The furnace has a 2-stage gas valve. On the low stage it is burning less propane and providing less heat. Longer run times are expected. The furnace should not be consuming more propane.

its on the lower setting because the higher setting blew full for e cold air.

The air on the high setting should not be cold. You need the installer to come back and fix the problem. I suspect this is an installation error and not a problem with the equipment.

Nest now displays indoor temp 1 to 2 degrees warmer indoor temp than it actually

Did you install a new thermostat? A one degree variation between thermostats is common. Most of the time the display is rounded up or down depending on what the thermostat is doing.

Same thermostat as before. the installer is my son. he thought the air on high was fine. i thought it was much cooler than the high air our old furnace blew so he turned it down. the old furnace blew high air and was warm. new blew high air and is cool. the lower setting is much warmer air, i was just concerned about the amount of time the nest history shows the furnace in use versus the old one.

Ask your son to check the temperature rise of the furnace on low and high stages. The installation manual will specify the acceptable ranges. It could a simple fix of lowering the blower speed. I would also check the gas valve is actually firing up properly in the second stage.

If the air is cooler than your old furnace, then you might be feeling a wind chill affect. You are raising the thermostat a 1-2 degrees to compensate for the difference in comfort. This is another reason he should check the temperature rise.

Monitor the amount of propane you are using and compare to the same period last year.

Thank you. he did lower the blower speed and that is what made the heat come out warmer. ill have him check the gas valve. My main concern was whether or not a new Goodman high efficiency furnace should run more (which he tells me is fine). ill also monitor the propane levels. thank you.

Is your son licensed?

no license needed in NH to do HVAC, but he does has a gas license and has been in hvac field as an installer for a larger company for a few years. also currently in plumbing school.

OK, he should be able to figure it out then.

It appears he didn't the first time.