Metzen's Mini Fridge Glycol Chiller Conversion

[Metzen]

Follow up- sucessfully hit 35*F and hit the beer with gelatin. Set the differential to 3*F so the pump kicks on at 38*F. This is pushing the limits of the system as the pump kicks on every 110 minutes or so and runs for about 12 minutes to get back to 35F, the fridge doesn't get much down time. To Rehash the numbers- thats roughly 12 gallons of beer being chilled by 10gallons of glycol at 20F.
I also suspect that the diaphragm pump is warming the glycol as I have seen less and less return below 42F. I wonder if the pump could draw through the coil rather than pushing, if that might help. Obviously better insulation and more glycol volume would also improve my results.

Very cool and glad to hear this is working well for you. Looks like a great setup.

As noted in my original post, we have another little one on the way and I haven’t been able to brew this winter. I’ll post an update soon on some minor changes to my system and answer some of the questions that have been asked here.

Cheers

 

[Metzen]

Follow up- sucessfully hit 35*F and hit the beer with gelatin. Set the differential to 3*F so the pump kicks on at 38*F. This is pushing the limits of the system as the pump kicks on every 110 minutes or so and runs for about 12 minutes to get back to 35F, the fridge doesn't get much down time. To Rehash the numbers- thats roughly 12 gallons of beer being chilled by 10gallons of glycol at 20F.
I also suspect that the diaphragm pump is warming the glycol as I have seen less and less return below 42F. I wonder if the pump could draw through the coil rather than pushing, if that might help. Obviously better insulation and more glycol volume would also improve my results.

Very cool and glad to hear this is working well for you. Looks like a great setup.

As noted in my original post, we have another little one on the way and I haven’t been able to brew this winter. I’ll post an update soon on some minor changes to my system and answer some of the questions that have been asked here.

Cheers

 

[tikoziko]

Hi all, thanks so much for the info in the thread, I've copied the design and am in the middle of my first fermentation, all is going pretty well so far, 15 litres of solution (5L of glycol and 10L of water) for 22L of wort.

See a pic of my setup:

 

[tikoziko]

The only issue I've hit so far is that the temperature probe for the fridge controller is reporting big jumps in temperature quite randomly, it can jump up or down 2 or 3 degrees sometimes. I simply popped the probe into the glycol solution when setting things up, I wonder if it's wandering around a bit and the stratification of temps inside the reservoir is producing the big jumps in temp?

Can anyone suggest a good place to stick the probe? Right down in the corner of the container maybe? if so how to stick it there as some tape would get wet and fall off. Or near the surface perhaps, but as far away from the submerged freezer compartment?

Cheers

 

[tjpfeister]

So that's a freezer chilling your glycol via air?

 

[tikoziko]

It's almost exactly the "Metzen setup", 15L of solution sitting inside a plastic container with about a third to a half of a bent freezer compartment submerged to do direct cooling.

 

[tikoziko]

the cooling unit is a fridge/freezer a la Metzen's spec, just a slightly larger model.

 

[Bigs166]

Very cool and glad to hear this is working well for you. Looks like a great setup.

As noted in my original post, we have another little one on the way and I haven’t been able to brew this winter. I’ll post an update soon on some minor changes to my system and answer some of the questions that have been asked here.

Cheers

Awesome build. I’m sick of loading ice and bottles. I take it you’ve had a lot more experience using the system since the beginning of the thread. Would you still recommend the system? What would you change? Get one with the largest (or larger) “bendable” metal freezer cooling thing in it? Any other pointers before I start gathering materials?
Thanks s lot!

 

[Bigs166]

Hi all, thanks so much for the info in the thread, I've copied the design and am in the middle of my first fermentation, all is going pretty well so far, 15 litres of solution (5L of glycol and 10L of water) for 22L of wort.

See a pic of my setup:
View attachment 567134

Awesome build dude! I am gathering materials for my build here in the next week or so. Can you post some interior pics? Anything you would change? Pointers?

Thanks!

 

[Metzen]

Awesome build. I’m sick of loading ice and bottles. I take it you’ve had a lot more experience using the system since the beginning of the thread. Would you still recommend the system? What would you change? Get one with the largest (or larger) “bendable” metal freezer cooling thing in it? Any other pointers before I start gathering materials?
Thanks s lot!

