Regulating Temp in Chest Freezer Not as Easy as I Expected...

The equipment: 7cu ft. GE Chest Freezer (brand new), 2 stage Ranco Temp control, a small space heater, some duct tape, a white labs vial, some freezer pack goo and two thermometers (one digital and one dial).

So, yesterday (the first day), I set the temp control to 61F with a 2 degree diff on the freezer and a 3 degree diff. on the heater. I filled the White Labs vial with goo and duct taped it to the back wall of the chest freezer. Ran to work. I had my lady friend (kinda) monitoring things while I was at work. I got home and the display on the Ranco said it was 71F inside. Ouch. I opened it up and checked the thermometers and it was 52F. Ouch. Fermentation had stopped. Double Ouch. I took the probe out of the goo and dangled it in the center of the chest freezer and went to bed cuz I was spent. It cycled a lot, obviously cuz the fan is blowing right on it, but fermentation had restarted and it was 60F when i woke up. Then I tried the duct tape-the-probe-to-the-fermenter-with-a-piece-of-bubblewrap trick. No I didn't have the tape on the probe, it was on the bubble wrap. It still cycled too much I think cuz I don't have the right bubble wrap. Its been holding at 59F, which I'm not a fan of, so I set it at 63F with a 2 degree diff. on either side.

Now here's my new trick, I stuck the probe into the vial (got rid of the goo) and filled it on all sides with dryer lint. I would like to retain author's credit if this works and its the first time someone has tried it.

Here are the questions:
1 Should the probe be on the other side of the fermenter so the heater can't blow on it?
2 How do you fill the gaps in the rubber gasket where the cords from the heater and the probe come out of the freezer?
3 Am I stupid? Is it common to have this many problems?
4 Where are all the coils in the freezer? What are the hot zones/cold zones?
5 Should there be a blanket under the fermenter, perhaps?

Feel free to dissect my procedure and add any additional insights or anticdotes regarding my techniques/set-up

Thanks in advance

You can't tape anything to the sides of the freezer, anything that touches the sides will get cold faster then the air in the freezer. If a keg of beer touches the sides the beer will freeze even though you may have the temp set at 40 degrees.

What are you using the space heater for? The only reason you would need one is if the outside air is below freezing.

For fermentation I have found that just letting the probe hang near the fermenter and setting the differential to 4 degrees works fine. The air around the fermenter may swing 4 degrees but the thermal capacity of the fermenter keeps it steady. Just tape a digital thermometer to the side of the fermenter to check your ferm temp.

What are you using the space heater for? The only reason you would need one is if the outside air is below freezing.

Because the air temp at night drops below the desired fermentation temp. Its still getting down into the low 50's at night... is that not cause for a heater inside?

No, you are not stupid.

1. Yes, sort of. I'll explain further down.
2. I use the cord type weather strip caulk. It's similar to putty or modeling clay and it's removable. Sort of like sticking some chewing gum over the gaps and you can form it however you desire. It's also very cheap.
3. No to the first part and somewhat to the second part.
4. The evaporator coils (in chest freezers) are typically embedded in the interior walls of the freezer. The condenser coils are embedded in the outer walls of the freezer. Sometimes they are mounted on the back side of the freezer, but this is less common with newer models. The walls get cold on the inside and hot on the outside. You can feel the heat radiating from the outside walls with your hand when the compressor is running. Inside the freezer, the coldest air will be near the bottom and warmer air near the top. The difference between the two can be substantial.
5. You should not need a blanket under the fermenter.

Here are some tips.

