Cycling HVAC fan when CO2 levels cross a defined threshold

#1

I have 2 Netatmo weather stations and 2 Ecobee3 thermostats. I’d like the Ecobee’s to change the fan mode from “Auto” to “On” if either CO2 level crosses the defined 650 threshold, and receive the notification “CO2 Levels High.” I’d then like the piston to check every 5 minutes for example, and when the CO2 Levels drop below 650, change the fan mode back to “Auto,” and push the “CO2 Levels Normal” notification. The piston as configured will accomplish the first part above, but if the levels are below the threshold, every 5 minutes I get the “CO2 Levels Normal” push notification (when un-paused of course).

“Thermostat 1” and “Thermostat 2” are the sanitized names for Netatmo. 3 and 4 are the Ecobee’s.

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#2

Try using a local variable:

Define
Boolean co2high

IF
Mode is x y or z
AND
co2 is greater than x
THEN

IF co2high = false
turn on fan
send notification
set variable co2high = true
end if

ELSE

IF co2high = true
turn off fan
Send notification
set variable co2high = true
end if

end if

This will toggle between true / false once per cycle rather than triggering every time the co2 level changes.

#3

Thanks for the help - I’m definitely making progress. What constitutes a cycle in this example?

#4

Co2 goes above value, triggers one message, fan on, co2 goes below value, triggers one message