Ok, getting really frustrated because nothing is working and I've spent a lot of time on this.
I was going to wire it to the furnace, but there is no C terminal there. I have a W R Y T and G. I tried measuring across the terminals to get 24V but was getting 65-72 volts. So I hooked up my extrenal transformer, fished another wire with a lot of difficulty, hooked the C on the external transformer to the C on the thermostat, hooked the R on transformer to the RC (jumpered to RH) on thermostat, and still no power.
I measured the voltage of the 24VAC transformer and my multimeter says it's putting out 65V. I'm thinking my multimeter (1 month old, only used one other time, but a Radio Shack piece of garbage) might be off to get two 65V readings when they're supposed to be 24V, but I still get no power to the thermostat.
Now the thing won't even turn on with batteries. Maybe it was 65V and blew something?