I have a digital Dometic thermostat and a Dometic AC with a Suburban furnace. I wanted to program the furnace so I could sleep cool and wake up warm, but Dometic said it couldn't be done. Since I didn't want to program the cooling, I left the Dometic connected to the AC but disconnected the blue thermostat wires and put a marr on each wire to isolate them, and ran new thermost wires from the furnace to the new Honeywell Programable mounted above the Dometiic. I was able to pull new wires through the wall so it looks like factory. It works great.