I just received my first Shellys and was hoping to use the Shelly 1 with temperature add-on to control beer fermentation temperature using a cooler.
What I want is to change the target temperature occasionally (at most one or two times a day). That is easy to do with the Shelly by using a http call to change the temperature thresholds but the problem is that I also want a delay of D seconds before turning the compressor on to start the cooling cycle.
I have looked at discussions in this forum like output delayed but they depend on a http call to trigger the device each time. I don't want to do that because the cooling/not-cooling cycle needs to be independent of any external services or the workings of the Wi-Fi. If there is a temporary failure in turning the cooling on/off it could ruin the batch of beer. So I want the setup to be as self reliant as possible.
Since the Shelly doesn't have a configurable delay before turning on/off, I have come up with a solution that requires two additional Shellys shown in the picture. There are two parameters: T as the target temperature +/- 0.5 and D as the turn-on delay.
Brew - Shelly Refrigerator temperature controller with turn on delay_autoscaled.jpg
It works like this:
When temperature is below the threshold, A goes off so C is off regardless of B.
When temperature is above the threshold, A goes on which turns B off because the switch settings of the Delay are reversed. After the delay time has passed, it turns B on which feeds into the Relay and turns the compressor on. This state will persist until the temperature drops below the threshold again.
I have tested this with a DS18B20 probe using a light bulb as the load and it seems to work fine. Next step is to put it in action for the fermentation fridge.
I would be happy if someone could show me how to do this using fewer Shellys or tell me if there is a problem with this setup.
Hint to the developers: If the Shelly would support a delay before turning on or off (which looks like a simple feature), that would be perfect and would make the Shelly a very cost effect alternative to products like Inkbird for temperature control.
