As stated by the National Fire Protection Association (NFPA),
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.
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.
Reasons why your furnace keeps turning on and off:
Temperatures outside of home. Improper insulation. Faulty thermostat. Dirty flame sensor.
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.
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.
If the flame sensor fails, your furnace may not be able to start or may shut down shortly after starting. Common causes of flame sensor failure include corrosion, dirt buildup, or a broken wire. The gas valve controls the flow of gas to the furnace. If the gas valve fails, your furnace won't be able to produce heat.
Pilot flame color changes
A yellow flame is a clear sign that the gas is not burning properly. Dirty or partially blocked systems can produce this. It's also another sign that a call to your trusted HVAC contractor is needed to save money and keep you a bit safer.
It's common for your furnace to kick on more frequently in cold weather. While it's okay if your furnace cycles on and off several times every hour, it shouldn't cycle on and off more than 8-10 times. If it does, this is known as short cycling, and it's a sign that something in your heating system needs to be fixed.
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. That means normal heating cycles last from seven to 20 minutes.
When a furnace runs constantly, it probably means that something is dirty or clogged.
All furnace manufacturers recommend annual maintenance to be performed by a qualified technician. There is also verbiage in their warranties saying that any damage done to the unit because of lack of maintenance will not be covered.
If someone is at home in the daytime, 72° F (22° C) is a good start, but aim for 68° F (20° C). If everyone is away from home in the daytime or you're asleep at night, we feel 66° F (19° C) to 62° F (17° C) is best.
The flame should stay on throughout the entire cycle, which takes 10 to 15 minutes to complete. Most furnaces run a complete cycle two or three times an hour to maintain a consistent indoor temperature.
The Average Furnace Lifespan
A well-maintained furnace can last at least 15 to 20 years, but completing annual maintenance and being diligent with repairs can extend its life even longer.
Check and Change Your Clogged Filter
This is a simple but essential part of furnace maintenance. One of the most common reasons to have a furnace not working is a clogged filter. It also happens to be the easiest maintenance chore.
Ask twenty professional HVAC contractors the question, “How Much Does A New Furnace Cost?” and you'll probably get the same answer... “It depends.” On average, the cost of a new furnace can range from $2,000 - $14,2001. However, factors like furnace efficiency, type, size, and much more can impact this range.
If your furnace is not producing heat, there are several potential causes. These include but are not limited to a broken thermostat, the thermostat being set too low, an extinguished pilot light, a blown fuse or tripped circuit breaker, a closed gas valve, or issues with the electronic ignition.
As reported by the National Fire Protection Association (NFPA), heating systems like furnaces are a leading cause of home fires, causing almost 50,000 blazes, 500 civilian deaths and more than $1 billion in significant property damage every year.
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.
For 1- to 2-inch filters, replace them every 1 to 3 months. For 3- to 4-inch filters, replace them every 6 to 9 months. For 5- to 6-inch filters, replace them every 9 to 12 months.
When the Furnace Does Not Heat the Air. The furnace not heating up is the most typical sign of a clogged exhaust vent. This occurs when the furnace inducer fan does not activate the pressure switch when it should. The inducer fan is responsible for moving air around the combustion chamber.