Furnace wont' ignite when turn on heat
You should be getting 24-volts +- back from the thermostat to the furnace on the white wire.  If you are not getting this, the thermostat in not really calling for heat. Jumper from the red wire on your furnace to the white wire at the furnace.  the furnace should start.  This is fairly technical stuff. You may want to consult a pro.