Temp Control on a Fridge/Freezer Combo

I've done some serious searching and have not yet found an answer to this question -

If you have a fridge/freezer combo, do you require two temperature controllers? Do you disable one and remove the wall between the two cavities, so that one thermostat is controlling the whole unit? Or is it just as easy as wiring in your ranco as if it were a single cavity chest freezer?

I have a freezer top/ fridge bottom unit I'm planning to use both for fermenting ale and bottle conditioning, as it's way hot in NM and I don't want to pay for AC in an uninsulated trailer just to keep my beer (and by extension, me) happy.

I know this information has to be on HBT somewhere, but I couldn't find it. Thanks for any advice or info.

Most refrigerators have the evaporator coils in the freezer compartment only. A fan controlled by a thermostat moves air between the freezer and the fridge compartment. So, there is no way to utilize two controllers. More than likely the freezer compartment will be more or less useless. The exception might be if you are lagering in the fridge compartment. In that case the freezer will actually reach freezing temperatures and you could maybe freeze water bottles as I do and use them for cooling a tub of water with a fermenter in it. If you maintain the refridgerator at much warmer temperatures of say 65F or so for fermenting, then the freezer compartment will not get anywhere close to freezing temps. This will all vary considerably with different refrigerator models and manufacturers, but generally the above will apply to most of them.

What Catt22 said...

The freezer on my ferm fridge is fairly useless except as a storage compartment.

EXCEPT in the dead of summer. The fridge is in the hot garage and runs often enough at this time of year that I can freeze things in the freezer.

Ok, thanks for the info. Here's the plan:

Ferment 2 carboys in the bottom of the fridge at ale temps, so around 60-70 depending on what we're brewing. That takes up most of the fridge space, leaving space above for ~50 bottles (1 batch, we don't keg) above the fermenters in the fridge to prime. So in this configuration, the freezer compartment will be cooler than the fridge compartment, but not freezing.

However, all I want to be able to do is keep bottles in the freezer, either to keep cold for drinking or "cellar temp" for priming, so I the freezer is useful to me if the T range is ~40-70. I'm getting the impression that I'll have the ability to either chill or "cellar" in that compartment depending on the efficiency and design of the fridge. Does that make sense?

In summary, the fridge will be maintained at top-ferment temps via the controller, so the freezer will be cooler than the fridge but not freezing. The freezer T will be a function of the external temperature, the desired fridge temp, and the fridge/freezer interaction as designed by the manufacturer. As such, the freezer will not be directly controlled as the fridge compartment will be. Thus, the fridge will be at constant T and the freezer will be at some seasonally fluctuating cooler temperature. Correct?

Lastly, issues of finding the coolant lines and wiring aside, I can just remove that wall that separates the two compartments and they should maintain roughly the same temperature - correct?

I installed a Johnson Control on my fridge/freezer combo a couple of weeks ago. I set the Johnson to 60F and turned the fridge and freezer thermostats to the lowest temp settings. My beer is fermenting perfectly and my freezer still freezes. As a matter of fact, I put a couple cans of beer in it thinking it would not freeze and they exploded. Just my $.02.

chs9 said:

However, all I want to be able to do is keep bottles in there, either to keep cold for drinking or "cellar temp" for priming, so I can use the freezer if the T range is ~40-70. I'm getting the impression that I'll have the ability to do one or the other, depending on the efficiency and design of the fridge. Does that make sense?

In summary, the fridge will be at top ferment temps, so the freezer will be cooler but not freezing. Correct? Or am I mixed up?

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The only issue I see is that, typically, people keep bottles at 70*F or slightly warmer when bottle conditioning. If you store your primed bottles at something like 55*F, they will take a long time to carb (or might never carb at all).

Now, if the beer is already carbed and you just want to store them at a temp slightly cooler than your ferm temps, then the freezer is a fine place to put them..... just be careful that the temp doesn't get low enough to freeze things.

I went round and round trying to think of a way to use my freezer compartment on the ferm fridge, but after a full change of all seasons and seeing what happened to the freezer, it seemed pretty difficult declare an official use for it.

In the summer, I keep some grains, hops, etc in there because the freezer actually freezes. In the fall/spring, the temp in there is about the same as the temp in the main fridge compartment (good for bottle priming I suppose). In the winter, the freezer comparment is warmer than the fridge compartment because it gets cold enough in my garage that I have to use a thermostat controlled heater inside the fridge to maintain warm enough ferm temps.

Walker, you've got good points all around. I didn't expect that the seasonal variation could be so large, but seeing as our house is around 100 in the summer and 60 in the winter, the freezer will go from freezing in the summer to off in the winter.

That leads me to plan B - remove the wall between the compartments. That way, the whole unit is usable for priming/aging/fermentation between 60 and 70 year round.

chs9 said:

Walker, you've got good points all around. I didn't expect that the seasonal variation could be so large, but seeing as our house is around 100 in the summer and 60 in the winter, the freezer will go from freezing in the summer to off in the winter.

That leads me to plan B - remove the wall between the compartments. That way, the whole unit is usable for priming/aging/fermentation between 60 and 70 year round.

