Lenox G20Q2E-50-2.
Furnace will not always respond to thermostat. When program is set to drop temp and then have furnace turn back on to heat house, the furnace does not activate (nothing- it's like it didn't received the message). When wife comes home from work, house is still cold.

I have replaced the thermostat to a basic honeywell programmable unit with same results.

The only way to get furnace to start back up is to turn off/on the master switch at the side of furnace. Then it works fine maintaining temps.

I am a homeowner, not an tech. Any help will be appreciated.