1. Initially, only use either the cooling mode or the heating mode, not both. Once you get things stabilized in one mode or the other, then you can set up the opposite mode. This is just to get things under control at the beginning. What is the ambient temp range where the freezer is stored? This will tell you which mode to use right now.
2. I prefer to use a muffin fan (computer cooling fan) to keep the air moving in the freezer. I run mine continuously, but running it intermittently with the compressor is another option to consider.
3. I also prefer to position the controller probe directly in the air stream of the fan with the controller differential set to 6 degrees.
4. I use a separate digital thermometer with it's sensor covered with insulation (bubble foil) and held in place against the side of the fermenter with a bungee. This thermometer is a cheap min/max indoor/outdoor wired thermometer. The min max feature will tell you what the temperature swing of the fermenting beer is. The idea is that any heat radiating from the fermenter will be trapped by the insulation and the insulation will isolate the sensor from the air temperature. I set the controller based on what the thermometer reads. With some experience, you will know how much to compensate for actively fermenting beer which will generate some heat. The air temps in the freezer will fluctuate considerably, but the beer will remain very stable.
5. One very important thing to remember is to allow plenty of time for the system to stabilize whenever making changes, including the initial start up. Sometimes it can take 24 hour or longer depending on how large the changes are. The big volume of beer will only change temperature very slowly.
6. It is very difficult to cool wort down quickly when it gets too warm. When a ferment gets really rock'n it will be over with before you can get it cooled down sufficiently. The trick is to start it off on the cool side and raise the temp later if desired. You won't be able to stop the volcano fast enough once it starts in most cases. There are other ways you can cool a fermenter in these situations, but putting it in a fridge or freezer is too slow IMO. Better in a tub of ice water or something similar.

Now then, if you find that you can't keep things stable using only one mode or the other on the controller, then look into setting up the other mode. I don't have a two stage controller, but I think you need to be sure that the set points and differential settings don't interfere with each other and that you have an adequate dead band. I'd have to read the manual to be more specific.

So, that's the way I do it with some variations on my four fridges and freezers. There are a lot of varying opinions on how to best configure these freezers. The responses are likely to be all over the place. All I can say is to try a few different configurations yourself and make up your own mind which might be the best fit for you.

Oh yeah, don't tape either probe to the interior wall of the freezer. That's where the cooling coils are located. The compressor will shut off prematurely and cycle too much.

coldrice said:

What are you using the space heater for? The only reason you would need one is if the outside air is below freezing.

Because the air temp at night drops below the desired fermentation temp. Its still getting down into the low 50's at night... is that not cause for a heater inside?

Click to expand...

Yes, but not a 1500 watt space heater for 7 cubic feet!

All you need is a 60 watt light bulb to produce a bit of heat. Not 2,000 BTU's

malkore said:

Yes, but not a 1500 watt space heater for 7 cubic feet!

All you need is a 60 watt light bulb to produce a bit of heat. Not 2,000 BTU's

Click to expand...

+1 I think he could get by with a very small heat source, even a 40 watt bulb would probably do it. More than likely, no cooling will be required at all right now.

malkore said:

Yes, but not a 1500 watt space heater for 7 cubic feet!

All you need is a 60 watt light bulb to produce a bit of heat. Not 2,000 BTU's

Click to expand...

I agree, a 60W bulb works for me even when the temps drop into the 30's and I'm using a glass door fridge...

No kiddin? Just a regular old light bulb?

i ferment in a 9 ft3 chest freezer, and use a 40 watt fermwrap for my heat source. i thought about a light bulb, but didn't trust myself to not hit and break it.

p.d.

I've got everything stabilized now. The probe is reading 63F, taped to the fermenter. Inside I have three thermometers- one dial, one digital and one floating in a pitcher of sanitizer that I (had) my blow-off tube running to. They all say 60F so I think I'm good. The beer is still fermenting so I'm thinking 63F is its true temperature. I think I'm going to do the light bulb thing. Soon enough I won't need it, but it will be good to have it. One last question, would it work to have a 2-way outlet adapter plugged into the chest freezer's plug on the ETC, and plug a small fan into that, so the fan and the chest freezer would come on at the same time? I wouldn't have a fan circulating the heat from the light bulb, then...

Yes, you can hook up the fan to the controller. The fan will help whether you are heating or cooling. Operate the light bulb with the controller as well.

I have a wooden collar on top of my freezer. Drilled a small hole (3/32 I think), ran some small gauge 2 conductor wire inside, sealed the hole with caulk, hooked up a small out-of-use PC 12VDC fan and powered it with a out-of-use wall-wart 5vdc power supply. On all the time, and cost next to nothing to operate.