Troubleshooting Your Furnace When it Stops Working

Troubleshooting Your Furnace When it Stops Working
Your furnace keeps your home warm and cozy, so it's essential to maintain it. A furnace can stop working for various reasons. A lack of gas supply or a tripped breaker can prevent the furnace from receiving the energy it needs to operate. Leaking ducts or a clogged air vent might keep your system from running smoothly, and a malfunctioning thermostat can interfere with the warm air the system distributes. If your furnace stops working, some troubleshooting tips can help you identify and repair the issue. Continue reading to learn more about troubleshooting your furnace and maintenance that can keep the unit running.

How Do Furnaces Work?

Furnaces burn fuel to warm air and evenly distribute it throughout a building. They can operate on electricity, oil, coal, wood or gas, but gas-burning furnaces are the most common. Furnaces contain the following parts:
  • Thermostat
  • Gas valve
  • Ignitor and flame detector
  • Combustion air intake
  • Burners
  • Transformer
  • Blower fan
  • Air filter
  • Supply-air plenum
  • Return-air plenum
  • Heat exchanger
  • Exhaust pipe
A home's gas supply is outside, and a pipe connects the storage tank or local gas supply network to the furnace inside. When gas enters a furnace, a burner lights it, allowing the fuel to warm incoming cold air in the heat exchanger. The furnace's gas valve regulates the incoming gas pressure, and the combustion pipe's exhaust exits the home via a vent and an exhaust pipe. Thermostats detect when different rooms need more heat, and a blower fan directs heated air throughout the home. As the plenums send warm air to the ducts and the blower fan distributes heat, a room's internal temperature increases, and return ducts redirect cold air to the furnace. A furnace also contains a heat exchanger, which separates the combustion process from the air the blower fan emits. Cold air blows over the exchanger, which warms it before it reenters the home. When a thermostat senses that a room has reached its set temperature, it prevents warm airflow by switching off the furnace's gas valve.

What Would Cause a Furnace Not to Kick On?

Furnaces are typically reliable heat sources, but yours could fail to operate for various reasons. Whether your furnace stopped working overnight or you start to feel cold air coming from specific areas in your home, understanding how to troubleshoot furnace issues can help you keep your home warm and comfortable. A furnace can stop working for the following reasons:
  • Clogged air filter
  • Lack of gas supply
  • Extinguished pilot light
  • Closed or blocked vents
  • Leaking ducts
  • Faulty power source
  • Malfunctioning thermostat
  • Incorrect thermostat readings
  • Damaged or broken parts

Check the Air Filter

The air filter is the first furnace component you should check if your system stops working. Furnace filters collect dust and dirt over time, clogging filters and causing complications. A clogged filter can hinder airflow and decrease indoor air quality. In some situations, a clogged filter stops a furnace from operating. Excessive dirt and dust in the filter can also cause premature breakdowns or fires, so cleaning and replacing them as needed is essential. You should check your furnace filter once a month or every 30 days with the following steps.
  • Turn your thermostat and furnace switch off: You should always power your entire system down before working on it.
  • Hold your filter up to a light source: Holding your filter up to the light is a quick way to check for clogs. If the light does not shine through, you should clean or replace the filter.
  • Install a new filter: To install a new filter, make sure its arrows point in the airflow direction.
  • Return the access panel: After replacing or cleaning your filter, secure the access panel over it.

Check the Gas Supply and Pilot Light

Your furnace can also stop working if the pilot light goes out or it loses its gas supply. Check the gas valve outside your home to ensure the switch is parallel to the gas line. You can also check your gas supply by turning on other gas appliances in your home. If those still work, this indicates that the furnace is to blame. If not, ensure your gas supply has the correct connections or call your utility company for assistance. If your furnace flame is out, turn off your gas supply and relight the pilot. It's crucial to check your furnace's owner's manual before relighting the pilot so you follow the proper steps. Before relighting the pilot, turn the gas supply off and wait 10 to 15 minutes. Smell the air to check if any gas odor lingers. If you still smell gas, evacuate your home immediately, move a safe distance away from your home, call the fire department and contact your gas company. A lingering gas odor may indicate a leak, which is dangerous and can lead to an explosion. If there is no gas odor 10 to 15 minutes after turning off your gas supply, you can follow your owner's manual's directions to carefully light the pilot.

Check the Vents and Ducts

If hot air comes out of your air vents but you still feel cold spots, your furnace's air ducts could need some attention. Air ducts contain protruding handles known as dampers, which control the system's airflow. The dampers should be fully open for proper airflow, so you may need to open them if you notice cold spots in your home. Move any furniture, drapes, wall art or plants that may be blocking your vents to achieve maximum airflow. If you notice an entire room or multiple rooms are cold, the system's ducts may be leaking, blocked or improperly designed, which can hinder airflow. You can locate leaking or blocked ducts by inspecting your system's accessible ducts. Check for gaps between sections and points that branch out, and seal any open gaps with metal duct tape. You should also contact a professional to clean and repair your ducts. Leaking or blocked ducts are severe complications and can significantly increase your energy bills, so it's essential to address this complication as soon as you notice it.

