i recently installed new heat pump early this year, my 92% condensing propane furnace is 8 years old.
it seems like everytime after running heat pump and then switch back to propane furnace first time, there is a dust burning smell for initial few minutes, and if next cycle is propane furnace, then no dust burning smell
and switching back from furnace to heat pump no dust smell either.
is this normal? or furnace or other component need service?
i normally change 3m air filter once every 3 months usage.