If your furnace frequently turns on and off in brief cycles, this can lead to your home being unable to reach its desired temperature. This issue is called short cycling and it occurs when both the heating and resting cycles are too short for the furnace to effectively do its job.
In this article, we will explain what furnace short cycling is, explore the main causes of the problem, and provide potential solutions.
What is Furnace Short Cycling?
The duration of a heating cycle depends on the temperature settings and the heat required to warm your home. Usually, a heating cycle lasts for several minutes and includes a subtle click from the thermostat signalling the furnace to start or stop, the sound of airflow as warm air enters your living spaces, and if close to your heating equipment, the audible ignition of burners or starting the fan motor.
Short cycling occurs when a furnace’s heating cycles are shortened, causing it to start and shut down quickly. The cycles may last for just a few seconds or a minute or two. If your furnace turns on and off repeatedly without producing heat, this could be a sign of short cycling. A properly functioning furnace cycles 3-8 times per hour but extra cycles during cold weather are normal. Short cycling strains the system and can cause significant issues and costly repairs if neglected.
Causes of short cycles and ways to eliminate them
Short cycles in a furnace can be caused by a variety of factors, and understanding them is crucial for effective troubleshooting. Let’s dive deeper into the key factors and potential solutions to your furnace problems:
Thermostat Issues:
The thermostat is vital for signalling the heating system to switch on when the temperature drops below the set point. Its malfunction can disrupt the normal cycle of the furnace. To fix it, replace the batteries, check the functionality of the thermostat and make sure it is placed in the optimal location. Avoid places such as drafty corridors or near doors, instead install it in the centre of the house for accurate temperature readings.
Improper Furnace Size for the Home:
If your furnace was installed before you moved in, it might be sized incorrectly for your home and can be the cause of frequent cycling issues. Signs of an oversized furnace include loud noises, temperature fluctuations, high energy bills, increased wear and tear, and imbalanced indoor humidity. Consult an HVAC professional to assess the unit and recommend the best solution.
Airflow Restriction:
Short cycling is often caused by restricted airflow due to clogged filters or blocked vents. To fix the issue, you can change the dirty air filter and ensure the exhaust vent is clear of blockages. Check all vents for any obstructions to ensure sufficient airflow. If the issue persists, consult an HVAC expert for a thorough inspection.
Broken or Dirty Flame Sensor:
The flame sensor is a crucial safety component in your furnace that detects the pilot light, acting as the furnace flame. If no flame is detected, the furnace automatically shuts down. Before contacting a furnace repair company, you can check the flame sensor:
- Turn off the breaker to cut power to the furnace.
- Remove the furnace’s outer panel.
- Locate the flame sensor behind the burner or near the panel opening.
- Unscrew the flame sensor using a screwdriver.
- Gently scrub the metal rod with a microfiber cloth to remove any carbon buildup.
- Once you see bare metal, use wire wool to remove the remaining buildup delicately.
- Wipe off dust from the sensor and mounting area using the microfiber cloth.
- Reassemble the unit and turn the power back on to check if the issue is resolved.
If short cycling persists, contact an HVAC expert!
Overheating:
Cold temperatures and frequent blizzards can strain your furnace blower, causing overheating and short cycling in older furnaces. This can pose a significant safety hazard, leading to carbon monoxide leaks or a fire. If you suspect overheating, turn off your furnace and call a professional for a thorough evaluation. Prompt attention is critical for maintaining your furnace’s safety and efficiency.
Is your furnace having problems or not functioning at all? Efficient air circulation is essential for maintaining home comfort and eliminating dust and allergens that can cause discomfort and health problems.
