During the winter months, you want to ensure your furnace is in great working condition. Even one day without proper heating can significantly impact your comfort. While there are a lot of things you can do to keep your furnace working properly, you may still deal with problems. One problem you may experience as your furnace breaks down is furnace short cycling.
This common problem can lead to your system cycling between on and off more rapidly and frequently than it normally does, leading to struggles to maintain your indoor temperature. But understanding the cause of furnace short cycling isn’t so simple. In this blog, we’ll help you identify a few common causes to help you determine when it’s time to call for support.
What is Short Cycling?
When your furnace is in good working condition, it runs in cycles. These cycles go for 10 to 20 minutes, and can occur two to three times per hour to maintain your desired temperature. However, as temperatures drop, it isn’t uncommon for you to also experience 100% runtime to maintain your desired temperature.
On average, these longer, gentler heating cycles are better for your home’s energy efficiency than if the system is rapidly turning on and off. However, you may begin to notice that your system is turning on and off every few minutes, also known as furnace short cycling. This often signifies a major problem within your system and can compromise your system efficiency.
Common Causes of Furnace Short Cycling
Understanding the cause of your furnace short cycling is the first step in seeking appropriate care for the system. However, identifying the cause isn’t always easy, and it is often best to reach out to a trusted HVAC professional for support. If you’re experiencing furnace short cycling, this may be caused by one of the following:
1. Dirty Air Filters
One common cause of furnace short cycling is dirty air filters. On average, your air filters should be replaced once every one to three months. When this task goes overlooked, it can block airflow, leading to backups. Instead of releasing the warm air into your home, it may become trapped in your furnace. As temperatures rise in the system, your furnace will shut off, before turning back on due to inadequate temperatures in your home, leading to the short cycling. If you want to avoid this, replace your filter regularly to avoid blockages.
2. Overheating System
When the temperature monitoring systems within your furnace begin to malfunction, it may struggle to keep itself cool and shut down while it attempts to reach a safer internal temperature. If it is frequently overheating, these shutdowns may be the cause of your furnace short cycling. Additionally, a malfunctioning heat exchanger may also be the cause of short cycling. Whether it is caused by your temperature monitoring system or heat exchanger, it is in your best interest to reach out to an HVAC technician for professional support, as DIY repairs may do more harm than good.
3. Improper System Size
While a larger furnace might seem like a good investment, it can lead to problems in your home. An improperly sized system is a common cause of furnace short cycling. An improperly sized furnace is a frequent cause of short cycling. If a furnace is too large for your home, it will rapidly reach the thermostat’s set temperature. Because the system heats the home too quickly, the thermostat signals the furnace to shut off almost immediately. This frequent, rapid cycling places excessive strain on components and significantly reduces energy efficiency.
4. Thermostat Problems
Another common cause of furnace short cycling is a faulty thermostat. To determine if this is the cause, start by assessing the device. Double-check that it is set to the proper temperature and the heat setting, and that it has adequate access to a power source. If it is properly set and isn’t experiencing any power problems, it is best to reach out to your HVAC team for repairs. They can perform a more thorough examination of the device and make any necessary electrical adjustments to help you stop this short cycling.
5. Damaged Electronics
Modern furnaces rely on complex electronic components, including control boards and wiring, to manage and regulate their operations. Damage to these electronics, often caused by power surges, general wear, or water exposure, can lead to inconsistent signaling. A faulty control board might improperly instruct the system to shut down prematurely, despite the home not yet reaching the set temperature. This interruption in the intended heating sequence causes the furnace to repeatedly turn on and off in rapid succession, resulting in short cycling and requiring professional repair.
6. Flame Sensor Issues
The flame sensor is a critical safety component designed to detect the presence of a flame when the burner is active. If the sensor is dirty, damaged, or malfunctioning, it may incorrectly signal to the control board that no flame is present, even when the furnace has successfully ignited. This immediate loss of signal triggers the safety mechanism, causing the furnace to shut down prematurely. Since the thermostat still calls for heat, the furnace attempts to restart almost immediately, only to shut off again when the faulty sensor fails to prove the flame. This cycle of rapid ignition and shutdown is a classic form of short cycling.
Call Us If You’re Dealing with Furnace Short Cycling
When you notice the earliest signs of furnace short cycling, it’s essential that you reach out to your trusted HVAC team for support. If you’re looking for expert support in the Roy, UT, area, turn to our team at R&D Heating & Air for support. With decades of experience, you can trust that our team will quickly diagnose the problem and have the tools and training to make essential repairs. Don’t spend another winter day fighting with your furnace when help is only a phone call away.
If you need help addressing furnace short cycling, don’t hesitate to contact us to schedule an appointment.
