Questions/help with Simple Rule

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1

Hey all. I am trying to control a dorm refrigerator to be used for brewing yeast (for beer). I need to maintain the temperature between 48F and 54F. I can't use the internal thermostat because at the lowest setting it's still goes down to the upper 30's. So I'm trying to do this with a Z-wave temperature sensor and a switch.

So the rule is supposed to work with the trigger being the temp is above 54F and if it is, it turns of the fridge. Next, there's a 10 minute delay because I've read you shouldn't cycle a compressor too often. Then, it waits for the temp to drop below 48F then turns off the fridge.

fridge
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The temp sensor ( Zooz ZSE44) seems to report temperature updates when it wants too. Maybe I need to tweak the advanced parameters to get better control. Anyway, what happens if another temp trigger comes in and triggers the rule again? Do I have 2 instances of the rule running simultaneously? Also, is "Wait for Expression" the right thing to do here? I didn't see anything like "wait for temperature".

2

If the temperature report > 54 again it will re-trigger the rule. Yes, you will get another instance of the rule but Waits are automatically canceled on a trigger so you'll get a stack up of Delays only. Probably not a big deal. You can change the Delay to Wait for event: elapsed time 0:10:00 and eliminate that issue. Wait for Expression is fine as is Wait for Events. Expressions are states where Events are changes in state.

You can limit the rule to only triggering once by setting up a Required Expression for temperature <= 54. It'll only trigger when the temperature crosses 54 as it's increasing.

3

Thanks for clarifying that!

4

My uncle is a long time home brewer and he uses a chest freezer for this where he changed out the thermostat. You might consider that instead of an HA solution as the fridge will likely last longer.

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