I have an old American Standard gas furnace that the burners continue burning on even after the heat reaches the desired setting on the thermostat. If I turn the furnace to the pilot setting the burners go off, If I turn it back on the burners come on even if it is 80 degrees in the room and the thermostat is turned back as far as it will go. I thought it might be the thermostat so I changed it and still get the same results.