Building the Beast

Building The Beast

I am a long time homebrewer and have always strived to produce the very best product that I can, given the variables inherent in any hobby that involves nature and science.

One of the most difficult to control and most important to the finished product is temperature. Keeping close control of the fermentation process yields big rewards in consistency, clarity, finish and flavor profile.

I built a version of the venerable Son of Fermentation Chiller and used it successfully for many years but was never happy with it. It was a royal pain to change ice, sometimes daily, in the hot Sacramento summers and you could never leave a batch in it and go away for even a 4 day weekend. The variability and temperature swings were troublesome from a brewing standpoint and I grew weary of bending down to the ground attempting to gently lower 6 gallons of beer in a glass carboy into and out of it.

I was convinced I could do better.

I spent hours hashing over ideas with various people including The Engineer (a licensed and skilled Mechanical Engineer and brewer) and the Asperger Kid, a brewing buddy that has read and experimented with more brew-tech and methodology than even he would care to admit.

In the end, I came up with several requirements that the new fermentation chiller must have.

1. It must be self contained. Once set, it should not require any intervention to maintain temperatures for extended periods up to months at a time
2. It must accommodate the capacity that I need to my brewing schedule and if possible, enhance that schedule.
3. It must be able to maintain two separate temperature zones. One at fermentation temperatures of 50 – 70 degrees F. and one at lagering/cold conditioning temperatures of 32 – 45 degrees F.
4. Normal fermentation chores such as changing blow off reservoir fluids, monitoring Co2 production and visually checking progress should be accomplished without having to open the chamber.
5. The fermenter should be at a convenient height for the loading and unloading of full carboys, ideally with enough room to transfer directly from the fermenter eliminating the need to move full carboys more than one time.
6. It should cost less than 50 dollars to make.

A tall order you say? Read on.

I started by obtaining for free, a small “dorm fridge” from someone who was not using it. They were glad to have it gone and I was happy to have obtained one with an actual freezer compartment rather than a bar fridge, counting on its low temperature surface and higher cooling ability to assist my efforts in redesigning it for my needs. A small dorm fridge would not ordinarily be considered for a project such as this. After much consideration and consultation, a strategy of efficiency increases, insulation improvement and potentially huge cold sinks available, I could pull it off.

The difference in the project insulation on the left and the insulation in the standard fridge is striking.

I spent a couple of hours carefully dismantling it to its component parts being careful to not bend or kink any of the hoses and lines for the coils and once it was disassembled, I could see what I had to work with. The fridge was one of the larger of the dorm fridge styles and the compressor and motor seemed in good shape. Since I had confirmed that it worked perfectly, I moved forward with confidence.

I took my tentative plans to the local home supply store and after a few minutes of careful selection for weight and straightness, I returned home with 8 2X4’s for the frame. I knew I would need several more but I had a few old studs left over from a recent remodel that I would use to make up the difference.

I laid out my lines and assembled the frame, using either half-lap or rabbeted joints for strength and screws for durability. I covered the “floor” in the top and bottom sections with plywood, again left over from my remodel.

So far, I had 22 bucks into the project.

A Note on Scrounging

I am in inveterate scrounger. I look for situations and trade or scrounge for what I need. The insulation used in this project is a prime example. I was driving by a major construction project and saw the crew putting insulation on the roof. I drove into the loading area, looked for the construction manager and asked if I could grab some of his scraps. He was happy to keep the excess out of his trash and I got a truckload of 4X4 foot scraps that I have used on numerous projects. The moral of the story is; you get your bargains where you find them.

I used the aforementioned insulation to completely enclose the frame that I had now built, caulking the joints to seal the entire enclosure.

After considerable thought, I rebuilt the same general form that the pervious fridge had, including the compressor kickout. I thought about several configurations but in the end I opted for the factory look. The extra space it gave was a bonus.

From this

To this.

When I say that laying these pieces out was an exercise in geometry would be an understatement. The third hand I got from my neighbor Mark was a big help in laying out the pieces so that everything came out square. Well, for the most part anyway.

I spent another 18 dollars on 1X3 KD boards and the Asberger Kid gave me a hand assembling some doors. With a carful selection of boards and a few minutes with some basic joinery we had manufactured the doors.

I still had the dilemma of the uneven face frame surface to contend with however. I gave serious thought to rough sanding it and laminating some mahogany veneer I had laying around but in the end, my friend Mark suggested just belt sanding the whole thing and square it up that way. We spent about an hour with his 18” belt sander and a straight edge and it came out nearly perfect.

I had most of the engineering details worked out so I started the rest of the fabrication. I had long ago decided to use 2 inch PVC pipe and 12 volt computer fans (also free) for the air transfer. I placed the supply and return at opposite ends of the chamber and plumbed them through the upper and lower sections.

