Switching over from Weathertron Baystat240 to Hunter 44760. Current wiring on Baystat is:

R: Red
T: Brown
O: Orange
G: Green
Y: Yellow
X2: Vacant
B: Blue
W: (jumpered to U): White
F: Black

According to the Hunter installation manual, wiring on the new thermostat will be:

R: Red
Y: Yellow
W2: White
O: Orange
G: Green
C: Blue

Where do the brown (T) and black (F) wires go?

Thanks much!

-- steve --

Usually there is a 24 volt AC transformer in the furnace with the secondary winding connected to a red wire running to the thermostat and a blue wire, common, to the gas valve, A/C relay, and fan relay. From the thermostat there will be white wire to the gas valve, yellow to the A/C, and green to the fan. The thermostat is wired to switch the power from the red to the white, yellow, and green as needed with the blue completing the circuit. Most thermostats and furnaces have the contacts labeled R, B or C, W, Y, and G for the corresponding wire colors. It may be wired to have the A/C control wires return to the furnace and its controls and then a second wire goes to the A/C unit. Internal wiring may replace the green wire if the thermostat does not give you the option of fan only or continuous fan. Digital or programmable thermostats may need the blue wire connected to them.

In order to connect the brown and black, you must identify their function. If you don't have any documentation on the Baystat, you might check their website. Another alternative is too try to figure out what they are connected to at the furnace. If you have an ohm meter, you may be able to measure which functions they connect to the red wire on the old thermostat. As a last desperate measure, connect up what you have and see what doesn't work. The red and blue should be the hot wires, and as long as they are connected correctly, you shouldn't hurt anything.

Labman, for your quick response. You don't know where I can find a wiring diagram for the Weathertron Baystat240, do you? I'm told it was a GE product, but can't find anything on their website that even indicates so. Thanks again!