I just noticed my existing wire bundle going to the thermostat has 4 wires
but I am having a new variable speed two stage furnace (Trane XV80)
installed with the existing one stage condenser. I looked in the Honeywell
VisionPro thermostate install guide and it looks like I might need at least
5 or 6 wires. The installer will discover whatever needs to be done, but
just wondering ahead of time if they will have to replace this wire because
it goes through some tricky wall sections.