Why Does My Furnace Keep Running? Causes and Solutions

Why Does My Furnace Keep Running? Causes and Solutions

Are you noticing your furnace to be running longer than usual? All HVAC devices are programmed to run until the desired temperature is maintained and then turn off. Due to potential system malfunctions, your unit might stay on and consume energy for a long time, even after scheduling regular furnace services in Westminster, CO. As a resident or homeowner, you should know how to spot potential with our furnace and take appropriate measures to fix them.

Reasons Why Your Furnace Keeps Running All the Time

Below is your guide to understanding why your furnace keeps consuming energy and does not provide sufficient heating. Know the causes to find the right solution.

Wrong Thermostat Settings

The thermostat is the brain of your furnace as it controls the heating of your entire house. Therefore, uneven heating, short cycling, and lack of heat are indicators of a faulty thermostat. Often, the cause of malfunctions is old and crampy wiring, dead batteries, or a broken internal component of the thermostat.

The direct placement of the thermostat in the sun or near a heat register also confuses adjusting the temperature, as the external heat might interfere with the thermostat’s heat sensors. Furthermore, when your fan is set to ‘on’ instead of ‘auto’, it will keep the blower running without producing warm air.


You can start by replacing the batteries with new ones to see if the problem is solved. If the issue resides in the thermostat’s location, call a professional for furnace service at Westminster, CO, and ask them to relocate the thermostat to an appropriate location with moderate temperature and no direct heat.

For fan settings, you have to manually set the fan to ‘auto’ so that it reads the temperature accurately and produces warm air when needed instead of running constantly blowing cold air.

If you require a professional furnace replacement or repair services in Westminster or Thornton, CO contact 303 Heat for assistance.

Clogged Air Filters

It is the most common cause of furnaces running constantly and ultimately breakdown. These filters are the outermost components that tend to catch dust and debris, restricting airflow and causing system overheating.

It becomes difficult for the device to cool down after overheating; if ignored, it needs an emergency furnace repair service.


You should clean the filters with water every three weeks to prevent your furnace filters from clogging. If you live in a polluted region, you can try cleaning more frequently and replacing the filters every two to three months for proper uninterrupted airflow.

Pilot Light Malfunctions

A pilot light is an important indication of a proper gas supply in your furnace. The pilot light turns on when the gas reaches the burner, and the furnace starts producing heat to reach the set temperature.

When the light malfunctions, it falsely indicates the supply of gas to be sufficient. Your device runs to compensate for the decreasing temperature requiring furnace replacement in Thornton, CO, sooner than expected.

A dirty or corroded pilot light sensor will also not indicate the flame and gas, causing your system to shut down or cycle on and off frequently.


Earlier, pilot light malfunctions can be fixed by calling our professional for furnace repair in Westminster, CO. However, you can press the reset button to restart the gas supply. If the system restart does not work, call for professional help in case it might be a case of a carbon monoxide leak.

Leaky or Broken Ductwork

Blocked or broken ducts are a big reason for warm air escaping from the middle of the supply ducts. Older homes have this common problem of cracked and punctured ducts due to excessive use and mistakes during repair jobs. These small leaks can cause losses of heat, and hence your system overworks, consuming more energy.


Only a professional can perform thermal analysis to find the leaks where repair is needed. Minor furnace repair at Thornton, CO, can do well for corners and joints, but bigger punctures might need replacements.

Faulty Fan Motor

Your furnace cannot operate fully if the fan motor is broken or faulty. The furnace runs more than usual to reach that desired temperature. This continuous operation costs you more energy bills, and if left ignored for a long time, a much sooner furnace replacement in Thornton, CO, is required.


If you notice rattling or screeching sounds, turn the device off immediately and call our technician for help.


The best solution to all furnace issues is regular furnace service in Westminster, CO. 303 Heat provides you with the most affordable, reliable, and timely services in the market. Call us at 720-465-6699 for more inquiries, and schedule an appointment now.