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Reasons Your Furnace Keeps Kicking On and Off

Reasons Your Furnace Keeps Kicking On and Off

February 6th, 2023


One of the most common troubles that homeowners run into with their heating during the winter is a furnace that keeps turning on and off rapidly, going through what’s known as “short-cycling.” 

The standard heating cycle for a furnace is at least 15 minutes and often not much longer than 20. This is the amount of time necessary for the furnace’s components to work together to heat air, send it through the ventilation system, and raise the home’s temperature to the target on the thermostat. 

When a furnace starts to cut short its heating cycle and then restarts a short time later, it creates a problem that affects home comfort, energy consumption, and the amount of wear and tear on the furnace. If you’ve got this problem with your furnace, you’ll want it corrected as soon as possible. We’ll look at why this may happen and what you can do about it.

Airflow Troubles

When a furnace has low airflow, it allows the furnace to overheat because there’s not enough air moving through it to cool off the heat exchanger. The most common cause of low airflow is, thankfully, an easy one for you to correct on your own: a clogged filter. The furnace’s air filter will become clogged with dust, lint, and other debris after 1–3 months and choke off airflow. Put in a clean filter and this should solve the problem.

Another easily fixed airflow problem is blocked vents in the house. When vents are obstructed, it causes air pressure and airflow in the ventilation system to decline. Check to see all vents are clear, with no furniture, rugs, or other objects blocking them.

An airflow problem you can’t repair yourself is when the blower fan is faulty or has accumulated too much dirt. You need technicians to help with this.

Thermostat Issues

A malfunctioning thermostat can cause the furnace to continue to shut down early. If the thermostat has a temperature reading miscalibration, it will turn the furnace off before it can reach the temperature setting. The thermostat might also have frayed or otherwise damaged wiring, or it may be so old and out of date that it can’t do its job anymore. Repair professionals can find the best way to solve thermostat problems.

Malfunctioning safety mechanisms

The safety mechanisms in a furnace can end up doing their job too well. The flame sensor in the furnace detects that the burners have ignited, and if this part malfunctions, it will shut off the gas to the burners even if they’re working as normal. The furnace limit switch that measures the heat of the interior of the furnace may also be responsible for shutting the furnace off too early if it’s detecting incorrect temperatures. Always leave safety mechanism repairs to experts.

The best way to prevent furnace problems is to always schedule heating maintenance in Alpharetta, GA before winter—but it’s still not too late to have it done. If you’ve got a short-cycling furnace and troubleshooting won’t solve the trouble, call us for expert repairs.

Dayco Systems has been Metro Atlanta’s choice for more than three generations. Contact us when you need help with your home heating.