Furnaces always run in heating cycles. Each cycle is when the furnace turns on, the thermostat registers the proper temperature, and the furnace switches off.
According to furnace service professionals, if your furnace is well-maintained and functioning correctly, it will typically complete two to three heating cycles each hour, each lasting around 10 to 15 minutes.
That being said, a few variables can influence the length of each cycle or the number of cycles the furnace performs per hour.
Outdoor temperature is undoubtedly one of the most important aspects because it influences how quickly your home cools down and how much heat is required to restore the temperature.
In below-zero temperatures, where much more heat is required, it is not uncommon for each heating cycle to run up to 20 or 30 minutes, with the furnace only turning off for five to 10 minutes before beginning the next cycle.
Another aspect is the discrepancy between the thermostat setting and the inside temperature when the furnace is turned on. If the indoor temperature is more than 2 or 3 degrees below the thermostat setting, the initial heating cycle will last longer since more heat is required to bring the temperature back up.
Understanding short-cycling and long cycling
Short cycling occurs when the furnace barely runs for a few minutes before shutting down, sometimes before the thermostat registers the proper temperature. This problem is usually caused by the furnace being much bigger than is required to heat the house adequately.
Short cycling can also occur when the furnace overheats due to insufficient airflow or other causes.
If your furnace runs continuously for more than 20 minutes, even in milder conditions, it suggests a problem keeping it from heating correctly and effectively. The only proper solution to troubles with short or long cycling is to inspect your furnace professionally, as this is the only way to know what is causing the problem.
If you are inexperienced, don’t try to fix the unit, as you will likely cause more problems than are there.
Reasons for your furnace cycling on and off
If you find that your furnace is cycling more frequently than expected, this could be because:
The furnace is the wrong size.
A larger furnace does not always perform better. Furnace short cycling is frequently the direct outcome of an extremely large system. But wouldn’t a larger furnace heat a home more quickly and efficiently? Surprisingly, the answer is NO.
While a big furnace might swiftly heat a smaller home, it does not uniformly distribute the air. The system will shorten the cycle to maintain consistent temperatures throughout the house.
What size is best? Energy.gov suggests 12,000 BTUs per 400-500 square feet, although this figure may vary depending on your home’s insulation and local temperature.
The furnace is overheating.
When it’s cold outside, your furnace may be flaring up inside. Overheating is a major cause of furnace short-cycling. What causes overheating? In many cases, restricted airflow is the cause. A blockage in the ducts or a clogged filter can prevent air from leaving the system.
The furnace is past its prime.
How old is your furnace? As the system ages, you may notice the furnace turning on and off more frequently. Furnaces survive an average of 15 to 20 years. As it nears the end of its life, it may not run as efficiently as previously. Short cycling indicates that upgrading to a newer model is time.
A malfunctioning thermostat.
The thermostat informs the furnace when to cycle. If the thermostat fails or malfunctions, your furnace cannot shut down. Where you position the thermostat also matters. To prevent your furnace from cycling too frequently, ensure the thermostat is not too close to a heat source or in direct sunlight.
A dirty flame sensor.
Does your furnace cycle for only a few seconds at a time? A filthy flame sensor could be the cause. Cleaning the sensor will assist in regulating cycles and prevent dangerous gas leaks in your home.
Is it too cold, or is your furnace short-cycling?
Extremely cold temperatures can cause your furnace to turn on more frequently. It will do everything it can to keep up with outside temperatures, even if it means cycling more regularly.
While this is the case, your system should not turn on and off every few minutes simply because there is a covering of snow on the ground. Furnace cycles should continue until the home reaches the desired temperature.
You must consider several aspects when assessing whether or not consistent cycles are caused by severely cold weather. How well-insulated is your home? Losing too much heat through the roof, windows, or entrances will make your furnace run more frequently. High ceilings and single-pane windows are common culprits.
If your furnace only turns on for a few minutes and your home never warms up, it’s most likely due to short cycling. Colder temperatures will cause the system to work harder, but if the cycles continue to shorten, it is necessary to have the furnace evaluated by an experienced professional.
How do you keep your furnace working optimally?
To be comfortable in your house, you must ensure that the furnace is running optimally at all times. And the good news is that it’s possible.
For one, you must ensure all unit parts are running properly. This calls for you to inspect the unit at least once before heating the house. If you notice any issue with the unit, you should stop using it until you have fixed it.
Don’t hire just any furnace repair service Port Jefferson provider. Take your time to research and find an experienced professional who knows what they are doing. The last thing you want is someone who causes more problems than were originally there.
If a contractor recommends that you replace a unit such as a thermostat, replace it immediately before other parts begin falling apart.