Just had GMS80804BX residential heater installed. Technician said he could not connect Fan only operation from Lux1000 thermostat as there was only a 2 wire (red/white) connection between heater and Lux. I ran a 6 wire (future AC if needed) to heater and connected the red/white wires. Heater works fine. Don't know how/where to connect the wire (what color?) between units to manually switch on heater fan during hot weather.

Ken