I have a heat-only natural gas furnace with a fan. (Bryant 315aav036070adja) The thermostat I'm trying to install is a Honeywell TH4110U2005/U.
My old thermostat only has two wires (V+ and Vg), which go to a controller panel by the furnace which sends Rc, W/W1, G, C, and Y1 to the furnace. There's also a green wire through the wall that doesn't connect to anything on either end.
The installation instructions for the Honeywell say:
Rc [R+Rc joined by Slider Tab]
C 24VAC common
Can I simply disconnect the V+ and Vg wires from the control panel, and connect them to whichever wires correspond to power and heat (then do the same thing with the unused green wire to whichever wire corresponds to the fan)? How do I figure out which of the output wires in the control box are for heat/power/fan?
Control Panel Wiring Guide: