My hunter thermostat model 47110A is set to 20 degrees celsius but the furnace will not stay on long enough for the temperature to rise to the set degree. It is currently holding at 16 degrees instead. The batteries are brand new but still the temperature will not rise.
This is my first home so any tips or suggestions would be great.

Thank you

We need the model number and brand of furnace,, could be you need to clean the flame senser, but if its electric you won`t find one,, more info please

Lenox ml180h series