My friend wants me to install a programable thermostat for him. The
unit is a Coleman heat
pump model 3736-811 with a gas furnace. The t-stat is a Honeywell RTH
7500.

The connections on the old t-stat are W2-grey wire, G-green, R-red,
L-white, X-black,
O-orange, Y-yellow, B-blue.

The problem is that there is no C wire on the old t-stat.

Any help would be appreciated.

lobo