We are down to a final decision on our home -- the thermostats.

- two 44k Carrier Performance-80 (58CTA series) dual stage burner, 3-speed blower furnaces
- two 3 ton 12 SEER Performance-12 A/C units w/ TXV's on the coils.

We are not using Infinity because our EnergyWise sizing for our ICF house states 40k furnaces and Infinity only come as small as 66K.

So, for t-stats it's now Infinity vs. Thermidistat Programmable. I know the benefits of the Infinity w/ an Infinity variable blower -- we can't have that. So, here's where I am confused...

The furnace talks about "ComfortFan" and how it "lets you control fan speed during continuous fan operation with the thermostat." But, the Thermidistat fan control is 'on/off/auto.' The Infinity fan control is 'low/med/hi/off/auto'

So does ComfortFan work with either t-stat, and if so how?

And if it works with a Thermidistat, then is an Infinity just overkill dollars to use w/ a 58CTA?