Freezer over fridge glycol chiller build

[CRAFTBEERKING]

A couple years ago I was fortunate enough to acquire a used fridge from a buddy which I rapidly converted to my first keggerator. I have an SS Brewtech 7 gallon chronical fermenter with the FTSS temp control on the way. What I am looking to do is run the coolant in and out lines into the freezer compartment on the same fridge unit. Inside would be a 7 -10 gallon reservoir with glycol solution. I also have an old immersion chiller from a DIY build years back. I'm hoping that if I run the line coming into the freezer through the coil (coil is also in freezer box) then back into coolant reservoir, that the coolant temp will remain low enough for the system to be reasonably efficient.

I have read up on some of the posts detailing the BTU output of freezers being significantly lower than that of the AC builds. However. I am trying to use what I have first, before going out and buying more stuff to rip apart.

I also have a basic understanding of heat transfer-ie the air in the freezer has insulating properties; direct contact with coolant coils is more efficient.

I understand the inherent danger in drilling through a freezer wall, but I am handy enough to manage that without any trouble.

My questions for the more savvy DIYers are:

Assuming the reservoir has a seven gallon capacity, Is the cooling capacity of this freezer adequate to keep my ferm vessel at temp? (I only ever do 5 gallon or less batches)

Would I even need the immersion coil in the freezer or could I just run the line back into the reservoir?

Any help would be greatly appreciated!

Drinking: Oak aged Yeti
Bottled: Babygirl Chocolate Coffee Stout
On tap: Tubaweizen
On Deck: All grain harvest brew of some sort

 

[DeBrewer]

So you will have a fermenter sitting adjacent to the refrigerator and then run coolant lines into it correct? I just went through a similar exercise in research. Basically you can trade out BTU capacity for liquid capacity. You could start with a reservoir in the freezer and do some temp test. If it cannot keep up, then look into a "pre chiller" coil/reservoir in the refrigerator. In that scenario it is best to have 2 reservoirs. One reservoir for you "cold" glycol in the freezer and a secondary reservoir in the refrigerator that collects the warm glycol and pumps back up once it has been cooled to a certain degree. That way your "warm" glycol does not warm up the cold glycol that is needed to chill the vessel.

On a side note, for my keezer and glycol chiller, I used a foam weather stripping to space out the lids on my freezers and then cut slits in the gasket to run lines through. Most of the hinges have enough play that I didn't have to modify the freezer at all. This way I do not have to cut any holes but I get the same functionality of a small collar.


Good Luck!

 

[CRAFTBEERKING]

Yup, that's the idea-have the ferm right next to the fridge. The FTSS I spoke of has a pump and temp control mounted to the lid. Naturally the in and out lines would run from that to the reservoir in the freezer.

Update: I found a perfectly sized 10 gallon tub for the reservoir.

Great idea with going through the gaskets! It looks like, per your suggestion, I'll do some testing with the reservoir. Hopefully the pre-chiller won't be necessary. I think I'll move forward with the build.

Do u think the addition of my copper chiller coil I mentioned in the original post in the freezer would have any effect? It's about 50 feet of 3/8ths ID.

Thanks for your help!

Primary: Empty
Secondary: Empty
On Tap: Tubaweizen
Bottled: Babygirl Chocolate Coffee Stout

 

[DeBrewer]

It wouldn't hurt if you had the room but I would imagine that a larger volume would be more beneficial. If you have the room for a coil, submerge it in a container filled with water. Basically let it freeze into a solid block. I have never done it but read about it somewhere. It will help keep the coil chilled instead of relying on ambient temp in the freezer.

Good luck and report back with info and pics!

 

[CRAFTBEERKING]

Sweet, I'll def freeze the coil in a block then.

I have most of the hardware and parts. When the ferm arrives I'll start posting picks of the build.

Cheers!

 

[Semco]

Curious how it turned out I’m planning the same thing shortly.

 

[Gruel]

Thermal conductivity of ice is about 2 W/(m*K), which is better than water (0.6 W / m K), and definitely better than most plastics (0.2 W/ m K), but not great. Copper is close to 400 W/m K, aluminum depending on the alloy 100 to 200 W/m K. So you are definitely better off with direct metal to metal contact between your piping and the evaporator of the freezer. Can you have the coolant (water/glycol mix) in direct contact with the evaporator? That would be best.