A typical furnace run time is between 10 and 15 minutes. Although some models may run for as long as 20 minutes at a time. If you notice your furnace running for longer than 20 minutes each cycle, this may be a sign it's working overtime to heat your home.
Furnace short-cycling refers to a furnace that's switching itself on and off too frequently. It's normal for a furnace to turn on and off periodically. 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.
With all that being said, if there are no extreme factors involved, the average run time for a furnace is 10-15 minutes per cycle. Your furnace may need to run two to three times an hour to maintain your desired temperature if your home has average insulation.
3- Furnace Shuts Off After 15 Minutes Due to a Dirty Air Filter. If your furnace shuts off after 15 minutes, a dirty air filter is likely blocking your heat.
HVAC maintenance companies explain that a furnace will normally perform an average of two to three cycles in an hour, with each cycle lasting 10 to 15 minutes. But to keep temperatures at a comfortable level during cold weather, a furnace might need to increase this range to three to 10 cycles.
Running your furnace constantly can put extra strain on the system, potentially shortening its lifespan. It is important to have your furnace regularly maintained to ensure it is in good working condition and not being damaged by constant use.
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.
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.
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.
Under normal conditions, your furnace should run two to three heating cycles each hour, with each cycle lasting for 10 to 15 minutes. It may run longer or more frequently during extremely cold weather when the outdoor temperature is below zero, but it still should only run sometimes.
Most furnaces kick on and off between three to eight times an hour, depending on things like outdoor air temperatures, the furnace's age, and how much insulation you have. That's why, instead of asking how often a furnace should cycle, it's best to stay alert to changes in how your furnace is running.
But in general, your furnace should not constantly be running. Otherwise, it could indicate a problem with your heating system. In this case, have a qualified HVAC (Heat, Ventilation, and Air Conditioning) technician inspect your system and address issues that make it run constantly.
However, the average flame runtime in a furnace is about 10 to 15 minutes per cycle.
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.
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.
A high-efficiency furnace should be running at least 80% of the day if not longer.
Most furnace flame sensors cost less than $20, but if you opt to have a professional HVAC technician make the repair, you can expect to pay between $75 and $250. Need help replacing your flame sensor?
A furnace limit switch is a component of a forced-air furnace that is responsible for turning on the furnace blower once the desired heat has been met inside the furnace. Without a functioning furnace limit switch, a furnace would not be able to regulate the temperature in conjunction with a thermostat.
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 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.
Average Heating Cycle Length
If your furnace is well maintained and working properly, it will typically perform two to three heating cycles per hour with each cycle lasting for around 10 to 15 minutes.
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. Turn the furnace on again.