Why Your Furnace Keeps Turning On and Off

Frequent cycling of the furnace (in several minutes) means that there is a furnace short cycle problem. Furnaces do run in cycles; however, repeated programming and cycling may signify a problem that requires troubleshooting from an HVAC company. Short cycling can cause your home to be warm and humid, drive up energy bills, and cause undue stress on the furnace’s elements.

Should you discover your furnace short cycling without any cause, you can either try to solve the problem yourself or hire some professional assistance.

How Often Should a Furnace Normally Turn On and Off?

There is no need for the furnace to work continuously for maintaining the comfortable indoor temperature. Normally, however, several 10-15-minute cycles would occur in an hour.

Furnace short cycling is distinguishable from the usual cycling because the furnace:

  • Switches on for a short period of time only, usually a few minutes.

    • The unit shuts off prematurely if it is not able to adequately heat the home.

    • Restarts shortly afterward.

    • Repeats this pattern frequently.

    This may be recurring; if so, it is worth investigating.

    Why Does a Furnace Keep Turning On and Off?

    The reason for identifying the root cause of the issue is that not all issues are solvable. Some are easy to resolve, while others are not.

    Common furnace short cycling causes include:

  • A blocked air filter: The air filter which is blocked will not allow air to reach the furnace, thus causing the furnace to overheat.

    • Problems with thermostats: There are a variety of reasons why the thermostat can malfunction, including wrong installation, insufficient battery charge, poor calibration, or wrong placement of the thermostat.

    • The oversized furnace: This furnace is too large to heat the room properly to the target temperature.

    • Clogged Flame Sensor: If the flame inside the burner is not working properly, the furnace will be switched off as a safety measure.

    • A failed limit switch: This safety device can provide the wrong signal about the furnace being too hot.

    • Electrical or mechanical failures: If some components of the furnace start malfunctioning, they can interrupt furnace operation.

    What Problems Can Frequent Furnace Cycling Cause?

    Short cycling isn’t simply an annoyance. Cycling the furnace puts undue strain on system components and wastes energy.

    Frequent cycling can cause:

  • Higher heating bills

    • Temperatures in the house are not even from one place to another

    • Damaged blower and ignition components.

    • More frequent repairs

    • Reduced furnace lifespan

    • Potential damage to important internal components

    If overheating or another major problem is to blame and if the furnace continues to be used without the problem being addressed, it will become worse.

    What Can You Check Yourself When a Furnace Keeps Cycling?

    There are some basic checks and furnace maintenance that homeowners can do prior to hiring a tech.

    Check the following:

  • Check the air filter.

    • Check your vents.

    • Check the temperature on the thermostat.

    • Consider thermostat location.

    • Be on the lookout for sounds not normally heard.

    It is recommended by ENERGY STAR to replace furnace filters if they are dirty, at least once a month when there is a lot of usage of the furnace.

    When Does Frequent Furnace Cycling Require Professional Repair?

    43% of heating and cooling capacity is lost to defects and other installation issues. A technician could look into safety controls, airflow, flame sensor, and burner assembly, as well as furnace sizing.

    Should you have any of the following problems, professional assistance would be needed:

  • The odor of burning/ a gas smell.

    • Signs of overheating

    • Repeated ignition failures

    • Unusual or loud mechanical noises

    • Electrical problems
    • A furnace that repeatedly shuts down and won’t maintain the set temperature

    Avoid operating a furnace to override the safety controls. These components are for the protection of equipment and occupants.

    How Can You Prevent Your Furnace From Short Cycling?

    Maintaining the furnace properly will help you avoid any potential problems and detect the problem at an early stage.

    Maintaining a furnace by doing the following:

  • Frequently replace or clean the air filter.

    • Maintain freedom of ventilation with supply and return vents.

    • Have furnace professional care carried out once a year.

    • Make looking at and clean the area around the furnace.

    • Be aware of changes in cycling circulation.

    • React to unusual noises, odors, and performance issues in a timely manner.

    • Get furnace professionally sized when replacing an old furnace.

    Preventive maintenance from a professional company such as Sunny Appliance Repair is critical in this respect, as a small issue with the airflow or maintenance may become a serious equipment issue.

    Conclusion

    Your furnace may be experiencing cycling on and off, meaning that it is short cycling and requires fixing. The cause could be either a dirty filter, blockage in the vent, or a variety of other issues such as the thermostat, oversized furnace, safety control, and mechanical failure.

    When the furnace cycles continuously every few minutes, schedule a service call for the furnace rather than the continuous cycle and reset.