Ecobee blacks out and becomes unresponsive, causing the house to lose heat!
We had to switch to a battery-powered, backup thermostat to get the heat back on, as it’s still winter.
This is a single stage system, so Rh and Rc are jumpered together.
Technical support staff had me “dry contact”/connect red and white wires together to start the HVAC heat, and monitor for ~20min to see if the HVAC as the issue. The heat remained on for the whole time, with blue flames visible through the HVAC slits and fan blowing heat, so we ruled this out.
Next, I was to make a video showing how the wires are connected in the baseplate, and more importantly, to demonstrate how the ecobee will black out after ~10minutes of being connected to the baseplate and that this was independent of whether the fan/heat was running. To do this, first made sure the house was at 76F, which is well above the set point of 72F, ensuring heating doesn’t get triggered.
03:00 – connected ecobee to baseplate
04:34 – shows HVAC is not running (current temp 76F, set temp 72F)
14:40 – ecobee blacks out
16:19 – confirm voltage (28V) still between C & R in baseplate wires