I would definitely recommend it for smaller batch sizes as described earlier in the thread. It's still working well just as it did when it was built. I've run about 8 batches through it since I started this thread.

The hardest piece to obtain was a glycol reservoir large enough to fit the coils that didn't have handles or pitched side walls. You want something with walls as close to 90 degrees as possible as you want the coils to go as far down as they can and you also need to slip the reservoir behind the coils and the side wall (the coolant line usually connects to the wall or top of the fridge near the wall). I bought a couple containers initially that wouldn't fit well. Even the one I ended up with only allows the coils to go down about halfway before it is pinched between the sidewalls that narrow at the bottom.

This is where it sits today (under the bags of grain). I must say I am super pleased with how it looks aesthetically (just a black box) vs some of the other DIY solutions.

Hope yours turns out well. Please do share any other tips or tricks you uncover during the build.

M

 

[SanPancho]

@tjpfeister Youve got too much glycol in there. A typical mix is about 1\3 glycol. Glycol has less heat transfer than water, you only want as much as needed to prevent freezing. Working the unit too hard.

If your goal temp is 38, youll want the coolant at 25-28, and that means your glycol mix should freeze 10~15 below that, say 10F. There are calculators online to give the proper ratio. In this setup better to start with less glycol and be on the lookout for ice on the evap since its easy to see. You can always add more glycol easily.

You should also have your pump sitting behind the evap to pull the coldest mix and the hot return dumping on the opposite side. That way the flow is generally towards and thru the evap to promote good mixing and cooling. Didnt see those details so just throwing that out there.

Definitely interested in seeing a thread on your build too.

Thanks @Metzen for tip-off on this thread. Exactly what i was thinking of building myself.

Also, i dont have the link but somebody started a thread a few weeks back about using plastic hose to wrap their fermenters and had good results. For those that dont want to deal with copper or stainless tubing its a cheap and easy way to get the glycol onto your fermenter.

 

[Metzen]

My setup uses 1/3 glycol and the rest distilled water. Agree you should limit the glycol.

 

[Bigs166]

I would definitely recommend it for smaller batch sizes as described earlier in the thread. It's still working well just as it did when it was built. I've run about 8 batches through it since I started this thread.

The hardest piece to obtain was a glycol reservoir large enough to fit the coils that didn't have handles or pitched side walls. You want something with walls as close to 90 degrees as possible as you want the coils to go as far down as they can and you also need to slip the reservoir behind the coils and the side wall (the coolant line usually connects to the wall or top of the fridge near the wall). I bought a couple containers initially that wouldn't fit well. Even the one I ended up with only allows the coils to go down about halfway before it is pinched between the sidewalls that narrow at the bottom.

This is where it sits today (under the bags of grain). I must say I am super pleased with how it looks aesthetically (just a black box) vs some of the other DIY solutions.

Hope yours turns out well. Please do share any other tips or tricks you uncover during the build.

M
View attachment 577476

Thanks a lot. So do you just let the fridge run normally? No temp control probe in the glycol? I’m prob only going to use it for fermentation (60-70 degrees).

 

[Metzen]

Thanks a lot. So do you just let the fridge run normally? No temp control probe in the glycol? I’m prob only going to use it for fermentation (60-70 degrees).

I built a controller using the CraftBeerPi software to control the temp of the glycol solution and the fermenter. I have a temp probe in the glycol bath. I run the wire of the probe through a slit in the rubber door threshold.

I set the glycol temp to 12 degrees below the target temp of my fermenter (glycol to 55 degrees if target fermentation temp is 67).

 

[Metzen]

Also, I set the analog thermostat of the fridge to its coldest setting. The controller turns the fridge on or off to maintain the set temperature of the glycol solution. My controller has a delay feature to reduce the cycling of the fridge's compressor on and off (ie it makes sure the fridge is off for at least 10 minutes before turning it back on). So usually the glycol will be anywhere from 10-15 degrees less than the fermenter target temp which is perfectly fine.

 

[Bigs166]

Also, I set the analog thermostat of the fridge to its coldest setting. The controller turns the fridge on or off to maintain the set temperature of the glycol solution. My controller has a delay feature to reduce the cycling of the fridge's compressor on and off (ie it makes sure the fridge is off for at least 10 minutes before turning it back on). So usually the glycol will be anywhere from 10-15 degrees less than the fermenter target temp which is perfectly fine.

