If you’ve been wondering, "Why does my heater keep turning off" you’re not alone. Many homeowners face this common issue which can lead to higher utility bills or costly repairs if not addressed quickly. A furnace that frequently turns off and on, a condition known as furnace short cycling, could be a sign of underlying issues that need immediate attention. Here are some of the most common reasons why your furnace keeps turning off:

1. Low airflow.

One of the most common causes of a furnace shutting off unexpectedly is low airflow. If your furnace keeps turning off, check for issues such as:

• Dirty Air Filters. A clogged filter restricts airflow, causing the furnace to overheat. Replace air filters every 60 to 90 days to prevent this problem.
• Dirty Blower Wheel. Dirt on the blower wheel can reduce efficiency, causing the furnace to short cycle. Regular maintenance can help avoid this issue.
• Closed or Blocked Air Supply Vents. Closed or blocked vents limit airflow, causing overheating. Make sure all vents are open, even in rooms you don’t use, to prevent your furnace from shutting off prematurely.

2. Faulty thermostat.

If your furnace keeps turning off and on, your thermostat may be the culprit. A malfunctioning or improperly placed thermostat can cause your furnace to short cycle. Common issues include:

• Old wiring or dead batteries: Replace batteries or old wiring to ensure accurate temperature readings.
• Thermostat location: If your thermostat is too close to a heat source (like sunlight or a heat register), it can misread the temperature and cause your furnace to keep shutting off. In this case, relocating the thermostat might be necessary.

3. Dirty or corroded flame sensor.

A dirty or corroded flame sensor can cause your furnace to keep shutting off unexpectedly. The flame sensor detects if the furnace's burner is lit, and if it doesn't register the flame, it will shut off the gas valve to prevent a gas leak. If the sensor is dirty, it may fail to detect the flame, causing your furnace to shut down. A professional HVAC technician should clean or replace the sensor if needed.

Additional causes for furnace short cycling.

If you’ve tried the above solutions and your furnace keeps turning off, consider these additional potential issues:

• Blower motor issues: The blower motor circulates air through your home. If the motor is faulty, it could cause the furnace to shut off.
• Blocked flue pipe: A blocked flue pipe can prevent exhaust gasses from escaping, causing the furnace to overheat and shut off.
• Oversized furnace: If your furnace is too large for your home, it may heat the space too quickly and shut off abruptly, leading to short cycling. This requires professional assessment and possibly replacing the furnace with a properly sized unit.

Don’t ignore a short cycling furnace!

If your furnace keeps shutting off, it’s crucial to address the issue immediately. Ignoring the problem could lead to expensive heater repairs or even a full system replacement. Scheduling regular maintenance and a professional tune-up at least once a year can prevent many common furnace issues, including short cycling.

For more information on why your furnace keeps turning off or to schedule a service call, contact your local HVAC pros at Petro Home Services. Our team of HVAC experts is ready to help you keep your heating system running efficiently, so your home stays warm all winter long.