My oil heat furnace was functioning normally on an old mercury switch thermostat, but I wanted to replace it with a programmable Honeywell 5+2 one. There were Y, W, G, R, and B wires screwed in on the old stat (see photo underneath, I took one after most of the wires were off but I assure you they were correctly labeled). The system does NOT cool. Maybe at one point it was hooked up to something, but it does not cool and there is no heat pump.
I wired up the thermostat according to the directions, but the blower fan would not turn off. I then read in the instructions that I should not connect the "B" wire, so I took that off, but the blower fan continued to run on "auto", and would turn off when I turned the fan to "on."
Any idea what's going on? I'm almost thinking the new thermostat may be defective, or I'm defective and can't figure out a basic wiring diagram.
This is the old thermostat wiring, with everything tagged correctly except for the B wire which I was yet to take off.
Sorry the photo of the furnace wiring is so bad. It's in a half basement and it's very dark.