Supply Side

Return side

I roughed the openings in, placed my fasteners and then disassembled it all to get ready for paint. I pulled in wire that I knew I would need to run the various fans, thermostats and other hardware and installed a separate 120 volt outlet for my stir plate. I intend to make starters at the same temperatures that the beer will ferment at and there is no place better than the same cabinet!

I was torn on paint choices but in the end, my cheap side won out and I ended up using some pure white gloss that I had laying around the house. It may not have been ideal, but the price was right!

And what a difference a coat of paint makes.

It was finally starting to look like a fridge!

After considerable thought I made the door insulation recess into the door frame and the doors face frame cover it. We hung the doors first, and then custom cut each piece of insulation to fit. Once the door frame and insulation were both ready, we secured the insulation to the door with a lot of caulk and a few screws to keep it all together while it dried.

At this point I finally ran out of caulk that I had lying around, so I had to spend money again. Chalk up another $3.20 from the orange store. Total cost so far; 43 bucks.

I spent the next few days tending to the minor but important details like fan height, sealing up some iffy caulking, completing the 12 volt wiring, installing fans and general fabrication. I am somewhat detail oriented but firmly believe in the K.I.S.S. principal. I try to build things to be as simple as needed but with attention to detail as this project reflects.

In an effort to increase efficiency I mounted a hardcore PC CPU fan and heatsink to the freezer coil. The Engineer has assured me that it will have a big payback in efficiency IF I can keep ice off it. We shall see.

The cool factor alone is worth it to me.

The Kid and I knocked out the final painting over a few beers after work and it was basically ready to go. I hacked a thermostat and moved the Thermister (the part that actually senses the temperature) to the end of a 4 foot piece of wire that can be taped to your fermentation vessel for more precise temperature measurement. I knocked out a few more minor details, double checked my systems and fired it up to test. In testing, it took the lower chamber from 62 to 34 degrees in 3 hours. So far my plan is looking good but I will need some much warmer weather to do any actual testing.

I bought some foam insulation from the orange store and I put The Kid in charge of splitting the round foam into two pieces. I ran a generous bead of caulk around the edge, applied the foam gaskets we manufactured and we were good to go. The door seals are exceptional and should last for years.

The fact that the door gaskets cost only 4 bucks was a bonus.

I brewed 15 gallons of beer in celebration, put it in the fermenter (no bending over, yeah !), put a few empty kegs in the bottom and called it good. It is far too cold in my shop to need the refrigerator capability for a while, in fact I had to put a keg of hot water in the bottom chamber to keep the upper chamber at 63. When spring and summer arrive I will be able to do much more thorough testing.

In totally, I kept it below my 50 dollar budget without compromising any of the significant details.

As you can see, it has a huge capacity for both fermentation and cold conditioning.

The totals;

Out of Pocket cash - $47.00

Labor hours - Aprox. 60 between The Kid, Mark and myself.

Capacity – up to 6 carboys in fermenter, up to 9 kegs in fridge section.

The numbers;

I postponed publishing this until I had data as I knew it would be the first question anyone asked.

I decided to torture test the system by dropping the temperature as low as I could make it for the entire system empty, then again with beer in the upper half then once again with pre-cooled kegs of sanitizer in the lower half.

The results are as follows;

Test 1 – Entire system empty, Lowest air temperature achieved

Starting temp of 63, down to 42 in 36 hours

Test 2 – Lower chamber empty, Carboys in upper cooling from 63 to 52.

Cooled 13 gallons of 63 degree wort to 52 in 9 hours

Test 3 – Lower chamber with 6 kegs of sanitizer or beer at 40 degrees, upper chambers with carboys cooling from 62 to 52.

This is the test that most closely duplicates real world performance, it cooled the 62 degree wort down to 52 degrees in 6 hours.

To say I am impressed is an understatement. To take my 62 degree wort down to 52 in 6 hours in test 3 was beyond my wildest dreams. I am thrilled with my results so far and look forward to further experiments as time goes on.

Out of my original list of “must have features I have accomplished most of them,

1. It must be self contained. Once set, it should not require any intervention to maintain temperatures for extended periods up to months at a time - DONE
2. It must accommodate the capacity that I need to my brewing schedule and if possible, enhance that schedule. - DONE
3. It must be able to maintain two separate temperature zones. One at fermentation temperatures of 50 – 70 degrees F. and one at lagering/cold conditioning temperatures of 32 – 45 degrees F. - DONE
4. Normal fermentation chores such as changing blow off reservoir fluids, monitoring Co2 production and visually checking progress should be accomplished without having to open the chamber. COMING SOON
5. The fermenter should be at a convenient height for the loading and unloading of full carboys, ideally with enough room to transfer directly from the fermenter eliminating the need to move full carboys more than one time. - DONE
6. It should cost less than 50 dollars to make. - DONE

I strongly urge any serious brewer using ice based cooling systems to look into building one of their own. The freedom to be relieved of the tedious task of changing ice and the issues associated with it is a godsend. The added space for storage/lagering/carbonating is a bonus.