Did you remove the thermostat wire that is connected to the freezer part? Mine has a small white cord attached to it. What did you do with this part? Leave it dangle?

 

[Metzen]

Did you remove the thermostat wire that is connected to the freezer part? Mine has a small white cord attached to it. What did you do with this part? Leave it dangle?

It was attached to the freezer coil by a metal clip. I just left it clipped as is, but it doesn’t go into the glycol solution where it’s positioned.

 

[Bigs166]

It was attached to the freezer coil by a metal clip. I just left it clipped as is, but it doesn’t go into the glycol solution where it’s positioned.

Ok. I’m running two pond pumps on two different fermenters. Does it take the fridge a long time of cycling on and off to completely chill look like hall down all the way? I’m just using the fridges stock thermostat. The glycol is at 64°. And slowly going down. It will eventually get down right??

 

[Bigs166]

I threw a couple ice packs in there just to give it a head start

 

[Bigs166]

It was attached to the freezer coil by a metal clip. I just left it clipped as is, but it doesn’t go into the glycol solution where it’s positioned.

Metzen,
Just wanted to say thanks again for creating this whole thread. The build was so easy and it works like a charm. Glycol stays between 23-25 degrees. I think I’m going to try and lager with this thing! By the way: The container store was ideal for finding the perfect container for the tank.

 

[Bigs166]

I would say it works extremely well actually. (Probe submerged in glycol mix)

 

[jturman35]

I may have missed in the thread but how does this work in a garage with where the temps could reach 90 degrees. Can a small mini fridge keep a 5.5gallom batch 62-68degrees?

 

[Metzen]

I may have missed in the thread but how does this work in a garage with where the temps could reach 90 degrees. Can a small mini fridge keep a 5.5gallom batch 62-68degrees?

I have no doubt that this can keep a batch at ale fermentation temps at that ambient temp. You may struggle to keep at lagering or crash chilling temps, but ale fermentation temps won’t be an issue.

 

[jturman35]

Does the condensation cause an issue? I can’t imagine this conical not sweating to death in the MS humidity.

 

[GParkins]

I have a question and an observation. My question is for the OP... @Metzen, how have you dealt with condensation forming on the outside of your glycol reservoir?

I may be able to help answer @jturman35 about garages. I'm in South Florida, my garage door faces South, and my chiller is about 3' away from the door. Not sure if it could get any hotter or muggier in the middle of the summer. Right now, I have 15 gallons of beer spread across two 60-liter Speidel fermenters in a DIY 30 cu ft. ferm chamber, and my compressor is kicking in once every three hours to maintain the beer at 65℉ during a diacetyl rest. In a couple of days, I start lowering the temp to lager range, so I expect it will start cycling more. The more you insulate the reservoir, fermenters, and hoses from ambient air, the less effect the ambient conditions will have on your system.

My observation is one I didn't expect: My reservoir has been filling itself up. It turns out that propylene glycol is hygroscopic, and it has been drinking in moisture from the ambient air. Lots of moisture.

When I started looking into it, I found out that most commercial glycol systems are closed loop, preventing contamination from ambient air. I guess what I need to do is figure out how to seal off the reservoir from the rest of the world.

 

[SanPancho]

I would say it works extremely well actually. (Probe submerged in glycol mix)

View attachment 581856

Thats just a small dorm style fridge right? The half size ones?

 

[Metzen]

I havent sealed the reservoir but also havent experienced any issues with excessive condensation. I have had some condensation just from the temp swings and the frost on the fittings inside the fridge melting. However, I usually give the inside of the fridge a quick wipe with a paper towel between each brew and its clean.

I havent had any issues with the reservoir overflowing or anything, so maybe having the fridge kept closed keeps the ambient air humidity to a minimum?