Check the Electrical Panel

Your furnace's power source can also cause it to stop working. Before checking your furnace's power source, make sure your feet and hands are fully dry. To prevent injury, contact a qualified electrician if you notice any signs of moisture or electrical damage in your system. Check the furnace switch near the furnace to make sure it's on. If someone bumped it and accidentally turned it off, you only need to turn it back on. If you flip the switch and the furnace still doesn't work, you may need to check the electrical panel. Check the fuse or breaker box to ensure the power is on. Next, do the same for your HVAC breaker. If your electrical panel has labels, you can use them to find your breaker. If your panel lacks labels, you can find the HVAC breaker by looking for the switch that points in the opposite direction of the rest. Switch it back in the same direction as the others to turn it on. You may also need to reset your breaker. Flip the HVAC switch completely off and then back on again. If you hear a click, you have successfully reset the breaker. In some situations, you may need to re-power a fuse box. To restore power, examine the fuse box for a discolored and melted fuse. Unscrew this fuse and replace it with an identical one. You can take your melted fuse to the store to help you find a replacement. After restoring power, turn the furnace switch on to check if the system works. Contact a professional if the breaker continues to shut down or the furnace's power is still out.

Check Your Thermostat

Troubleshooting some potential thermostat complications can also return your furnace to working condition if your thermostat is malfunctioning or programmed incorrectly. First, ensure your thermostat is on the “heat” setting, and adjust the temperature to five degrees warmer than the room's current temperature. Replace the thermostat's batteries if necessary, and dust the thermostat if you have an electromechanical thermostat. You can use an object such as a soft paintbrush to lightly brush away dust and dirt. It's also important to check your thermostat's location. If your furnace is not turning on with the thermostat, it may be reading too much heat. Heat sources such as space heaters, lamps, sunlight and ovens can cause thermostats to receive false readings. Make sure your thermostat is receiving the correct input so it can send out the correct output.

Turn the Furnace off and on Again

Sometimes, a simple reset can fix your furnace. Try turning your furnace off and back on again to see if this restores your heat. Each furnace is different, so follow your owner's manual to properly reset the system.

Call for a Professional

Some furnace issues require professional maintenance. If your system has a damaged or broken part, diagnosing it can be challenging unless you know what you're looking for. A professional can identify issues and promptly repair them. Always have a backup heat source available in case your furnace needs maintenance. An alternative heat source and plenty of blankets can help you and your family stay warm if you ever need to schedule maintenance and wait for repairs.

What Does It Mean When a Gas Furnace Turns on but There's No Heat?

If you notice your furnace is running but your home lacks heat, there is most likely an issue with the system's ignitor. A furnace can operate when it has adequate energy. However, without an ignition, the blower motor will run without distributing warm air. The furnace needs an ignition to heat the air it distributes, and the ignitor is the part responsible for creating the necessary spark. A furnace will distribute cold air if the ignitor fails to create a spark. If you notice cold air circulating throughout your home, check the thermostat and gas valve to ensure they are working properly. You may need to relight the pilot light to restore a heat source to the furnace's distributed air. If these troubleshooting tips do not do the trick, contact a professional technician for assistance.

How Should I Maintain My Furnace and Keep My Home Safe?

Maintaining your furnace and following safety guidelines prevents damage and injury. It can also help you extend your furnace's life span. To care for your furnace and keep your home safe, consider the following tips:
  • Keep the surrounding area free of flammable items.
  • Remember to change the air filter regularly.
  • Schedule annual maintenance by a professional technician to make sure your system is running smoothly.
  • Keep at least two-thirds of your home's heat vents open to prevent excessive heat from building up in the furnace.
  • Keep your home's heat vents clean, and avoid obstructing them with furniture or objects.
  • Install at least one carbon monoxide detector in your home and test it monthly.
  • Check or replace your CO detector's batteries at least twice a year.
Keeping flammable items away from your furnace is crucial. Since a furnace operates on gas, nearby flammable items can pose a potential fire hazard. Regularly changing your air filter can prevent your system from clogging, and scheduling routine maintenance allows a technician to identify potential issues before they cause damage. You should always keep at least two-thirds of your vents open so heat can disperse throughout your home instead of accumulating inside the furnace. It's also essential to keep the vents clear of obstructions and free of dust and dirt. Your furnace disperses exhaust outside your home to keep the indoor air clear of carbon monoxide. However, you should still have one or more CO detectors in your home to alert you if there is a leak. Carbon monoxide poisoning can cause severe health complications and death, so evacuate your house immediately and call 911 if your detector sounds.

Invest in a New Furnace With Ingram's Water & Air

A furnace ensures everyone in your household stays warm all winter, so it's crucial to keep yours running efficiently. If your furnace fails to operate or distributes cold air, some simple troubleshooting can help you resolve any issues and restore heat throughout your home. Always remember to follow safety precautions, and contact a professional technician if you are ever in doubt about what your furnace needs. You may need to replace your furnace to maintain an ideal temperature for you and your family. Investing in a new furnace is an excellent way to ensure your home remains warm during the cold season. Ingram's Water & Air offers a wide range of high-quality furnaces to keep your home comfortable and save you money. Browse our selection of furnaces to upgrade your heating system.
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Wow that was unusual. I just wrote an incredibly long comment but after I clicked submit my comment didn't show up. Grrrr... well I'm noot writing all that over again. Anyways, just wanted to say wonrerful blog!
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