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Switching 24v Thermostat Power with Sonoff SV

Hi all, I'm trying to hookup a sonoff to switch power on/off to a set of thermostats in my radiant floor heating system.  The power supply is a 24v supply thus my trying to do this with a Sonoff SV.  The power supply is here:

http://www.packardonline.com/Shop/PrintProduct/5735


I've attached a picture of how I wired this up, positive (red) to in+.  When I plugged it in the resistors below the input blew/popped.


Did I wire it incorrectly or should I be using a Sonoff Basic?

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Hopefully you have solved your issue by now, but I will chime in on this in case anyone else is searching for it.


The 24Volt on your existing system will be 24Volts AC most likely.  Most 24Volt thermostat systems are AC.  The Sonoff SV needs a DC voltage and 24Volts is the maximum it can use.   

As the relay is directly switching the power supply, it is not possible to use a Sonoff SV on a 24Volt AC system.

Even if you used a rectifier, it would not be suitable for two reasons.  One, your existing system wants AC and two, the Rectified DC would be well over the 24Volt maximum the SV can handle.


You need a dry contact or voltage free relay to do the job you want to do, and that cannot be achieved with any existing Sonoff device.

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