Commercial Fridge Fermentation Chamber

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autobaun70

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My last fermentation chamber died shortly after my last brew (September), and I really haven't had the time to get around to replacing it (or brew). This week I finally got around to it, and found a nice commercial Frigidaire unit at a local used appliance shop. $350.00 and I was out the door. It was pretty nasty, but nothing Clorox Cleanup couldn't handle.

As soon as I got it home, I ripped apart my old temp control box, and dug out the STC-1000 (ebay aquarium controller) that I was using in it. Fortunately the design on the new fridge allowed for a very easy installation, and plenty of power was already available at the factory thermostat to run the controller, and the small space heater that I use to maintain temps during the colder months.

The following pics outline the build.

Exterior.......has a few dents, dings and scratches, but it will work. I will work on getting rid of all of the tape and adhesive residue another day.

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Not sure how old this price tag is, but I am glad that I didn't pay this much for it........$350.00 was plenty.

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Interior prior to adding my temp controller.

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The entire control panel drops down by removing 8 screws. Even the screws are stainless, which I found to be a very nice touch.

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In this photo you can see the factory thermostat. The top cream colored wire (looks white in this photo) is the trigger for the compressor relay. The lower terminal (blue wires) is constant 120V, which feeds power to the thermostat and the circulation fan that blows over the coils. In factory configuration, the fan is designed to run all the time, right over the cooling coils. I pulled the power for the controller and the auxiliary heat outlet from here. Because I am going to be using a space heater that has is own fan, I changed this up so that the fan only runs when the compressor is. Another benefit, because the fan is not running, it frees up a bit of amperage to run the small (200 watt) space heater. The green wire is the ground.....which I was able to make use of later.

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Same wires as mentioned above, and the hole for the STC-1000 is cut.

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I picked up a single outlet from Home Depot on the way home. If I were to do it again, I would probably go with a Decora, just becuase the cut out is easier with a Dremmel. My though was that I wanted to avoid the opportunity for more than one item to be plugged in there, just in case, and I thought I had a hole saw that was close to the correct size........but as it turns out, all of my hole saws are at my folks lake house over an hour away. Oh well, a Miller Lite 16oz aluminum bottle top makes for a perfect template (flame away about the Miller Lite). Too bad my free hand work with the Dremmel looks like someone hacked at it with an axe.......oh well, it will be out of site unless you look really close. I made one other mistake here. The bulb for the fridge was going to be in the way of the outlet, because I wasn't paying attention to how long it was when I cut the hole. Thankfully, it wasn't a big deal, just pointed the bulb holder in the other direction and all is well. I hooked the ground wire that was previously hooked to the factory thermostat to the outlet. The space heater I currently use is only 2 prong, but that is bound to change at some point. I didn't want to have to open everything back up if I didn't need to.

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Here you can see the outlet, re-positioned bulb holder, circulation fan, and the temp probe for the STC-1000. I put a grommet in the hole for the temp probe to prevent the wire from chaffing, and knotted the wire inside the control panel to be sure that it couldn't be pulled out by accident.

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Most of the way back together. The knob for the factory thermostat is still there, but does not function in any way. I plan to stick a degrees C to degrees F chart on this panel, directly below the STC-1000. A nice feature of the fridge is that it has a analog thermostat on the control panel (far right), which is independent of the control thermostat. I plan to tape the probe for the STC-1000 to the side of my fermenter when I have an active fermentation going, and stick it in jar of water if I am just using the fridge as a fridge. This extra thermostat will let me see the variance between the air temp and liquid temp.

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All back together, and a couple of the shelves installed. The shelves are one item that drew me to this unit. They are super strong. I can fit (4) 5 gallon fermenters for certain, I am pretty sure that with careful placement, 6 should not be a problem. Also, there is plenty of interior space should I ever move to a conical.

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At this point the only real setback of the project occurred. I plugged in my space heater to test everything out, and nothing. The lighted switch on the heater would come on, but the element and fan would not. Tested it in the house on a wall outlet, and sure enough it was dead. Off to wally world I went. Grabbed a 12pk of Torpedo while I was there......no need to waste a trip.

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Final item of the night was to give all of the shelves a good soak in oxyclean and bleach. They were pretty nasty as well, and are now drying in the tub.

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I hope to post a couple more tomorrow with a 10 gallon batch of my house pale fermenting away.
 
Ran into another slight issue today, which prevented my scheduled brew day from happening. The fridge is 2" too tall to fit under the shelves in my garage where I had planned to put it. Oh well, nothing a skill saw and a bit of lumber won't take care of.
 
Looks good! Might want to see if you can remove the feet and you might get enough extra clearance to fit it under the counter. I added wheels to my fermentation chambers so I can roll them in and out when needed to clean under them. I found some 5" casters on eBay for $7.00 a piece that screws right into the threaded holes the factory feet screwed into. They were 1/2", 13 threads that are pretty standard in commercial equipment. If your cutting the counter anyway might want to accommodate some wheels. Just a thought.
 
MaxOut said:
Looks good! Might want to see if you can remove the feet and you might get enough extra clearance to fit it under the counter. I added wheels to my fermentation chambers so I can roll them in and out when needed to clean under them. I found some 5" casters on eBay for $7.00 a piece that screws right into the threaded holes the factory feet screwed into. They were 1/2", 13 threads that are pretty standard in commercial equipment. If your cutting the counter anyway might want to accommodate some wheels. Just a thought.

