When a furnace frequently satisfies the thermostat and results in short cycling, it indicates that the system may be too powerful for the space it is heating. In this context, assessing the size of the furnace itself is crucial. An oversized furnace can produce heat more rapidly than the space can absorb it, causing the thermostat to reach the set temperature quickly and subsequently shut off the heating cycle. This leads to the system turning on and off frequently, rather than maintaining a steady temperature over a longer period.
Addressing this issue ensures that the furnace operates efficiently and maintains consistent heating. By evaluating the furnace's size, one can determine if it is appropriate for the heating load of the home. If necessary, adjustments can be made to either optimize the existing system or consider installation of a properly sized unit to improve overall comfort and efficiency.
The other options, while they might contribute to heating performance in different contexts (such as heat exchanger issues affecting efficiency, fuel type affecting combustion or cost, and a dirty air filter restricting airflow), do not directly address the issue of short cycling caused by the furnace's size. The primary concern in this scenario is the matchup between the furnace capacity and the space it is intended to heat.