That being said, this was a serious bit of fabrication. I don’t think it is for a casual weekend warrior. It involved a lot of thought and imagination to come up with some of the ideas and a cheap and/or easy way to get around problems.

Comments, questions and offers of cash can be sent to knewshound@yahoo.com

Edit; I have had several questions regarding the operation of this thing. Rather than try to explain it, I have created this block diagram describing how it works. I hope this is helpful to you guys.

Edit #2 - Press Eject at Wort-O-Matic has cross posted this and I have had several Comments that I will post here also;

triple-oh_six on 03/30/09 08:28 pm writes

Nice work man, great idea!

knewshound on 04/01/09 07:38 am writes

Thanks, I appreciate the kind words.

I have since discovered that the "observation ports" or "windows" in the doors are a must have. The opening and closing of the doors to observe the fermenting brews was causing me no end of problems with icing on the freezer coil.

The only answer was to either stop opening the doors to check the fermentation progress (not a real option) or to put the windows in the doors and check it that way.

I opted for the window solution.

I will document any other changes I make as I learn more about the Beast.

These are some of the issues you have when you do something that has never been done before, lots of trial and error!

Cheers,

knewshound

Jamman on 04/11/09 07:33 pm writes

This is awesome. I may have to think about something similar. Can you separately control the temperatures on the upper and lower cabinets? How/where do you have the fans set? Could temperature control be maintained with fans on/off?

The Engineer on 04/14/09 01:28 pm writes

The upper chamber draws air from the cold box via fans, so theoretically it can have much different temperature than the lagering area. However, there is a catch. If you try to cool the top down too much, the top and bottom chambers will eventually come to the same temperature since the cooling is not sufficient to keep the entire box at 33 degrees. We going to try adding a fan to the condensor coil to up the cooling effectiveness and see what that does. Worst case: Add another dorm fridge.

Sante,
The Engineer

knewshound on 04/15/09 03:16 pm writes

Thank you Tom for the assist :)

The Engineer is entirely correct as usual.


You asked - Can you separately control the temperatures on the upper and lower cabinets?

I hacked a regular household thermostat I had lying around the shop by removing the thermistor in it and putting it on the end of a 4 foot piece of light gauge wire. I affix the thermistor to the fermenting carboy for very precise temperature control. In experiments, I have found as much as a 4 degree difference between the observed air temperature vs the carboy temperature.

You asked - How/where do you have the fans set? Could temperature control be maintained with fans on/off?

I use the existing relay built into the thermostat to switch a 12 volt power supply "wall wart" that used to power a calculator and run it to a fan I liberated from an old PC I had lying around to move the air through 2 inch PVC pipes.

Through trial and error I have discovered that having a "heat sink" of full kegs in the lower chamber is a big help in bringing 60ish wort down to 48 degree pitching temp quicker and with less effect on the temperature stability of the lagering brews in the lower chamber.

As The Engineer has said, I am going to experiment with a small fan and a hood for the condenser coil on the back to get some airflow and hopefully, a few more percentage points of efficiency.


Cheers,

knewshound

bud on 06/08/09 08:15 am writes

I don't have a dorm fridge, but I have a full sized fridge that I don't use much. Could I use a full sized fridge and if so, how would I incorporate it into your design? Thanks.

knewshound on 06/09/09 07:46 am writes

Sure you can. Obviously, the configuration would need to be changed.

Obviously, the larger the fridge, the greater the capacity and the better performance you will achieve.

If I had to do it all over again, I would start with a larger fridge from the beginning. The dorm fridge is struggling a little with the Sacramento heat. Not enough to make it too warm in the storage compartment, but the fridge is working HARD.

Since this was a custom, one off design, it is up to you for the configuration and design.

Give it a shot !

If you get it running, please lets us all know.

I for one would love to see how it turns out !!!!

bud on 06/15/09 09:18 am writes

Another question. What kind of hinges did you use for the doors? Are they spring loaded to help hold the doors shut or did you use some kind of latch? I can't tell from your pictures. Thanks.

knewshound on 06/22/09 08:44 am writes

Well, since I am cheap, I just used regular door hinges I had laying around the shop.

