Author Topic: Temp control for fridge/freezer  (Read 1255 times)

Offline beer_crafter

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Temp control for fridge/freezer
« on: April 03, 2012, 10:43:37 AM »
Thinking about using my current fridge as a fermentation fridge.  It's a typical kitchen sized fridge with a top freezer.

If I use a single stage temp controller to keep it at, say, 64, what will this do to the freezer?  Most likely it would not keep the freezer below freezing, right?

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Re: Temp control for fridge/freezer
« Reply #1 on: April 03, 2012, 10:46:30 AM »
probably. the freezer will only run until the fridge (I assume the temp probe will be in the fridge) hits the set point. now, if you set the freezer to it's coldest setting and, at that setting, it is 32+ degrees colder than the fridge then it would still be below freezing I would think. so if the fridge, during normal operation sits at around 45* (I don't know if this is normal or what) and the freezer at it's coldest setting sits at ~10* then you should be good.
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Offline bo

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Re: Temp control for fridge/freezer
« Reply #2 on: April 03, 2012, 10:48:43 AM »
The freezer will be colder, but I would doubt that it will be freezing.

Offline HydraulicSammich

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Re: Temp control for fridge/freezer
« Reply #3 on: April 03, 2012, 11:02:37 AM »
I don't mean to hijack the string but I do need some experience with the temp controller.  I am a first time user of the Ranco 2 stage.  I have cooling set point at 65 with a 2 point differential.  My confusion is the heat set point and differential.  Anyone give me the proper way to set the Heat side?
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Offline DrewG

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Re: Temp control for fridge/freezer
« Reply #4 on: April 03, 2012, 11:20:29 AM »
Quote
I am a first time user of the Ranco 2 stage.  I have cooling set point at 65 with a 2 point differential.  My confusion is the heat set point and differential.  Anyone give me the proper way to set the Heat side?

I have the same controller, using it with a fridge and a fermwrap with a thermowell. If you want to ferment at say 67, you set the heat side to 67 with a 1 differential and the cold side to 67 with a 1 differential and you'll be fine. You're cooling a large enough mass (5 gallons or more of wort) that it wont cycle on and off constantly. Works like a charm.
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Offline DrewG

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Re: Temp control for fridge/freezer
« Reply #5 on: April 03, 2012, 11:24:48 AM »
Quote
If I use a single stage temp controller to keep it at, say, 64, what will this do to the freezer?  Most likely it would not keep the freezer below freezing, right?

Mine never gets much below 45 or 50, but I've only used it this spring in cooler temps. The fridge doesnt have to run much to maintain a carboy at 67 or so. Maybe during the summer? But ambient will be higher too..
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Offline HydraulicSammich

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Re: Temp control for fridge/freezer
« Reply #6 on: April 03, 2012, 11:25:53 AM »
Perfect, thanks Drew
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Offline DrewG

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Re: Temp control for fridge/freezer
« Reply #7 on: April 03, 2012, 11:43:41 AM »
I should add that those settings are good for a thermowell, or if you tape the probe to the side of your carboy and insulate it with cardboard or bubblewrap or whatever. I think if it was just hanging in there taking the ambient temp you'd run into trouble with the settings that close.
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Offline HydraulicSammich

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Re: Temp control for fridge/freezer
« Reply #8 on: April 03, 2012, 11:51:11 AM »
I agree with the thermowell or taped.  I have always taped the probe to the side covered with a good chunk of styrofoam.  My confusion was with the H1 setpoint.  In your application, C1 and H1 set point are the same.  The differential lightens the load on the equipment.
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Online mtnrockhopper

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Re: Temp control for fridge/freezer
« Reply #9 on: April 05, 2012, 06:10:44 AM »
Some older refridgerators work by cooling the freezer air, then using a fan to circulate that air down into the refrigerator. A thermostat turns the fan on when the bottom needs more cold air.  You could probably hook your own thermostat up to that fan if your in the mood for a project. Then the freezer would run as normal, but the refridgerator section would be warmer. If it is a 12V fan, you could do it with the temp controller and an old 12V cell phone power supply.
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Offline euge

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Re: Temp control for fridge/freezer
« Reply #10 on: April 05, 2012, 11:36:08 AM »
Some older refridgerators work by cooling the freezer air, then using a fan to circulate that air down into the refrigerator. A thermostat turns the fan on when the bottom needs more cold air.

Nearly all fridge/freezer combos operate this way. Not sure about a side-by-side though I can check in a few days. Might be able to get two upright side-by-side for free soon.
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Offline mainebrewer

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Re: Temp control for fridge/freezer
« Reply #11 on: April 05, 2012, 11:58:18 AM »
When I set up my fridge with temp control, I set both the freezer and fridge temp controls to max cold. The external temp controller will control the actual temp inside the fridge.
So, as noted earlier, the cold air usually originates in the freezer. As a result, the  temp in the freezer will be approx the same as the setting on the external temp controller.
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Offline heavyeng

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Re: Temp control for fridge/freezer
« Reply #12 on: April 05, 2012, 06:33:35 PM »
I wrap the carboy with an ace bandage and put the temp control probe on one side and the external thermometer on the other. Works like a champ!
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