Metzen's Mini Fridge Glycol Chiller Conversion

[tjpfeister]

In case anyone is following- the first two hours of run time demonstrated a problem. The condenser simply wasnt built to dissipate THAT much thermal energy. The fridge smelled hot and the compressor kept tripping the thermal breaker. After 2 hours it had stalled at 54F when starting at 62F. Air movement is needed.

Tonight I purchased a small fan and positioned it to blow over the condenser and compressor... The results are much better, the first hour dropped 62F down to 47F and the unit is not getting hot. By my math 15Fx10galx8lbs= 1200btu

Thats not massive, but it is a respectable number. Ill keep it running and post back the results as I feel significance warrants.

Suffice it to say, without a condenser fan this project will not work.

 

[Ruint]

That is valuable information that you shared tj...thanks for your continued updates and look forward to your findings!

 

[Bkenyon61]

Metzen,
Have you added a 2nd fermenter? If so, I assume you you ran a separate set of lines. Is the 3 gal of glycol water mix sufficient or did you increase the size of the reservoir? Did immersing more of the coil help. I am using 7 gal chronicals and want the ability to control 2 different brews. I am trying to decide to go the ac route or yours. This is cleaner look.

 

[tjpfeister]

Sorry to butt-in, but I can add some insight. I used Metzon's notion and set up the fridge as a 10gal tank, with two circuits (planning on adding a second vessel, likely 7gal). The 10 gal bath, set to 20*F, is capable of getting my uninsulated fermenter down to 42*F. This does tend to tax the glycol fridge, and it runs continuously even with a fan blowing on thr condenser. (You need to add a condensor fan if you plan on chilling a larger volume of glycol, there's too much thermal mass for the light duty condenser to dissipate). With this in mind, temp controlling several vessels is not an issue, but cold crashing may be, depending on ambient conditions. Hopefully insulation remedies this, but my personal rig has only be used to test water and is currently working on its first batch of beer.

I would love to hear more back on what the OP has found with his; cheers!

 

[Bkenyon61]

I got the SS Brewtech FTSs2 conversion kits and it includes the insulating jacket so it should be more efficient. With my set up I would typically have 5.5 gal in the fermenter and I could see these Being at diffferent temps. Based on other posts a 5000 btu ac unit with 6 gal glycol mix is more than sufficient. Do you think a mini fridge would achieve the same return

 

[narddawg314]

Sorry to butt-in, but I can add some insight. I used Metzon's notion and set up the fridge as a 10gal tank, with two circuits (planning on adding a second vessel, likely 7gal). The 10 gal bath, set to 20*F, is capable of getting my uninsulated fermenter down to 42*F. This does tend to tax the glycol fridge, and it runs continuously even with a fan blowing on thr condenser. (You need to add a condensor fan if you plan on chilling a larger volume of glycol, there's too much thermal mass for the light duty condenser to dissipate). With this in mind, temp controlling several vessels is not an issue, but cold crashing may be, depending on ambient conditions. Hopefully insulation remedies this, but my personal rig has only be used to test water and is currently working on its first batch of beer.

I would love to hear more back on what the OP has found with his; cheers!

Do you have any in progress photos of how you sealed that fridge? Or what materials you used?

 

[tjpfeister]

Do you have any in progress photos of how you sealed that fridge? Or what materials you used?

I intend, at some point, to start a thread with all the details. Short version on the story is to use 1/4" thick polycarbonate (not plexiglass), seal it all with silicone (I recommend Permatex The Right Stuff- found online or at automotive stores), and I built the steel frame with 1/8" x 1" stock cut and welded to fit. Screw holes were all countersunk so the surface is flat and the door seal sits flush.

 

[jaymosbeershack]

Looks really nice. Way cleaner than my set up. I dealt with my cold crash by adding a condenser/evaporator with an extra copper coil in a block of ice. Keeps the glycol cold for the long running.

 

[tjpfeister]

Not pretty, but I insulated the lines and fridge. You get (predictably) diminishing returns as delta-temp between glycol and beer gets smaller, but by stepping the temp down in increments, it allows the glycol bath to recover and successfully hammer the temp down each time. Pardon the clutter, but here it is at 38*F. I could likely push to 35 if I wanted to listen to the pump run more.
So at this point I have to call mini-fridge-large-glycol-volume-chiller a success.

 

[tjpfeister]

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.

 

[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.