2nd stage should kick in any time you bump up the temp a couple of degrees.
Is the set up menu set right?
#170 to 8
They wire up W2 at both t-stat and furnace?
Yes on the #170, and swapped TStats in process of elimination. Hopefully just a wiring problem on the furnace controller board. I'm just testing my system to make sure everything is running right. The installer will be here next week to fix it.
BTW, here is a response from Honeywell when I asked them how to get the RTH7400 to make a stage 2 call:
The algorithm inside the thermostat works on proportional and integral control. Please increase the set temperature by 5 to 6 degrees and the thermostat can call for the auxiliary heat. As mentioned earlier, the thermostat will not show any indication of calling for second stage of heating.
I'd be interested in learning more about "proportional and integral control".