I recently moved into a new home and wanted to replace the old thermostats with digital Honeywell ones. From what I understand the home has a Rheem 10 Seer (1996) compressor and a Williams oil furnace installed in 2012 (not sure of the exact model). The system is zoned via dampers with a master thermostat downstairs (this one can switch between heat/cool and fan on/off) and a secondary thermostat upstairs (just temperature control on this one).
My problem is that I can't figure out why my main thermostat has a B and an O wires. Full list of wires with labels:
- B - black wire
- O - orange wire
- G - green wire
- Rc + Rh (via jumper) - red wire
- Y - yellow wire
- W - white wire
Master thermostat picture:
The secondary thermostat is even stranger with what seems to be incorrect labels/wire colors. It has three wires with what seems to be labeled like this:
- W/Heat - white wire
- R/Com - red wire
- B/Cool - green wire
Secondary thermostat picture:
Instructions page from the new thermostat for conventional systems:
Which wires would I connect these on the Honeywell thermostat, and which settings should I choose in the setup?
UPDATE: I called Honeywell's help line and they redirected me to a zoned help line (800-828-8367 option #5). There a very knowledgable sounding person told me that my thermostat is not compatible with zoned systems. He said that the B and O wires here are used for controlling the dampers in the ducts. His recommendation was to get a RTH2410 or RTH2510 (newest models with no screws on front plate). The manuals for these suggest that they do accept B and O wires in non-heat pump situations.