Why Does My Furnace Keep Turning On And Off?

Properly sized residential furnaces typically cycle on and off between three and eight times each hour. If the weather is freezing or extra insulation is needed, the furnace may cycle on and off more frequently. Short cycling is what HVAC specialists call it when a furnace turns off and on too often. Short cycling is usually associated with the safety measures of a furnace, which shuts it off when it determines that the surrounding environment is too unsafe for continued operation. If you ignore the issue, it could eventually lead to a complete breakdown, a rise in your monthly energy costs, and the failure of crucial safety features. You can tell if the problem with your furnace is simple enough to solve or if you need to call in the pros with some basic troubleshooting.

Dirty Air Filter

A dirty air filter is a common culprit in a furnace that cycles on and off too frequently. Filters effectively remove contaminants from the air. The filter becomes clogged with time, reducing the amount of air that may reach the heat exchanger. The high-limit switch trips, and the furnace shuts off when the heat exchanger overheats. To avoid this issue in the future, change the air filter every 30 days.

Air Supply Vents closed

Cutting down airflow from your home by covering vents is not an effective way to reduce energy consumption. Instead, it makes your furnace work harder than it has to because it restricts airflow and slows the blower down.

Thermostat Problems

If the thermostat's batteries die, they may malfunction. If the thermostat is outdated and new batteries don't help, it could be time to get a new one. Placing a thermostat in bright sunlight, next to a heat register, or near another heat source might also trigger the furnace to cycle frequently. A professional HVAC technician will have suggestions on where to put a new thermostat. The solution is to repair or replace the thermostat or move it to a different location.

Limit Switching Troubleshooting

If the gas furnace's exhaust flue is clogged, the high-limit switch will shut it off. Incorrect operation of the switch allows for a buildup of heat and combustion byproducts inside the appliance. The unit's effectiveness will suffer, and the situation could become dangerous. If a furnace becomes too hot or blocked, a high-limit switch will shut it down. The switch's functionality could be improved by replacing the furnace's air filter and cleaning the blower motor.

When Should You Call an HVAC Professional?

The furnace is too big for your home: Your home's size is too large for the furnace: However, one cannot always assume that larger is better. If the capacity of your furnace does not meet your home's heating needs, it will heat up rapidly, shut down, and start the cycle again—the constant cycling results in unnecessary wear and wastes energy. If your current furnace is too small for your home, the only solution is to have a professional HVAC technician measure your space and install a new, appropriately sized unit. It's possible that a labor warranty will cover these expenses for newer pieces of machinery.

Dirty sensor rods: Sensor rods in gas furnaces are responsible for detecting the flames in the burners, and a dirty rod can fail this function. Not sensing a flame will result in the gas valve being shut off and the furnace is turned off. Because of the soot, a sensor rod may be unable to detect the fire.

Dirty blower wheel: Blowers that haven't been cleaned and oiled regularly will experience a reduction in their speed due to the dust that builds up on their wheels. If this happens, a furnace's airflow over the heat exchanger will be reduced.

If your furnace keeps cycling, you can learn a lot about what's causing the problem by DIY furnace troubleshooting. If you are unable to fix the issue on your own, you must contact a professional HVAC technician without delay to prevent the possibility of your furnace failing when temperatures drop. Get in touch with Best Owner Direct HVAC to schedule an appointment or if you have any questions about making your furnace function as energy efficiently as possible.