Why Does My Furnace Keep Turning On and Off?

When your furnace is working properly, it automatically cycles on when it senses that the air is too cold. When the temperature in your Arlington, VA home or business is comfortable, the heating system shuts itself off in response. The process is so automatic that you probably don’t give it much thought. However, it could indicate a serious problem when your furnace keeps turning on and off randomly throughout the day. Fortunately, there are some troubleshooting tips you can try on your own before placing a call to Brennan’s Heating & Air Conditioning for repairs.

Diagnosing the Problem

When a furnace keeps turning on and off, it is usually due to short cycling. This is the term used to describe problems originating from within the heating system. If short cycling is not promptly diagnosed and corrected, it could cause permanent damage to your heating unit and higher utility bills. The average heating system cycles on and off three to six times every hour. To diagnose a problem with short cycling, our technicians run a test cycle of your heating unit and count how many times it stops and restarts over 60 minutes.

Pay Attention to Your Air Filters

One of the most common causes of short cycling is also the easiest to fix. If you don’t make a habit to regularly clean or change your heating system’s air filter, it could have a major impact on its efficiency. Warm air can’t pass through the filter and it backs up within the unit. This sends the incorrect message to the heating system that your home is already warm enough. The unit subsequently shuts itself off and your home becomes cold, signaling the system to start up again. To avoid this problem, make sure that you change the air filter at the start of each new season and check it monthly.

Check Your Thermostat

Sometimes the problem of short cycling is caused by a faulty thermostat and not by the unit itself. You should ensure that your thermostat is turned on and set to the accurate settings before assuming that your heating unit needs to be repaired. The placement of your thermostat also makes a difference. If it is too close to another heat source, such as direct sunlight or a heat register, it could sense that the temperature in your home is too warm. Your heating system will turn off when this happens.

Other Possible Causes of Short Cycling

If you’ve ruled out a dirty air filter or a malfunctioning thermostat, the problem may be caused by one of the following:

• Corroded flame sensor
• Improperly sized heating system
• Foreign objects lodged in the chimney or air vents

If you suspect any one of these issues, schedule an appointment with an experienced HVAC professional at Brennan’s Heating & Air Conditioning.  We are proud to serve our friends and neighbors in Arlington, VA and the surrounding communities.