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Frozen flow :)

This category is creaBest,

At the moment I have my pond pump that is switched to daylight. Now I would like not to have the pond pump switch on if it is freezing or has frozen in the night.

Do you have any advice because I can’t figure it out with the KNMI app. And I want to do it without sensors.

thankyou for the help.ted to show, and explain the working of specific Flows in homey.

It will not be easy to realize this without any problems.

The easiest way to protect the pump not being switched on if it’s to cold (at the moment when the flow is triggered), is to use the Homey internal weather data. Because these values do not 100% represent the actual temperature, a certain tollerance should be taken into account.

Add a logic card in the And… section.

And…

– Temperature ist greater than 3 °C
(Logic → (tag) is greater than → tag → Weather “Temperatur (°C)”)

This additional logic card doesn’t protect the pump against being switched on when the pond is already frozen and the air temperature rises above 3 °C again !!!

To prevent the pump from being switched on when it has frozen during the night, additional flows and a numeric variable are needed.

Flow 1
If…
– Every 15 minutes
And…
– Temp. (Homey Weather) is less than 3 °C (or 2 or 1 °C, you have to try it out!)
Then…
– Set variable “LowestTemperature” to temperature (Homey Weather)

Flow 2 (needed to reset the stored temperature in the numeric variable)
If…
– The time is 14:00 o’clock
Then…
– Set variable “LowestTemperature” to 10 (e.g.)

Now you can add the numeric variable “LowestTemperature” also to your main flow in the And… section.

And…

– Temperature ist greater than 3 °C
(Logic → (tag) is greater than → tag → Weather “Temperatur (°C)”)
– Variable “LowestTemperature” is greater than 3 °C

Because the temperature values are only values from a weather service and do not represent the actual temperature at your home, it cannot be guaranteed if the pond is frozen or not. Furthermore, there is an additional risk that if the temperature has been above 3 °C for several days and nights, the pond may still be frozen.
For additional safety you could add a virtual switch that you manually turn on (in case of ice) or off and add it to the flow. Or you can use the virtual switch to turn the main flow on or off.

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