I have a Carrier Variable speed 2-stage furnace (58UHV) with a Carrier Thermidistat control that does support 2-stage heating. I just noticed that it's wired for only single-stage heating and I've been reading up on this to figure out why. It seems that in this configuration, the adaptive algorithm built into the furnace is handling the 2-stage heating. My question is, which is the more efficient method for handling the 2-stage heating: the adaptive algorithm or using the thermostat control?
Unfortunately, I only have an 8-wire bundle going to the thermostat and all the wires are being used. It was suggested that I could use one of the external temp sensor wires and just do without the temp readings, but I'm not so sure about that. The other option would be to run another wire (possible, but not easy). Would it be worth going through the trouble of doing this to control the 2-stage heating using the thermostat?