This November proved to be very demanding on our heating equipment. With extreme temperatures some furnaces run almost continuously. This is not indicative of a furnace problem but rather of a heat loss problem with the house.
Most older homes were built with no insulation or very little. A typical Chicago bungalow or brick apartment building might have walls that are 12″ thick but they have no insulation. On sub zero nights some of the inside walls are literally ice cold. There is a direct correlation between the energy efficiency (tightness) of your home and the frequency and duration of cycling of the furnace.
Poorly insulated homes lose the heat quicker than the heating system can replenish it. That is why it is so important to tighten up your house with weather stripping and having at least R-38 attic insulation. If your furnace can’t satisfy the thermostat stetting then you may have a mechanical issue or a sizing problem with the equipment.
If you are using a programmable thermostat do not drop the nighttime temperature too much otherwise it may take several hours to bring it back to normal. When the outside temperatures rise back to the upper twenties and thirties then you can resume your normal set back temperatures.