What can cause a gas furnace to short cycle?

Short cycling in a gas furnace refers to the situation where the furnace frequently turns on and off in quick succession instead of running for longer, more efficient cycles. One primary cause of this issue is related to problems with the thermostat or improper sizing of the furnace. If the thermostat is malfunctioning, it may inaccurately read the temperature, leading to the furnace shutting off before the home has reached the desired warmth. Similarly, if the furnace is improperly sized—either too large or too small for the heating needs of the home—it can lead to rapid cycling because a unit that is too powerful will heat the space too quickly, causing the thermostat to signal for it to shut off prematurely.

Identifying these thermostat issues or sizing problems is essential for ensuring the furnace operates efficiently and maintains a comfortable indoor environment. Proper diagnostics and adjustments, such as recalibrating the thermostat or resizing the furnace, may be necessary to resolve the issue.