On average, a furnace will cycle every 10 to 20 minutes. The amount of time between cycles is dependent on a number of factors, including the outside air temperature and the temperature at which the thermostat is set.
It is normal for a furnace to cycle on and off anywhere from three to 10 times in an hour. If, however, the furnace is randomly shutting off and on or the cycling seems off, there are some troubleshooting tips a homeowner can try before calling in a professional.
- Check the air filters - if the air filters are dirty, the air from the furnace cannot pass through efficiently. This can cause erratic cycling. Check to ensure the filters are clean and, if necessary, replace them with new ones
- Check the thermostat - if the thermostat is not set at the correct temperature, that may be a cause of short cycling. In general, summertime temperatures should be set at 78 degrees Fahrenheit, and winter temperatures at 70 for maximum efficiency. If it is a digital thermostat, try replacing the batteries
- Rule out other problems - if the filters are clean and the thermostat is fine, there may be some other underlying issues. The home could have a heating system that is too small, for example, or there could be debris blocking the chimney or air vents