Well, I’m sorry to hear about the problems you’re having. One of the things you should understand is that the nest thermostats only draw about 70 mA a power to maintain the batteries fully charged in the operating system for the thermostat. Now one of the things that is back plate has our pressure contact, so make sure the wires are very clean, copper, inserted properly all the way to ensure a good contact. Internal to the nest display are a number of what they call. Micro relays. When there’s a call for heating or cooling, the micro relay for heating will engage and connect the power coming in on the R wire to the W wire to send that current back to the control board to signal turning on the heat. This process loses very very little current if any at all. When the display is mounted on the back plate, there’s no way for you to verify the voltage so you have to be checking the voltage at your HVAC control unit . You would set your meter to measure AC voltage, tell the thermostat to turn on say heating, go to your HVAC furnace unit and the control board inside, and measure the voltage between the C terminal and the W terminal. Add between to see terminal and The R terminal. Compare the two voltages and see how much is being lost.
The AC Cooling Wizard
NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