 

[user 232000]

HI Mertzen,

First thank you and all for posting this great information. I have been looking for weeks and finally came across your thread, and finally found others that have experimented using existing fridges to control the glycol. I have an open question, and would like anyone's input, no matter the idea, to help me. I am thinking to use the glycol to cool down my kegs to serving temp. I can make or buy a cool zone jacket for gylcol, but I want to cool down the glycol differently. I want to place a glycol reservoir in my Fermenator 3 freezer section, my all in one (2 x conical fermentor/keeger/freezer) hack. I digitally control all 4 zones including the feezer, and what I would like to do is have an open reservoir in the freezer section and a closed loop stainless tube, maybe coil like, immersed in the reservoir, then pump it thru the cooling jacket (2 kegs at different temperatures using control valves). So as your design moves the glycol outside the dedicated fridge, I want to use the cooling I already have inside the freezer section just waiting for me to tap into. At this point I am guessing my glycol will be around 8-12 degrees out of the reservoir. My freezer keeps at a constant 0 to 2 degrees , but I can go up or down a little (-5 or so) as needed.


So my question is, if the temp differential between the beer temp and the glycol temp is 12-15 degrees, in place of trying to change the glycol temp continually, would it make seance to turn on/off the pump for each keg via temp control? if I am pumping 15-20 degree glycol around the kegs, based on what you know, if I pumped it until the temp hits is set point, the shut it off, and then back on after it drops to X, would the be an efficient way to do it, or do you see any holes in my "theory".

I can keep the kegs now at about 48 degrees constant, but to get them to 36 for lagers/pils, or even 38 for ales, i am running my compressor for hours and as soon as I open the doors, I have to start all over. This is not normal, but due to my all in one design, everything inside the one refrigerator. My two goals are to be able to efficiently keep the kegs cool, and # 2 each having different temps. I have BruControl software and an Arduino , so the control part is easy, the "theory" , not so much. It seems if this works, then I will have a small 12v pump on and off verses my compressor on and off constantly, and then be able to also have each keg at its own temp, sitting next to each other. And in South Florida, I can not tell you how hard these things have to work in 90+degrees heat and 90% humidity in our summer, which is of course just about all year round.

Again, thank you to the trail blazers like Metzen for your time and help, all of us appreciate it.

KDAZ

 

[user 232000]

sorry Metzen, I typo-ed your name wrong, my bad.

 

[milldoggy]

I have a question and an observation. My question is for the OP... @Metzen, how have you dealt with condensation forming on the outside of your glycol reservoir?

I may be able to help answer @jturman35 about garages. I'm in South Florida, my garage door faces South, and my chiller is about 3' away from the door. Not sure if it could get any hotter or muggier in the middle of the summer. Right now, I have 15 gallons of beer spread across two 60-liter Speidel fermenters in a DIY 30 cu ft. ferm chamber, and my compressor is kicking in once every three hours to maintain the beer at 65℉ during a diacetyl rest. In a couple of days, I start lowering the temp to lager range, so I expect it will start cycling more. The more you insulate the reservoir, fermenters, and hoses from ambient air, the less effect the ambient conditions will have on your system.

My observation is one I didn't expect: My reservoir has been filling itself up. It turns out that propylene glycol is hygroscopic, and it has been drinking in moisture from the ambient air. Lots of moisture.

When I started looking into it, I found out that most commercial glycol systems are closed loop, preventing contamination from ambient air. I guess what I need to do is figure out how to seal off the reservoir from the rest of the world.

Good info. I awoke to my chiller overflowing after 2.5 years of running. It gained about .5 to 1 gallon in that time frame. Freaked me out for a bit.

 

[Beerwildered]

I'm transitioning from a fermentation chamber to a glycol cooling system using a converted mini fridge with a freezer compartment as a chill source. I had read a few comments on this approach on these forums but nothing that provided much detail on build or examples. I'll keep this thread updated as I test my first brew and make observations.

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View attachment 406821

My ferm chamber worked perfectly fine, but let's start with a few key reasons for the transition to glycol:

1) Wanting to ferment more than one batch at different temps at the same time (i.e. Ferment, cold crash, or lager different batches at the same time)
2) Lack of space in my "brewery" (term used very loosely) and unwillingness to buy multiple fridges to handle more than one vessel

So a glycol based solution was appealing. However, I only brew small batches (usually 5 gal, rarely 10 gal) and spending $1k or more for a chiller would never get approved by the Mrs.

