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Smart scene with schedules for central air-conditioner

A standard US single family house has a central air-conditioner system - HVAC. Almost certainly, you don't want to put the temperature sensors where the HVAC is, or where the control panel is. You want sensors to be in the bedrooms, bathrooms and where you work and play. 


To control the HVAC, the only sensible way is to use smart scene. You put the sensors where you want them to be, and put Sonoff switch(es) at the HVAC or control panel. First, it's expensive for now to use Sonoff TH just to send the sensor information to eWeLink.


More importantly, HVAC control needs schedules. For example, the temperature setting should be lower when people are sleeping and they are off to work on weekdays. For now, you can control each Sonoff switch by a timer or by a sensor, but not both. All HVAC controllers have schedules call "programs". If the smart scene can do this, you have virtually unlimited number of programs. Smart Wifi HVAC controllers with App control cost hundreds of dollars for now.


I am serious and now I have TWO Sonoff for each "program".  I use the SV version as they have 5V direct output for control of additional 5V relays for the 24 VAC control voltage of all US systems. One Sonoff is the timer enable switch on schedules. The other is controlled by sensors. If I have daytime and nighttime schedules, I need 4 Sonoff. If I add an off-to-work daily schedule I need 6. This is not bad at all compared to the cost other smart thermostat controllers. And since the HVAC has it's own room, I can put all the smart junks inside with nobody noticing. It's also very easy to maintain.


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