In an attempt to install a new thermostat for our heat pump, we failed to label the wires before removing old thermostat. How can we find out how to properly connect wires to the new thermostat. We have Concord outdoor unit (44407H097), Armstrong indoor unit (BCZ36A12A-1B). Our old thermostat is White-Rodgers (1F58-86), and our new thermostat is Honeywell 5-1-1 Day Programmable (RTH7400). Appreciate any help available.

Start by reading the sticky at the top of this forum. You will also need to read the manual that came with the new thermostat. Post back with any details that aren't clear.

You may need to go to your outside unit and see what wires go where, they should be connected to a printed circuit board with a letter at each terminal, make a note showing what color wire goes to what letter on the terminal board, this will be the same letter in the thermostat, now go to the air handler and make a note of which wire goes where same as outdoors (you should have a green "G" , a common "C" and a red "R" and a white "W2" the other wires will go outside and to the thermostat. Good luck.