Heat will not turn on.

[nicholasvonryan]

This is our third or fourth year with our Nest. We set it to heat and nothing is happening other than the Nest reports that it will reach the temp in X amount of hours depending on the temp setting. I tried resetting it and still have the same issue. I tried diagnosing the equipment. I powered down everything and disconnected the W1 wire at the furnace. Powered everything back up and the Nest still saying that the heat is connected. I then disconnected at the Nest end. Once the Nest powered back up it said there was a configuration change. I powered the Nest back down and reconnected the wire behind the Nest, the W1 while still having it disconnected at the furnace.  The Nest again said that the heat was connected. I went ahead and powered it down again and reconnected the furnace. 

The blower works. I cannot test the AC since it is too cold outside. 

[Patrick_Caezza]

@nicholasvonryan 

All thermostats that use the 24Vac interface (including the NEST) are just one-way. When a thermostat calls for heat, it closes an internal relay, which tells the HVAC to turn the heat on. It's that simple.

To check if the problem is with the thermostat or the HVAC, turn the power off and then take the G (green), R (red), and W (white) wires and twist them together. Turn the power back on, and the heat and blower should turn on. If they don't turn on, then the problem is with the HVAC unit.