Will my 1 stage thermostat work with a 2 stage furnace?

Just had a new hi-eff furnace installed. They also installed a thermostat which I just found out is 1 stage. Today is -20C and my house does not reach the set temp of 23C. furnace works full-time , but only reaches 22C. I am thinking maybe it does not kick into 2nd stage? the fan is a DC variable speed, but I have a hard time telling that there is any change in speed during the heat cycle. Also, the discharge temp is a constant 110F, which is just a 35F gain. I would expect that it would go up for the 2nd tstage. OK, that's enough questions for just 10 points :)