Best practices for glycol chiller setups

Hardware fridge-build
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Hi community.

I would like to share best practices and learnings with glycol chiller setups and brewblox.

Let me start with my setup and learnings so far. I build myself a fermentation setup consisting of a brewpi/brewblox, a canonical (ss-brewtech unitank, 14gal), and a modified accompanying cooler as a glycol chiller. I removed all heat exchange coils from the accompanying cooler and use it now as an active cooled reservoir for a 45l water to 10l propylene glycol mix (~20%). I submerged a 12v pump into the reservoir which is activated to circulate the cooling liquid through the canonical’s chiller coil.

To measure temperature, I submerged one one-wire temperature sensor into the glycol chiller and placed another one into the canonicals thermowell. A 230 V AC SSR switches the glycol chiller’s compressor and a 12V DC SSR switches the circulation pump. A one-wire ssr expansion board connects both SSR connected to my Brewpi Spark 3. Of course I could switch those SSRs directly with my controller, but I need his outputs for the SSRs of my HERMS setup. I really like the fact, that I can use the controller for mashing and fermentation at the same time!

I created the brewblox control setup with the glycol chiller wizard. A really easy process.

My settings/learnings so far:
The glycol chiller is set to a fixed temperature (for lager fermentation I choose 4°C). The fermentation process runs pretty well and brewblox controls the temperature within a precise range (below 0,5°C deviation).

I have some trouble with the cold crush though. I tested some settings, but I never reach a beer temp of 0°C. My first try was with -5°C for the glycol mix. No freezing in the chiller, but maybe it’s too cold and freezing beer builds an isolation around the coil. Raising the glycol temperature to a higher level (-2°C and 0°C) did raise the temperature again above 2°C. I had no chance to look into the tank since it’s under pressure.

This leads to my first question:
What are the best practices with this setups for cold crash?

Also I’m asking myself, if it would be a good idea to drive the chillers temperature by the setpoint temperature for the fermenting beer. For example the temperature of the cooling fluid could be always 6°C below the setpoint. For more than one connected tank the lowest setpoint shoiuld be chosen. This saves energy and might prevent freezing if you ramp down to cold crash really quick. Doers anybody have thoughts or experiences regarding this?

I’ld love to share my insights and discuss optimizations with people with such setups or people planning similar ones. Does somebody want to share additional learnings with those setups so far?

4 Likes
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I don’t even have glycol in mine now, just water. When cold crashing, I set it to 0.5 degrees.

Using a too low temperature tends to create ice around the coil, which creates an insulation layer.
SS brewtech recommends 28-32F (-2.2 to 0C): https://ssbrewtech.zendesk.com/hc/en-us/articles/203532699-Optimal-temp-for-glycol-water-solution-should-be-what-

You could experiment with an offset actuator to use a dynamic setpoint for the chiller. I have not done this myself, because chiller (Lindr AS-80) also cools my taps.

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Hi @Elco, thanks for your answer.

I’ll try which glycol chiller temperature is working best for a cold crash. I added the glycol, because I had already an ice block in my chiller when the circulation pump did not run for a while during the diacetyl rest (i also removed the stirrer). But glycol lowers the heat transfer capacity as far as I know. This is probably the reason why I need a lower temperature.

In my cellar I have the following results so far:
-1°C chiller => ~2,7°C beer
-2°C chiller => ~2,5°C beer
-5°C chiller => ~0,7 - 1°C beer

So I’m not sure about the sweet spot. SS brewtech’s recommendation seems not to work for me.
@Elco: What is your ususal cold crash temperature? What’s your environment (cellar, garage,…)?

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It’s a garage. I cold crash at 2C, with the glycol/cooling water just above freezing. It is hard to get lower, because the neoprene insulation jacket of the SS Brewtech conical isn’t very good. I even put an extra layer of insulation material between the jacket and the conical.