I have an oil heater. We have been having problems with the thermostat or heater. If we turn on the switch on the heater and leave the thermostat on the lowest setting, the 2nd floor gets very hot. The base board radiators down stairs did not get hot at all until we pushed the thermostat up, and the heater runs about every 20 minutes. We just replaced the thermostat with a digital one. We had it set on 68 and in the morning, woke up to a reading of 90. How can we correct this problem without turning off the main switch during the day or night.

Did this problem exist before the new thermostat? What kind of control ststem do you have on your unit. Pump,zone valve, gravity etc.