I looked into that, and unfortunately only gains me about 1/2 an inch. Thankfully it is just garage shelving that is built out if 2x4's and OSB, so nothing too major.
 
When I automated my commercial boxes I configured the automation to just control the compressor and evaporator fan. I leave the circulation fan running all the time to assure the temps even throughout the box. I think you will find the box is more efficient this way and why it is designed to operate this way. I also found that the heat from the circulation fan motor keeps my temps where I need them in the winter. My boxes are in an unconditioned space that can get down to 30 degrees. I designed the automation to control a heater if needed but I have never needed to heat the boxes even below 30 degrees. The fermentation itself produces allot of heat and I have found between that and the heat from the circulation fan was enough to maintain temps. These boxes are designed to be opened and closed allot but for our purpose they rarely get opened. Because of that they have larger than average refrigeration units that will tend to cycle allot if your PID parameters are too tight. Just a little hint to help in set up. Short cycling the compressor is a quick way to expedite its lifespan. Try plugging the box in with just the circulation fan running and note the start temp. I’m pretty sure you could get the box to 70 degrees without a heater as I can mine even with an ambient temp of 30 degrees.
 
MaxOut said:
When I automated my commercial boxes I configured the automation to just control the compressor and evaporator fan. I leave the circulation fan running all the time to assure the temps even throughout the box. I think you will find the box is more efficient this way and why it is designed to operate this way. I also found that the heat from the circulation fan motor keeps my temps where I need them in the winter. My boxes are in an unconditioned space that can get down to 30 degrees. I designed the automation to control a heater if needed but I have never needed to heat the boxes even below 30 degrees. The fermentation itself produces allot of heat and I have found between that and the heat from the circulation fan was enough to maintain temps. These boxes are designed to be opened and closed allot but for our purpose they rarely get opened. Because of that they have larger than average refrigeration units that will tend to cycle allot if your PID parameters are too tight. Just a little hint to help in set up. Short cycling the compressor is a quick way to expedite its lifespan. Try plugging the box in with just the circulation fan running and note the start temp. I’m pretty sure you could get the box to 70 degrees without a heater as I can mine even with an ambient temp of 30 degrees.

Hmm, this I great info. I was making the assumption that by having the fan running all the time that it may pull more cooling than needed from any residual ice left on the coils. I didn't think about the heat from the fan at all.

What parameters are you using for your controller? I am currently set up at 0.5 degrees Celsius (0.9 degrees Fahrenheit) of swing, and a 10 min compressor delay. Do you think I should bump the swing parameter up to 1 degree Celsius, or possibly a bit more?
 
Hmm, this I great info. I was making the assumption that by having the fan running all the time that it may pull more cooling than needed from any residual ice left on the coils. I didn't think about the heat from the fan at all.

What parameters are you using for your controller? I am currently set up at 0.5 degrees Celsius (0.9 degrees Fahrenheit) of swing, and a 10 min compressor delay. Do you think I should bump the swing parameter up to 1 degree Celsius, or possibly a bit more?

I use the BCS to control mine and have the differential set to 1 degree and stays within 1 degree plus or minus. So with it set at 51 degrees it will not cool until it hits 52 and shuts off at 51. Running the circulation fan will also reduce short cycling and stratification in the chamber. In the chamber I use for bucket fermenters I put the temp probe on top of the buckets and have temp strips on the bucket that confirm temp with fair accuracy. I also have an analog box temp that gives me an idea of the cooling air temp. In the chambers with my conical I have a thermo well that the thermo probe is inserted to the center of the fermenter giving me more accurate temp reading and less short cycling. If you can put the thermo probe into the fermenter you will have the best results. I think with the 10 min temp compressor delay you will be good. If it seems to run allot for short periods I would adjust the swing up one degree. It’s kind of trial and error based on how much heat your fermentation generates, capacity of you refrigeration and the ambient temp
 
.....I configured the automation to just control the compressor and evaporator fan. I leave the circulation fan running all the time to assure the temps even throughout the box. I think you will find the box is more efficient this way and why it is designed to operate this way. I also found that the heat from the circulation fan motor keeps my temps where I need them in the winter. My boxes are in an unconditioned space that can get down to 30 degrees. I designed the automation to control a heater if needed but I have never needed to heat the boxes even below 30 degrees. The fermentation itself produces allot of heat and I have found between that and the heat from the circulation fan was enough to maintain temps........
I have a TRUE GDM-10 for my fermentation chamber and have found the same results. I had spent quite a bit of time and money to install a heater but have never needed it because the 9watt circulation fan provides enough heat to maintain ale fermentation temperatures in the middle of the winter in my unheated garage.

Another positive from this is I was able to convert from an STC1000 to a single stage, farenheit version, which makes it a little simpler to operate.

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Pre-conversion
 
I just scored two True GDM-26 coke display coolers for my conicals. I'm working on automating them and custom branding them now. These units have great capacity.

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Test fitting conical
 
raouliii said:
VERY nice.

I have a GDM-10 ferm chamber & a GDM-12 corny cooler and I love them. Almost bullet proof.

I use a Hobart HQ-25 for my conditioning and soon to be serving chamber. It's a single door that holds 16 Corney kegs. I'm currently using it as a Ferm chamber but like the glass door on the GDM-26 better for the conicals :)
 
Finally got to break it in today. I changed up the wiring so that the fan runs all the time. It's hard to tell in this picture, but I can easily fit 30 gallons in it.

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