I considered a few DIY options:

(i) AC unit conversion - documented in depth across this forum - seemed a bit clunky and wouldn't fit well in the closet (see photo above) in which I planned to keep my fermenters. I also planned to stack Brew Buckets and this wouldn't have been an a very sturdy base for this
(ii) Chest freezer with glycol reservoir - never liked the idea of relying on air or surface contact between a freezer and the reservoir as a heat transfer medium
(iii) Water chiller or aquarium chiller - concerned that they wouldn't provide enough cooling to lager or crash chill
(iv) Mini fridge, immersing the freezer compartment in the glycol/water solution - decided to go this route (more info on how it works below)

The benefits of the mini fridge are:
(a) self-contained chiller that I could store in a living space if needed (with a decent mini fridge and blingy vessel to sit on top, you can turn this into a conversation piece IMHO)
(b) can stack my ss brewtech buckets on top of fridge
(c) super cheap as the mini fridge cost me $60 with incremental cost of an ink bird temp controller, barb fittings, a container to hold the glycol, etc. All in was about $120 excluding the BrewBucket cost and accessories given these items are required regardless of the type of chiller

Basic components/concept of this system (for those less familiar with glycol chilling):
- The freezer compartment of the mini fridge cools the glycol by being immersed directly in the glycol reservoir and solution
- Ink bird or other temp controller reads the temperature of the glycol and turns the fridge on and off to keep the glycol at a set temp (this is independent of the fermentation controller that will control your fermentation temperature, see below)
- Your fermenter will need an immersion coil, a glycol or cooling jacket, or some other way of getting the chilled glycol running through or around the wort to cool it down. I use the ss brewtech FTSs for my brew bucket that has an immersion coil dropped from the fermenter lid into the wort.
- You will need a fermentation controller (I am using the SS brewtech FTSs that goes with my brew bucket, but any is fine) that reads the temp of your fermenting beer and toggles a pump on and off that sends the chilled glycol to the immersion coil, cooling jacket, etc. when the fermenting wort needs to be cooled. The pump sits in the glycol reservoir in the mini fridge and sends the glycol through tubing running out of the fridge to to the fermenter.

Parts for my build:
- Haier 2.7cf fridge (HC27SG42RB) (bought an open box with minor external damage during a sale - $60)
- Polycarbonate container (to be used as glycol reservoir) rated for freezing temps with a minimum 9.5" width, max 12" height, max 12" length
- Ink bird or other temp controller
- 2 x 1.5" 1/4 MIP nipple fitting
- 3 x 3/8" barb to 1/4 MIP fitting
- 3 x 1/4 FIP to 1/4 FIP elbow fitting
- 1 x 1/4 FIP to 3/8 MIP fitting
- 1 x 3/8 barb to 3/8 FIP fitting
- 3/8 ID 1/2 OD vinyl tubing
- 4+ clamps to secure tubing to barbs
- optional but recommended: quick disconnects for tubing (on order for my setup)
- 4 x 7/16" ID neoprene washer
- 4 x 5/8" ID metal washer

DISCLAIMER: FOLLOWING THE BELOW WILL VOID ANY WARRANTY ON YOUR FRIDGE. I ALSO HAVE ONLY TRIED THIS AND AM STILL TESTING ON MY OWN FRIDGE. I'M NO PRO AND HOLD NO RESPONSIBILITY IF YOU BREAK THE FRIDGE, SPRAY GLYCOL EVERYWHERE, DAMAGE SOMETHING ELSE IN THE PROCESS, OR THIS JUST DOESN'T WORK FOR YOUR SETUP.

