Use Brewpi like a coolbot

I was wondering if I could use my brewpi like a coolbot on an AC window unit in the fermentation chamber.
Any thoughts suggestion? ELCO?

If you can make an SSR turn the air conditioner on and off, I see no reason why not.

Well I guess the real question is. The window unit can only be set as low as 60F what if i want to go lower?

What the Coolbot does is turn on the a/c unit full blast, allowing the temp to drop below 60. To prevent ‘freeze up’ of the fins it seems to have a sensor on the fins. BrewPi can, as Elco mentions below, be used to override the in-built thermostat. However, don’t think the Brew-Pi software addresses the ‘freezing’ issue.

Well, then my next question would be how would I override it? Not sure how I would do that. I’m sure it is different for specific AC unit. I wouldn’t need it to go that low, maybe like 45 50.

What you are going to be doing is overriding the internal thermostat, replacing it with one of the BrewPi temperature sensors. Ideally, if you have the capability you would remove the internal thermostat or bypass it and let the SSR controlled by the BrewPi switch the a/c unit on and off. If I remember correctly, on the CoolBot site there are descriptions of how to bypass the internal thermostat, including the secondary thermostat that some large a/c units have. If you are up to it, you can build a BrewPi controller for about one thris to half of what the CoolBot costs. However, as mentioned above, remember that BrewPi does not have a way to sense and allow for the freezing issue. That could be a problem.

If you have a friendly a/c mechanic, you might ask him

I did some research of my own on this. What I found was,

  1. If you can find a way to move the sensor outside the chamber. This would keep it running because it wouldn’t be able to reach its set temp.
  2. On digital AC units, a simple on/off SSR to power will not work because it may require the user to push a button to make it start again. The way around may be too but the SSR between the compressor and not the power, so that it stays on always.
  3. Freezing issue you might not be able to cold crash but other than that it should be fine.

The freezing issue to which I referred was a sensor that the CoolBot has that is inserted in the fins of the a/c unit. I am guessing that if the temp gets too low on the fins, the CoolBot temporarily stops the a/c to let it warm up a little.

Yes I agree, my thinking is that my chamber is small and won’t need to run as long. They are using it for giant walk-in cooler.

Obviously, BrewPi is a more cost effective solution than CoolBot. I would build your cooler and just keep an eye on the a/c elements (fins). If you see ice build up, you might need to have an extra sensor and then have Elco instruct you how you could tweak the settings to react to the a/c freezing.

Good luck

To prevent the freezing all you do is put an additional temperature probe inside the machine. If the temp reaches anywhere near 2’C you stop the machine for a little bit, until it reaches at least 6’C internal.