i need help. i have a tappon furnace (if anyone needs more info i can look it up) I just changed thermostat cause that was cheap to fix and thought it might be problem, but not. The furnace does not stay consistantly runny. If i turn power or thermostat on/off it will come on and runn and perodically it turns on and runs normally, but problem is thermostat is set at 72 and never runs long enough to reach over 68??? I do not know what to do next, please help!