How to verify the correct functioning of a varible speed air handler

I'm listening as well.

I have a Maytag 2 stage 100btu furnace w/ variable speed. Amana and Maytag may be the same mfg, Nordyne, I can't recall. I have a 1700 sqr ft ranch home with about 1200 sqr ft in the basement. So I"m trying to heat about 3000 sqr ft.

In my case, the hvac person just installed a timer/switch that runs the furnace on "low" for 1 to 10 minutes before it kicks into "high". The timer setting is manual. This is the "two stage". Essentially 3 burners are low and 5 burners are high.

The low/high settings appear to be controlled on the blower. He popped the cover and put me at the 2nd to last setting. I leave the "fan only" setting on 24x7 which keeps it running on the low speed.

It would be really nice to know what the >Is there a way for an amateur to verify the correct functioning of a