I thought about using Piano hinges just for the nice slick look, but as usual, I was cheap and used what I had on hand.

Since the hinges support very little weight ( the doors are really just a face frame with foam insulation ) they don't really need to be all that much.

Experiment !

Thats all I do !

fastdogbrewing on 06/23/09 11:03 am writes

I am about to start a build of a couple fermentation cabinets myself and was wondering what the insulation is, and where you got it. This is the biggest issue I am looking at right now.

I will be using modified window Air Conditioners, and my layout will be more along the line of a chest freezer.

Thanks for the inspiration.

Pleepleus on 06/24/09 05:12 pm writes

I built something similar using a converted cabinet, 1.5" foam, and mini fridge components. I completely closed in the bottom like a chest freezer though. My problem is that the compressor is running constantly. I'm able to keep the top portion at 60F for fermenting, but the bottom never will drop below 45F for adequate serving temps. The ambient temp in my basement is currently in the low to mid 70's so it shouldn't be working too hard. Currently I don't have anything in the bottom, which might be part of the problem since it's just exchanging air and has nothing else to hold the temp.

Do you, or anybody else, have suggestions on how I might make this thing more efficient?

knewshound on 06/25/09 10:37 am writes

Fast Dog - I scrounged my insulation from a construction job. I gave the foreman a couple of bombers plus a 6 pack of home brew and he couldn't give me enough insulation.

If you cannot find a source like that, you CAN use the white "open cell" foam you can get a Home Depot or Lowes as an acceptable substitute. It is not quite as efficient as the closed foam but the price is right :).


Pleepleus - I have the very same issue actually. With the chamber empty, no kegs inside, it rarely gets below 45(ish). I attribute it to several factors.

#1 - The temps in my shop are pretty high, in the high 70's - low 80's or more. According to The Engineer, 35 - 40 degrees below ambient is about as good as I can realistically expect. Your mileage may vary of course. That being said, mine never shuts off, ever, when I have the thermostat maxed as it usually is.

One thing I have noticed is that if it does get into the 30's, it tends to stay there if there is a quantity of full kegs. I think of it as a "cold sink" rather than a "heat sink". Have you tried cold crashing some kegs in some other way, a freezer for instance, into the low 30's then throwing them into your chamber?

You might be surprised at how well that works.

Once it gets to temp, it wants to stay there.

That being said, if you are trying to do the air recirculation for fermenting, you will have a very difficult time keeping the lower half at serving temps. It is just too much a load for the fridge in Summer.

Most of my baseline tests were done in cold weather, when I do most of my brewing. I use the chamber for storage only during the summer and just don't brew in summer.

This was a specialty build to suit myself and how I brew. Using the chamber to both serve and ferment, in the summer, may simply be more than the equipment can provide. I suspect that you would need an actual freezer with its higher capacity to use it year round.

I have asked The Engineer to respond for a more informed opinion for you.

Cheers,

knewshound

The Engineer on 06/25/09 11:36 am writes

Pleepleus: There are only a few factors that can effect the run times. Heat transfer and moisture being the top two.

If the box is sealed well and is well insulated, you may want to look at the other factor of the heat transfere: The Condensor Coil.

If it is tucked away and the natural convection currents that it relies on to do the cooling are being restricted in any way, it will reduce the cooling capacity of the unit. Just for a simple test, place a small fan directed at the cooling coils to see if that helps.

In the end however, we have to be realistic. The small fridge that it came out of was designed to run 20% of the time at 70 degree room temp with a small water vapor leakage factor. We just quadrupled (or 6x for the knewshound) the size of the box and made it much more leaky. In a perfect world it would run 80% of the time and with the vapor leakage and such, 100% is not unexpected.

Pleepleus on 06/26/09 08:46 pm writes

Thanks to both for the responses. I don't have any cornies yet, but adding some gallon jugs of water and a case+ of beer did help some with maintaining temp around 50 so the compressor didn't run constantly. It still didn't drop to where I wanted at the setting I had though. When I cranked it up a little more it went back to it's constant run.

The condenser coil doesn't have a ton of breathing room (maybe a couple inches) and I already have a fan blowing on it. However, I think it's getting more air than it did when it was in the fridge. The fridge I acquired didn't have the same sort of coils knewshound's had (external), but instead had copper tubing running underneath the metal shell and was pretty well wrapped up in the foam they injected in there (talk about a bitch to get apart).

I know that I'm pushing the compressor and cooling ability to it's limits so I'm not expecting miracles, just looking for any bump in efficiency I can. It may not be realistic for me to use it for both purposes at the same time, and may have to switch back-and-forth as my needs dictate.

Thanks again.