manage the temperature. Leaving the temperature sensor out in the air by itself might be whats giving you a higher temperature, as air carries a lower heat capacity than liquid. You could place the sensors in a cup of water and you'll likely see the temperatures drift closer to your expected values.

A perfect system in theory would hold your exact desired temperature, but in application the A/C unit will shut off a couple degrees cooler than your expected temp, and then turn back on a couple degrees higher. This is mainly to save your A/C unit from turning on/off many times which works the unit hard, and also your electrical bill.

Cheers,
Pepper

NBBrewer
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Re: Window AC Unit on external temp controller for lager fermentation

Post by NBBrewer » Wed Sep 09, 2020 9:08 pm

Thanks Pepper I will try that. I got the fridge for the same purpose of fermentation temp control too.

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Re: Window AC Unit on external temp controller for lager fermentation

Post by RubberToe » Fri Sep 11, 2020 1:36 pm

I have a similar setup (seen somewhere in my build thread) and have my AC on full blast to let my temp controller do the work.
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NBBrewer
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Re: Window AC Unit on external temp controller for lager fermentation

Post by NBBrewer » Wed Sep 16, 2020 5:56 am

I realized after careful inspection that my unit has 2 thermistors. One for room temperature or fan temperature and another for coil temperature. I pulled them both out and voila it worked. Still not sure which is which. Temperature went down to 12 degrees quite quickly. Then it turned off. Then it didn't turn back on. Now I need to consult my electrician friend to hard wire the fan and compressor by bypassing the control board.

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