Build steps:
1. Unscrew and remove the plastic freezer compartment door.
2. Unscrew from the roof of the fridge one side of the freezer compartment farthest away from the coolant line (middle of the fridge in my unit, coolant line is back right corner).
3. Once freezer compartment is connected by only one side, SLOWLY and CAREFULLY bend and straighten the freezer compartment down against the side wall of the fridge. DO NOT CRIMP OR KINK ANY COOLANT LINES INCLUDING THE LINE FEEDING THE FREEZER COMPARTMENT. You can bend the compartment easily by sticking a few fingers or a cylindrical object between the bottom corner of the freezer compartment and the side wall of the fridge to use as leverage/support. Just go slow.
4. Remove the thermo probe of the fridge's thermostat from the freezer compartment (usually connected with a metal clip to the bottom of the freezer compartment)
5. Position your flattened freezer compartment into your glycol reservoir. Secure your reservoir in the fridge.
6. Drill two holes into the fridge where there are no coolant lines or other obstructions (I used the door as there is usually no obstruction there in most if not all mini fridges). I drilled 5/8" holes that fit my 1/4 MIP nipple fitting. My door was 1.25" deep (at its shallowest point in the top shelf on the door - avoid the plastic structures of the door that jut out to form shelves and can dispensers) so a 1.5" length nipple worked well.
7. Feed a 1/4 MIP 1.5" long nipple through each hole and add a neoprene and metal washer to each side (neoprene closest to the fridge to provide insulation) before attaching your barbed fittings.
8. Attach and cut vinyl tubing to length both inside the fridge to reach bottom of glycol reservoir and outside fridge to connect to fermenter.
9. Drop the pump connected to your fermentation controller (whichever you use) into the reservoir and ensure it is connected to the outlet tubing/fitting leaving through the fridge wall.
10. Fill your glycol reservoir with 33% glycol (~1 gallon) and 66% distilled water (~2 gallons) assuming your reservoir can hold 12 quarts or more. There are other posts on proper concentration of glycol you can reference.
11. Drop your ink bird or other temp controller temp probe into the bottom of the reservoir.
12. Plug the fridge into your ink bird or temp controller. I feed the ink bird wires through the top of the fridge door near the hinge.
13. Ensure the fridge's thermostat is set to a moderately cold setting (try not to overwork the compressor during the initial cooling of the glycol) and reposition the fridge's thermostat probe back into the flattened freezer compartment.
14. Set the ink bird or your temp controller to a level 15-20 degrees F below your target temp so that the glycol is chilled to 15-20 degrees below target.
15. Let the ink bird or temp controller maintain glycol temps while your fermentation controller toggled the pump on and off when cooling is needed.

My main concern with the mini fridge was whether it would provide enough cooling for lagering and crash chilling.

As a first test, I brought the glycol down to 10-15 degrees without much of an issue. The fridge was warm to the touch on both sides as expected but not overly hot. The key is not to overwork the compressor when the 3 gallons of glycol/water are first added. Ramp temps up slowly. Once you are in range, I found that the temp is maintained quite well. I was pleasantly surprised with how efficiently the mini fridge cooled. I ran an external loop of tubing between the inlet and outlet ports without insulation just to test the effect of heat loss while running the pump. The fridge and ink bird seemed to keep up just fine.

The next test is to chill 5 gallons of wort/water running through my SS Brewtech Brew Bucket. I also have a batch completing primary in my ferm chamber now. I plan to attempt a crash chill in the next couple weeks. Will report back soon.

Pending additions/changes to the system:
- Quick disconnects with valve shutoff to enable easy detachment and reattachment of glycol lines to the fermenter
- Insulation for the fittings and other areas of potential heat transfer (this is super critical when using a system not designed for glycol chilling as any heat transfer not from the wort will significantly impact efficiency)
- Door clamp/lock to ensure the fridge door doesn't pop open while in use. I have found that the vinyl tubing I use slightly straightens when cooled and puts outward pressure on the door given the lines feed through the door. I don't want it popping open unintentionally.

Would appreciate feedback or suggestions if anyone has them!!

Cheers
M

I’m about to embark on this project - I’ve got a Magic Chef 4.4 cu ft fridge and I’ve purchased all of the necessary hardware.

It’s been a couple of years since this build and I’m wondering what works well and what you might do differently?

Can you reach primary lagering temps in the 40s/50s? Lower?

What’s the largest volume of beer you’ve fermented with this?

Thanks for the inspiration!

 

[Metzen]

I’m about to embark on this project - I’ve got a Magic Chef 4.4 cu ft fridge and I’ve purchased all of the necessary hardware.

It’s been a couple of years since this build and I’m wondering what works well and what you might do differently?

Can you reach primary lagering temps in the 40s/50s? Lower?

What’s the largest volume of beer you’ve fermented with this?

Thanks for the inspiration!

I just cold crashed to 39 F last week on a 6 gallon batch. I have two 7 gallon fermenters (SSBT unitank and SSBT bucket) that I’ve controlled at the same time. You can only crash one of them at a time - maybe lager two at a time.

But overall it still works great. Good luck with the build. Kegging my latest stout below - you’ll see the fridge under the fermenter.

 

[Bigs166]

I’m about to embark on this project - I’ve got a Magic Chef 4.4 cu ft fridge and I’ve purchased all of the necessary hardware.

