If you do not have C terminal on your HVAC board you can purchase a 24-volt power adapter to power your thermostat. Install at your own risk.
TheSimple does not take responsibility for thermostats that are wired improperly. Improper wiring can cause unwanted permanent damage to the thermostat. We always recommend professional installation.
You will need to plug the 24-volt power adapter wires into the C and RH terminal. Next, you will need to use a voltmeter to measure the voltage between either the "W/E and C" or "Y and C." The expected reading should be close to 0 (zero). If you find reading between 30 to 50 volts, then you will need to switch the wires you plugged into C and RH. Then measure the "W/E and C" or "Y and C" again for close to 0 (zero) voltage.