The most common reason for short cycling is that the air filter is dirty and, therefore, non-functional. This is because the heat exchanger can retain heat to such an extent that it overheats. On the bright side, you will not have to look up “HVAC repair near me” as you can replace the filter on your own.
If your furnace shuts off after 15 minutes, a dirty air filter is likely blocking your heat. It's important to change dirty air filters at least every 90 days to avoid harmful debris build-up that obstructs your system's functions and distributes unhealthy air throughout your home.
If your air filter is too dirty, it will restrict airflow. Your furnace will then shut off early to avoid overheating. We encourage changing flat filters once a month, and pleated filters every three months. It's simple to stay on top of changing your filter by setting up a Filter Reminder on your thermostat.
Furnace Heating Cycle Run Time: Explained
Each furnace's “normal” heating cycle run time differs based on the size and type of furnace, your home's square footage, and the desired indoor temperature. Furnaces typically run for about 10 to 15 minutes in moderate weather. Extreme cold can result in longer cycle times.
While it should cycle throughout the day, clicking on too frequently may indicate a problem. Homeowners often find themselves wondering, "How often should my furnace cycle?" The answer lies in a gray area. On average, furnaces should kick on and turn off anywhere from three to eight times per hour.
This is commonly caused by a dirty air filter. Once high temperatures are reached within the equipment, the limit switch shuts down the heating cycle for safety reasons. Then the furnace must cool down before another cycle starts – but the issue just happens again.
With an effective air delivery system and a well-insulated home, this should be long enough to establish your preferred temperature throughout the building. After resting for approximately five to 10 minutes, your furnace will likely cycle on again.
If your furnace shuts off after a few minutes and starts more than eight times an hour, it may require repair. Common causes of furnace short cycling include restricted airflow, a malfunctioning flame sensor, or a poorly placed thermostat.
If your furnace turns on, and off, and back on again in a seemingly endless loop, you're experiencing short cycling. Essentially, short cycling occurs when the system cannot complete a full heating cycle. There's no one cause of short cycling, but with some troubleshooting you can get to the bottom of the issue.
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.
Short cycling is a common sign of a bad flame sensor. The sensor thinks that there isn't a flame, so it shuts off the gas as a safety mechanism. Except, there is a flame and without the gas to supply it, it dies. This is a frustrating problem, but an HVAC technician can fix it.
A clogged filter is one of the most likely reasons a furnace might shut itself off. If your filter is OK, contact a local pro. Remember, you can also set up Filter Reminders that'll let you know when it's time to change your filter. Check Air filters and filter reminders for detailed instructions.
A furnace cycling on and off repeatedly can be caused by various reasons, from dirty filters and obstructions in ducts and registers to incorrect thermostat settings and faulty limit switches. By following the steps above, you can help prevent your furnace from cycling too frequently and save energy costs.
The simple solution: Turn your furnace off and check the filter. If it's dirty or it's been 3 months or more since you changed it, put a new, high-quality filter in place.
The most common reason for short cycling is that the air filter is dirty and, therefore, non-functional.
They are designed to cycle on and off, but a standard home furnace should only turn on and off between three to eight times per hour. That means normal heating cycles last from seven to 20 minutes. You can tell your furnace is short-cycling if that on/off cycle happens every couple of minutes.
If the time between cycles is less than five minutes, the furnace is most likely short-cycling. Heating cycles that run for shorter periods of time produce more frequent heating cycles. Depending on the outside temperature and how well-insulated your home is, these short cycles may occur five to eight times per hour.
The most common problems that cause a furnace to short cycle include: An overheating heat exchanger. A dirty flame sensor rod. A blocked flue pipe.
Typically, a furnace should cycle three to eight times per hour. While furnace cycling is normal, frequent cycling can indicate that your heating is struggling to keep up. We've put together this guide to help you understand the difference between normal furnace cycling and short cycling.
Having a dirty air filter in your furnace can cause short cycling. While a faulty flame sensor will lead to an immediate shut-off, a dirty filter will allow your furnace to run for several minutes and then shut down. You might notice that the air being pumped out of the heat grates is significantly hotter than normal.