DIY Glycol Chiller Build

[ethan44]

Hi All,

I've been fermenting in a temperature controlled fridge for about 6 years now. I've recently upgraded my brewery into a 40L (10G) 3 vessel HERMs. I often end up splitting the batch into 2 x 20L using different yeasts etc. Although I can fit 2 plastic fermenters in the fridge, I cannot run them at different temperatures. I figured I'd up my fermentation game.I don't really have room for 2 fridges in the garage, can't pass a $1000 glycol chiller pass the wife and I like building stuff, so a DIY glycol chiller it is. In the future I'll be looking to purchase 2 new fermenters (at this stage, the Fermzilla) that can take a heat exchanger coil.

Kept an eye out on facebook market place and managed to pick up a portable air conditioner unit for $50NZD. Window AC units are very rare in New Zealand, so I couldn't go that route. At this stage, I've managed to hack it all apart into just the items I need from the AC unit.

A few people warned away from a digital AC unit in their builds, but I didn't find it to be an issue. It was just a matter of tracing the wires that ran to the compressor and bypassing the control unit. I kept in the starter capacitor. I'll be controlling it all off an STC-1000 unit.

Still a lot of things left to do. I need to track down a cheap and appropriate sized chilly bin (cooler) and some pumps. I would like one smaller pump for glycol recirculation in the cooler to prevent stratification, and one for each fermenter.

I'll need to work out a way to mount the cooler and fit the heat exchanger into the cooler. As this was a vertical AC unit, the two HEXs are stacked on top of each other. I may keep it that way if I can't work out a way to bring the HEX down to ground level.

Here is a link to the build so far.

 

[Harleybrew32]

good luck on it.

 

[ethan44]

Managed to very carefully bend the HEX down lower. I did try to have the cooler up top, but I'd rather the whole thing be lower and have a bigger footprint.

 

[Gruel]

Looks good. The small 12V aquarium pumps I list in my peltier chiller thread are holding up ok so far for several months now, but they are from the (north) american amazon, so maybe not available in your neck of the woods. Pumps of that type might actually be large enough for your needs, since you don't really need to circulate that much cold liquid as long as your fermenting (or storage) vessels are reasonably insulated, and you have good thermal contact between your cooling coils and the vessel (and the liquid in the vessel).

Apropos insulation: condensation can really get you, so that is something to watch out for. The huge latent heat of water can overpower even an oversized cooling unit like yours. If you keep your cooler open, you might even overflow it due to water condensing into it, depending on how humid it is.

I also found that my NTC thermal probes, even though nominally waterproof, do not like being in liquid for any length of time. So that might be another thing to watch out for; use a thermal well (for the cold side reservoir/cooler), or attach the probes to the dry side of things (fermenters/kegs).

 

[TheMadKing]

I just learned that kiwis call coolers chilly bins and I don’t think I can go back to saying coolers...

 

[ethan44]

Looks good. The small 12V aquarium pumps I list in my peltier chiller thread are holding up ok so far for several months now, but they are from the (north) american amazon, so maybe not available in your neck of the woods. Pumps of that type might actually be large enough for your needs, since you don't really need to circulate that much cold liquid as long as your fermenting (or storage) vessels are reasonably insulated, and you have good thermal contact between your cooling coils and the vessel (and the liquid in the vessel).

Apropos insulation: condensation can really get you, so that is something to watch out for. The huge latent heat of water can overpower even an oversized cooling unit like yours. If you keep your cooler open, you might even overflow it due to water condensing into it, depending on how humid it is.

I also found that my NTC thermal probes, even though nominally waterproof, do not like being in liquid for any length of time. So that might be another thing to watch out for; use a thermal well (for the cold side reservoir/cooler), or attach the probes to the dry side of things (fermenters/kegs).

Awesome, thanks for the tips. I was looking at aquarium pumps on Aliexpress. I use 25W magnetic pumps in my brewery that are plenty strong enough, so I think I will be able to find some lower powered ones that will do the job.

The fermenters (fermzilla) I am looking at do have an insulation jacket, just not sure how snug fitting it'll be. I could always make a custom neoprene jacket. I'll see what I can do in terms of sealing the chilly bin. I guess through wall (or lid) fittings would be the best here, same with the probe by the sounds of it.

I just learned that kiwis call coolers chilly bins and I don’t think I can go back to saying coolers...

Good, spread the Kiwiness! We have some quite strange colloquialisms here.

 

[Tallgrass]

I would use a larger chilly bin and get all the connections through the side. That way you can close the lid to prevent evaporation. I clean mine out ever few months (just water ,no glycol) and it loses very little volume. Probably just loss from drips when moving the output from fermenter to boil kettle chiller.

I started out planning for glycol. I used water to test everything and works just fine to chill the boil kettle and cold crash a fermenter to 40f. Set at 34f with a pump to circulate water while the compressor is running to prevent any ice.

 

[ethan44]

I would use a larger chilly bin and get all the connections through the side. That way you can close the lid to prevent evaporation. I clean mine out ever few months (just water ,no glycol) and it loses very little volume. Probably just loss from drips when moving the output from fermenter to boil kettle chiller.

I started out planning for glycol. I used water to test everything and works just fine to chill the boil kettle and cold crash a fermenter to 40f. Set at 34f with a pump to circulate water while the compressor is running to prevent any ice.

Thanks for the advice. Just running water would save a bit of cash, rather than buying a couple of gallons of glycol.

 

[TennBrewer]

I built one a while ago and found that I needed a bigger cooler (chill bin) than the 40 qt I was using. Also, with a glycol/water mix you can chill below freezing. If I had it to do over again, I would use an 80 qt bin with 2.5-3.0 gallons of glyclol and 6 gallons of water. Be aware that some parts on the heat exchanger are not stainless steel and will rust after awhile.

 

[ethan44]

I built one a while ago and found that I needed a bigger cooler (chill bin) than the 40 qt I was using. Also, with a glycol/water mix you can chill below freezing. If I had it to do over again, I would use an 80 qt bin with 2.5-3.0 gallons of glyclol and 6 gallons of water. Be aware that some parts on the heat exchanger are not stainless steel and will rust after awhile.

Awesome. I think I'll try find the biggest cooler I can find. Annoying about the rust, but I guess there isn't too much you can do about that.

 

[ClaudiusB]

Awesome. I think I'll try find the biggest cooler I can find. Annoying about the rust, but I guess there isn't too much you can do about that.

Glycol Corrosion Inhibitor (Food Grade)