Click to expand...

I think your plan to remove the partition will work if you can avoid damaging the evaporator in the process. I have a small dorm size fridge that had a freezer compartment withing the refrigerator section. I simply removed the door to the freezer thingy and placed a muffin fan where the ice cube trays used to sit. It works quite well.

Revised plan -

My roommate, who is much more electronically capable than I, thinks he can throw a chip in there and connect it to some thermistors etc and the fan to control the compartments separately in our desired T ranges. We'll get to work this weekend. If it works, a guide will be made. If not, that wall still might be coming out.

Rots a ruck with that plan. I do hope it works out for you, but I have serious doubts that it will.

I just did my ferm fridge build. I used this thread for a lot of help, HERE.

I used the Dual stage love controller with hopes that I could put the 2nd temp probe in the freezer area and some how wire the compressor on/off trigger to the second side of the controller. ( IN the above thread he uses the second side/probe for a heater). Once you find the cold controller in the fridge part of your appliance it's really very easy. Good luck

FD

Dillon, thanks for the link. I'm a little unclear - you're saying you successfully use both chambers at different temperatures? It sounds like you linked the Love to the fan that pumps air from the freezer to the fridge, correct?

You are correct I can currently only control the temp in the bottom. What I want is to control both.

I just took my freezer apart a little to see how it works. I figured that since the freezer has a knob that goes "Cold" to "Coldest" it might have some kind of control module.

I was wrong, I discovered a 1/4" think oval shaped baffle. When the knob is "Coldest" the oval is horizontal blocks most of the fan cover/tunnel that leads to the bottom. When the knob is "Cold" the oval is vertical and allows the fan to blow more air into the bottom. Which makes since, because the whole unit only has one cold side condenser.

So I was thinking, I can try to rig a way to get the current wiring to just control the standard fridge fan (that current cools the freezer passively), completely block that fan from the bottom and install a computer fan in the passage way down. I could use the duel stage Love with a probe in the top blowing off the condenser and the computer fan moving cold into the bottom.

Catt22 said:

Most refrigerators have the evaporator coils in the freezer compartment only. A fan controlled by a thermostat moves air between the freezer and the fridge compartment. So, there is no way to utilize two controllers. More than likely the freezer compartment will be more or less useless. The exception might be if you are lagering in the fridge compartment. In that case the freezer will actually reach freezing temperatures and you could maybe freeze water bottles as I do and use them for cooling a tub of water with a fermenter in it. If you maintain the refridgerator at much warmer temperatures of say 65F or so for fermenting, then the freezer compartment will not get anywhere close to freezing temps. This will all vary considerably with different refrigerator models and manufacturers, but generally the above will apply to most of them.

Click to expand...

If you have a fridge with one thermostat, you can still have differing temps in the freezer and fridge that you can maintain. Set the freezer to your desired temp and then hook up your temp controller so that the thermostat is in the fridge portion and the controller turns on the fan that brings the cold air into the fridge section from the freezer.

Or you can even do what I did and buy two controllers, (inkbird on amazon makes a great one for $33) and hook one up to the entire fridge itself with one controller with the thermostat in the freezer set on 40F and the other controller setup as described above and voila!

So the freezer is now a kegerator and the fridge side holds the fermenters.

Cold kegs in the freezer, fermenters in the fridge. BAM!

Surfer446 said:

If you have a fridge with one thermostat, you can still have differing temps in the freezer and fridge that you can maintain. Set the freezer to your desired temp and then hook up your temp controller so that the thermostat is in the fridge portion and the controller turns on the fan that brings the cold air into the fridge section from the freezer.

Or you can even do what I did and buy two controllers, (inkbird on amazon makes a great one for $33) and hook one up to the entire fridge itself with one controller with the thermostat in the freezer set on 40F and the other controller setup as described above and voila!

So the freezer is now a kegerator and the fridge side holds the fermenters.

Cold kegs in the freezer, fermenters in the fridge. BAM!

View attachment 381964

Click to expand...

I'm currently thinking about doing this with my refrigerator as well?
With the above set-up, is this a freezer over fridge, single appliance? Or is the freezer a seperate appliance, next to the fridge? How do you fit a keg into the freezer section, if this is one appliance? It's too small, isn't it? Just curious and wondering if I'm misunderstanding this description?
Cheers!
Rock

Maybe I've oversimplified this in my mind. Why not use one Inkbird temp controller to control the compressor for freezer temp and another to control the fan for the fridge?

If the fridge gets warm it will blow cold air from the freezer, warming the freezer and turning on the compressor.

Nathan Graen said:

Maybe I've oversimplified this in my mind. Why not use one Inkbird temp controller to control the compressor for freezer temp and another to control the fan for the fridge?

If the fridge gets warm it will blow cold air from the freezer, warming the freezer and turning on the compressor.

Click to expand...

I think I've seen on here where guys have done that very thing. In fact, I've seen where guys install another fan with a clothes dryer flapper vent between the compartments on a side by side unit. One controller runs freezer compressor, the other turns on the fan to cool the fridge side fermentation chamber. I would love to build one someday.