Cyngeo, I'm not sure if my answer is right but based on my observation. The first floor thermostat is the one that comes on and never the second floor. The aux. heat comes on when the temperature is going below 30 degrees outside (more or less on for about 2 to 3 minutes then off for about 12 minutes). When the temperatures hits below 20 then I see the aux. heat on most of the time.

Though all my ROI calcs were messed up a few nights ago when temperature outside dropped to -15, I didn't miss the aux heat, while the 2nd stage maintained a 70 setpoint. I am not too worry. My winter design is -6F. In February when ewt is lower a very cold night will fire up the aux.

Regards, Masoud

Connie,
You do want to verify your aux. heat size, I through the 10 K out as a ferinstance-not a given. check the paperwork that came with the equipment- for CM the aux. coils models are AGL5, AGL10 etc. with the number indicating the Kwh.
J