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Why You Have a Furnace That Shuts Off Too Soon

Any homeowner in New Jersey needs to have a powerful heating system to get through the winters. In most cases, that heating system is a gas furnace, which is the most common type of residential heater found in homes across the country. Gas furnaces are energy efficient, powerful, and reliable. Of course, no heating system can be 100% reliable, and in this post we’re going to look at one furnace issue you may have—a furnace that keeps shutting down early before it can evenly warm your house.

The Furnace Cycle

A quick run-through on how your furnace goes through a full heating cycle: The thermostat registers the house has gotten too cold and sends a signal to the furnace control board to initiate heating. Gas begins to flow to the burners and the electronic ignition system lights them. The hot gas from the burners moves into the heat exchanger, and when a device called the limit switch detects the heat exchanger is hot enough, it activates the blower. 

The blower draws air through the return air vent and sends it around the heat exchanger, where it picks up heat. The air continues into the ventilation system and the rooms. When the thermostat signals the house is warm enough, the gas flow shuts off. Once the limit switch detects the heat exchanger has cooled down, it turns off the blower, ending the heating cycle.

How the Furnace’s Heating Cycle Can Get Cut Short

Now that you know the full process of the heating cycle in your gas furnace, it will be easier for you to follow along with the various ways it can malfunction, leading to the cycle ending early (a.k.a. short-cycling).

  • Faulty thermostat: The thermostat may incorrectly signal to the furnace to cut short the heating cycle before it has reached the desired indoor temperature. This often occurs because the thermostat is miscalibrated and reads the house as hotter than it actually is.
  • Clogged air filter: The blower pulls air from the return air vent through a filter to prevent dust contamination inside the furnace. The filter will become clogged after one to three months, and this will restrict airflow. Without enough airflow, the heat exchanger won’t cool down and the limit switch will shut the furnace off as a safety measure. 
  • Broken flame sensor: This sensor makes sure that the gas from the burners has ignited, preventing unburned gas from building up in the combustion chamber. If the sensor is broken, it may turn off the gas accidentally and stop the heating cycle.
  • Age: If the furnace is more than 15 years old, the problem may be that the system is too worn down to operate properly. 

Fixing the Problem

If the furnace has a clogged air filter, you can resolve the problem on your own. Just put in a clean air filter. (Make sure to keep up with regular changes to avoid more trouble in the future.) For other situations, you’ll want to call our professionals for furnace repair in Bergen County, NJ, or possibly even a furnace replacement.

DB Heating & Cooling, Inc serves the heating and cooling needs of customers throughout Rockland County, NY as well as Bergen County, NJ and surrounding communities. You can count on us for expert services. Contact us today!

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