Greetings! I recently purchased a house that is equipped with an old York thermostat (the kind with mercury vials in it). I was attempting to change it for the Honeywell RTH9580 Wifi thermostat but ran into some problems with the wiring. These are the wires that I have on the old thermostat: W, C, Y, B, G, R and X The options for the new thermostat are: C, K, Rc, R, W - O/B, Y, G, W2-aux/E, Y2, L Since I have both a C and B wire I am at a loss. I also don't know what to do with the X wire. Any help would be greatly appreciated. The setup is a heat pump with an Oil Furnace. -Gary

Hi guys, I'm trying to figure out proper connection to use as a main heat source my recently installed Harman XXV stove and as a backup heat source a dual stage or modulating propane furnace. Furnace should work in case stove is failed in some reason or in case of extended home leave. I'd like to use either Honeywell Prestige IAQ YTHX9421R5101WG (THX9421R5021WG with THM5421R1021) or VisionPRO 8000 (TH8321R1001/U with or without with THM5421R1021) with RedLINK thermostats (have both). I always can install two separate thermostats one for stove and another for furnace/AC but prefer to use one for simplicity of control. In the summer time thermostat suppose to control dual stage AC unit for cooling and dehumidification with and automatic changeover between heat and cold. I don't yet have make/model number for furnace/AC units but assume they should be a standard higher end units compatible with standard thermostats (not branded RS485 communicating thermostats). Extra 24VAC power or relays in case it necessary is not a problem. I guess Prestige IAQ (latest or older model) with EIM module should be capable for this task as well as a new RedLINK VisionPRO 8000 either stand alone or with EIM. I might as well try to control pellet stove as a dual stage device with an extra relays and resistors connected either in parallel or series with the stove temperature sensor (NTC thermistor). I know it's a strange setup :~) but I think it's possible and would appreciate any help with proper connection. Thanks