It’s been a couple of years since this build and I’m wondering what works well and what you might do differently?

Can you reach primary lagering temps in the 40s/50s? Lower?

What’s the largest volume of beer you’ve fermented with this?

Thanks for the inspiration!

You can see my build earlier in the thread as well. I can get mine to stabilize a full 14 gallon unitank at 42 degrees. I keep the glycol mix at 9 degrees. You can’t just drop the temp from 68 (fermentation temp) down to 42 immediately with these builds though. You need to slowly drop the temp so the fridge has a chance to catch up and re chill the glycol. I drop the beer temp 2 degrees every hour until I get it down into the 40s. It will click on and take the beer down 2 degrees within 15 mins. At the same time the glycol temp will shoot up into the 20s and as you go lower it will go into the 30s. It will take about 45, then 50, then 60, then 70 etc. minutes for the glycol to completely re-chill back to 9 degrees. the glycol temp keeps going up by needing more and more contact time to drop the beer temp lower and lower. So it needs more time to re-chill every cycle. You end up reaching a point of diminishing returns so to speak. Another thing is is that once I get around 53 degrees and lower, the fridges compressor does not click off for basically the entire 3 day cold crash I like to do. The fridge will eventually give out at which point I’ll get a legit glycol system... probably an icemaster 100. Good luck! Recommendation:
“The Container Store” is a great place to find the perfect reservoir. If you have one of those in your area that’s is. The size of the reservoir has a kind of diminishing return as well. Too small and it’ll heat up to quick. Too big and it won’t re-chill fast enough for your application.
Other recommendation:
Depending on how handy you are I would suggest building a 5000BTU air conditioner glycol system. Friend of mine built one and uses it to chill a 1bbl unitank. It works unbelievably well. I guess if you’re only EVER planning on chilling that 7 gallon tank you’ll be fine with the mini fridge build, but the 5000BTU build is futureproofing yourself when and if you expand/upgrade.
GOOD LUCK!

 

[Beerwildered]

Very helpful. Thank you!

 

[mcsquared]

Hey all. Sorry to bump an old post. New to the forum and newish to brewing. Looking to get a bit more serious and start temp controlling during fermentation.

I’ve got a mini fridge and have started planning out this build. My question is, would it hurt anything to submerge the fridges stock temperature probe that’s connected to the freezer compartment? Or would it be better to disconnect it and leave it outside of the glycol mixture?

Thanks for this idea! Much cheaper and simpler than other options.

 

[Metzen]

I would leave the temp probe out of solution so the probe stays warmer and keeps the freezer chilling. You can then rely on your controller to turn the fridge on or off to manage the glycol temp. Cheers.

Hey all. Sorry to bump an old post. New to the forum and newish to brewing. Looking to get a bit more serious and start temp controlling during fermentation.

I’ve got a mini fridge and have started planning out this build. My question is, would it hurt anything to submerge the fridges stock temperature probe that’s connected to the freezer compartment? Or would it be better to disconnect it and leave it outside of the glycol mixture?

Thanks for this idea! Much cheaper and simpler than other options.

 

[sensei247]

Thanks for all of this- building one of these this weekend.

Quick question- is there any issue with evaporator coil input/output location on the fridge itself? I have a fridge where the evaporator coil connects to the rear of the fridge. I see @Metzen 's connected to the right side.

Also, is there any place in these connections (e.g. metal evaporator coil attached to rubber hose that can move). I attached an image of my fridge evaporator coil. Appears that @Metzen s evaporator coil line in enters the evaporator coil into the "side" of the coil whereas this image shows mine entering the base of the coil...not sure if this is going to matter when I go to bend it.

 

[day_trippr]

If you can only identify a single tubing connection to the cold plate, that line is actually coaxial - there's a capillary input tube inside the outer return tube.
So, obviously, one has to be wicked careful bending that tubing...

Cheers!

 

[sensei247]

Ah! Thanks for that. Also looks like from
Other diy chillers that the tube which feeds into the wall has some excess to it so if I can detach and pull away from the wall (gently) this might work. Thoughts?

 

[day_trippr]

It's all very scary no matter how it's sliced. I have seen it done successfully here on HBT, and have read of fails as well (not many though), so extreme care is the only recommendation I have...

Cheers!