Author Topic: Using External Thermostat in Frost Free Freezer  (Read 280 times)

Offline aleman1949

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Using External Thermostat in Frost Free Freezer
« on: June 21, 2019, 06:55:35 PM »
I'm planning on using a frost free/auto defrost freezer as a fermentation chamber, using an external thermostat to maintain fermentation temp. The freezer is frost free. I understand that using the external thermostat to maintain temperatures above the designed operating temperature can "confuse" the auto defrost controls. Does anyone out there know what concerns I should have on doing this? Will I end up ruining the freezer? Is there a way to temporarily disable the auto defrost while I am using the freezer as a fermenter?

Offline Bob357

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Re: Using External Thermostat in Frost Free Freezer
« Reply #1 on: June 21, 2019, 07:25:41 PM »
Not sure about the latest technology being used, but on the older models the defrost cycle was controlled by a timer. Since the external controller is cutting power to the unit I would think the timer would reset with every off cycle, so the defrost cycle shouldn't run at all.
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Offline charlie

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Re: Using External Thermostat in Frost Free Freezer
« Reply #2 on: July 12, 2019, 08:16:37 PM »
My first fermentation chamber was a frost free freezer. I used a Ranco single stage controller and wired it directly to the freezer's power cord so that it came on only when the controller called for cooling.

Look up your freezer's manufacturer and model number and download the schematic. If you're lucky there's a schematic on the back of the freezer that shows you exactly where to interrupt power to the defroster.

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Offline Bilsch

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Re: Using External Thermostat in Frost Free Freezer
« Reply #3 on: July 15, 2019, 02:30:48 AM »
Defrost timers are generally based on compressor on time and eventually will interrupt your external controller but the timers are easy to wire around.

Offline fahrphrompuken

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Re: Using External Thermostat in Frost Free Freezer
« Reply #4 on: July 15, 2019, 04:11:33 PM »
So this must be an upright freezer. You could pull the cover off the evaporator coils, usually a panel in the back wall of the unit, and disconnect the hot side of the heating element, or completely remove the element and use electrical tape or heat shrink tubing to insulate the wires. The timer is probably built into the main circuit board. So you could remove the heating element wires at the board and tuck them safely away.

Offline Bilsch

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Re: Using External Thermostat in Frost Free Freezer
« Reply #5 on: July 16, 2019, 04:07:28 AM »
Timers look like this and are generally sitting right in the open next to the compressor.

https://www.google.com/search?q=freezer+defrost+timer&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj5qca8x7jjAhWJsJ4KHVm3BHYQ_AUIESgC&biw=1066&bih=904

They have 4 wires with two wires being heavier gauge. Normally it's just a matter of pulling the two larger gauge wires off the timer and and connecting them.
« Last Edit: July 16, 2019, 05:08:03 AM by Bilsch »