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View Full Version : Wiring from White rodgers mercury switch thermostat to 5 wire Honeywell RTH 110B


fbailin
Jan 13, 2009, 05:17 PM
Trying to get the new Honeywell Digital thermostat RTH 110B to work both in heating and cooling modes.

5 wire installation from old White rdogers thermostat.
Wire colors are G Y W R Br.

Have to switch the R wire with the Br wire to get fan oeprating or A/C.

Then have to switch them back to get Heating unit to work.

Honeywell proivides a small "u" shaped jumper for use in 4 wire connections but this a 5 wire connection.

Thermostat temps seems to be okay.

Thanks in advance for any assistance.
F Bailin

wmproop
Jan 13, 2009, 05:26 PM
Go to your furnace,, see what the brown wire is attached to,, also would helo to know the brand, and model number of your furnace,, and more info as to what the stat wires are connected to in furnace,, break down each wire and color

KC13
Jan 13, 2009, 05:32 PM
Sounds like you have a 2 transformer system. The wire that caused the heat to work should connect to Rh, the other to Rc, with the jumper removed.

hvac1000
Jan 13, 2009, 06:08 PM
If all else fails post the EXACT model number of your old thermostat.