Ceiling fans can often be used to save money during the heating season. Most older homes have heating systems that are two to four times larger than they need to be. They also have blowers that operate at lower speeds. Being over-sized will cause the system to blow hotter air than it should, and run very short cycles. When the system blows hotter air, the hotter air tends to stay up at the ceiling. The lower blower speeds also contribute to this. Also, when furnace cycles are shorter, there are longer periods without any air circulation. If the air is not moving in a room and it is cold outside, the cold air that is at the wall, and windows will slide down off of them onto the floor. This will make the temperature on the floor much colder than higher in the room, and uncomfortable cold and drafty air will be felt. The colder the outdoor temperature gets, the colder the air at the floor level is going to be.
We checked the temperatures in a home that had a gas furnace that was two times larger than it should have been. This home was built in 1945 and had insulation blown in the walls and attic. The windows were replaced with energy efficient ones. The outdoor air temperature was 0°F (-18°C). We measured the air temperature in the room as soon as the furnace blower shut off: it was 86°F (30°C) at the ceiling, 70°F (21°C) five feet off the floor, and 63°F (17.2°C) 2 inches off the floor. Right before the furnace came on again, the temperature was 83°F (28.4°C) at the ceiling, 68.5°F (20.3°C) at 5 feet off the floor, and 58°F (14.5°C) 2 inches off the floor. With a heating system like this, the use of a ceiling fan will mix the air better, so the wasted overheating of the top of the room, where no one can feel it, is brought back down to the floor. The room will be a lot more comfortable, and you will be able to save money by turning the thermostat back a few degrees, while still feeling warmer.
With a geothermal heat pump, however, longer run cycles mean your room air is usually already being mixed well. We don't recommend running fans in the heating season in homes with geothermal heat pumps, unless you have someone come out and measure your temperatures at the floor and ceiling to see if it is necessary.