Turning my brew fridge into a glycol chiller

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Simonh82

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I am considering updating my fermentation equipment and I would really like to get a 60L Fermzilla All-Rounder. I mainly brew hoppy pale ales so I would like to be able to do closed transfers to keg. I am not particularly interested in pressure fermenting for the beer styles I mostly brew but it would be nice to be able to carbonate during fermentation to save some increasingly expensive CO2. I currently use this 35L flat-bottomed SS fermentor which is great for the price but doesn't allow for easy closed transfers and has a very large opening which means I need to carefully purge with lots of CO2 to minimise oxidation when dry hopping.

The 60L Fermzilla won't fit in my under-counter brew fridge and I don't have space for a larger fridge, so I am thinking about how I can maintain a constant temperature during fermentation with the 60L Fermzilla. My thought is that I would have the Fermzilla out on the countertop with the addition of a cooling coil and thermowell added to the Fermzilla. I would then add a large tub or possibly use my existing fermentor to hold a large reservoir of water with a bit of glycol in. I would add a submersible pump to the water and control this with an inkbird controller. The water would be kept at 1°C by the fridge and circulated through the fermenting beer when the temp got to high. I already have one hole drilled in the side of the fridge from an aborted attempt to be able to run a gas line in in the past, so I think it should be straightforward to run another one to allow the water to circulate through 3/8 beer line. I know that glycol isn't strictly necessary for this temperature but I have sometimes had ice forming on the back of the fridge and I want to avoid the chance of things freezing and breaking the pump. I am aware that this would probably struggle to cold crash down to really low temps but as I mostly make hazy beers, dropping down to 5-6°C would be fine. I would probably get the Fermzilla insulating jacket to help maintain temperature.

Does this sound like a plausible solution?
 
The efficiency of these solutions are very low, try to get yourself a maxi or similar chiller, and you're good to go.
 
The efficiency of these solutions are very low, try to get yourself a maxi or similar chiller, and you're good to go.
A new glycol chiller is way outside my budget. It looks like Maxi chillers are about £400+ so I would much prefer to use the existing equipment I have.

When you say the efficiency of these solutions is very low, do you mean their ability to cool the fermenting beer or the efficiency of running the fridge to keep the water/glycol cool? I would have thought that having a large reservoir of liquid would keep the temperature pretty stable when you are just trying to keep the fermentation temperature in check. I can see that if you were trying to drop the beer temp by 15°C for a cold crash it would probably take quite a while but I am not overly concerned about that.
 
A new glycol chiller is way outside my budget. It looks like Maxi chillers are about £400+ so I would much prefer to use the existing equipment I have.

When you say the efficiency of these solutions is very low, do you mean their ability to cool the fermenting beer or the efficiency of running the fridge to keep the water/glycol cool? I would have thought that having a large reservoir of liquid would keep the temperature pretty stable when you are just trying to keep the fermentation temperature in check. I can see that if you were trying to drop the beer temp by 15°C for a cold crash it would probably take quite a while but I am not overly concerned about that.
You can have a look on 2nd hand maxi chillers, if I knew about them when I bought my GF chiller, id saved a lot of money.

Under efficiency, I meant the energy you put into the system compared the cooling you get out. If you wanna look at it from an another perspective, it'll be very expensive on a long run.

In my experience with the GF the solution has to be at -5 c° to able to cold crash 2 fermenters simultaneously.
 
If your aim is simply to control fermentation temperatures with yeasts which like to ferment in the 17-20C range then you'd probably get away with a solution such as the one you suggest, but you'd struggle to get lager temperatures and cold crashing would be out of the question in my opinion, even with an insulating jacket on the fermenter. A fridge is designed to maintain the temperature of a well insulated space using the lowest possible amount of power (usually around 50w); it just won't keep up with a heat load such as an external fermenter because a 10mm neoprene jacket on a fermenter is a pretty poor insulator compared with the 40-50mm of expanded polystyrene which surrounds the fridge compartment.

As others have said, a beer line chiller (i.e. Maxi cooler) is definitely the best solution. They are around the £100 mark on well known auction sites (although there are some hopelessly optimistic people on there who believe they're worth £200-£300 just because they ran a damp cloth and vacuum cleaner over the front). Worst case, you can sell it again for what you paid.
 
My friend ran his system like that for a while. If you turn the fridge temp tail upto max then it continually runs so you can get temps down to 1C. I've turned beer to ice in my home made kagarator fridge before when I've left the dial on max...though not all fridges are the same I agree. The bucket of glycol was in the fridge with a submersible pump - the grain farther kit controlled by his grainfather, and it worked fine. Not sure how many fermenters you can run from it but for one single grainfather it worked just fine. Could run with a small chest freezer instead of a fridge then maybe you'd have sufficient capacity to run several Grandfathers or one larger fermenter.

Just took up alot of space compared to the Maxi setup. I got my Maxi used for £250...but they are going up in value on eBay I've noticed and you'll struggle to get one for less than £350 now and a that price it would be pretty beat up...mines like new. Also look for other brands...they're all essentially the same thing but there are other brands other than Maxi and they might fetch a lower price....my mates is a Calypso and it is identical to my Maxi but is just painted green instead of black.
 
I’ve just picked up 2 maxi 310 for £100 from fb marketplace. The bloke runs an events company and is replacing all there coolers - he had a lot of other coolers to shift and was after £50 a piece… if anyone wants details I can pass them on, he’s based CV47
 
I seem to be trying the same thing... Any thoughts / lessons please?
Haven't done it yet so let me know how it goes if you do. I still think that with a large enough reservoir in the fridge it could be fairly efficient but my grasp of thermo dynamics is rudimentary so I could be wrong.
 
My experience is that some fridges ( might be all) if you turn the thermostat to max then this is actually on all the time and is a setting that is intended to be used for short periods if you're turning the fridge on for the first time or filling it with warm produce. I've had a fridge on this setting for a period of time and froze a keg of beer, so fridges can indeed get cold enough to freeze water. Also my current brew fridge has a 1 degree C setting so depends on the fridge.

The maxi's work well, thats what use. I rigged my product coils in series so the cooling fluid gets two passes through the ice bath...I also used glycol as having the cooling fluid sat in the product coils inside an ice bath was surely going to freeze it. It does struggle to get much below 3 degs C for cold crash, especially when its hot during summer, but 3 degrees C seems to be perfectly sufficient for a decent cold crash.

However if I were to run more than one fermenter from it I'd probably do the mod where you remove the product coils, fill the bath with glycol and bypass the in-built thermostat with an Inkbird ST1000 so you can chill the glycol bath down to -5 degrees or more and recirculate directly from the glycol bath. I think if you were trying to cold crash one batch at the same time you're maintaining ale fermentation temps in a second ferment then it might struggle.
 
I can confirm that a fridge pump works for maintaining temps.

I use a refrigeratated reservoir which is pumped through a coil in the fermenter, inkbird controlled.

No glycol required.
 
I bought my used ice maker for 35€, there are plenty of those in second hand markets for very cheap prices. For what is worth, with that setup I can cold crash a 27L Fermzilla with insulated jacket with an ambient temperature of 24C.
 

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