Appliances
Gas furnaces are generally easier to operate than oil burners as natural gas and propane are cleaner burning fuels. Common issues with gas furnaces include problems with the electrical system, the thermocouple, or the pilot light.
While gas furnaces have control shutoffs to prevent gas leaks, they are not completely fail-safe. If you smell gas in your home, do not attempt to turn any lights on or off or shut off the gas leading to the furnace. Leave the house immediately, leaving the door open, and call the gas company or fire department to report a gas leak. Do not re-enter your home until it is declared safe.
 © 2006 Publications International, Ltd. Most natural gas furnaces have few operational difficulties. Problems typically involve the pilot light, the thermocouple, or some part of the electrical system. |
On some gas furnaces and heaters, the pilot light assembly is covered by a plug-type door. To access the pilot burner, simply pull the door out of the furnace housing. On other units, the panel covering the pilot and gas burners must be removed.
The pilot light controls, reset buttons, gas valves, and thermocouple are usually found in an assembly at the front of the furnace. The furnace limit switch is typically located on the plenum or main duct junction on the upper housing of the furnace.
Before you begin fixing your furnace, it’s important to identify the specific issue. Check the chart on the next page for possible problems and solutions.
For more tips on home repair, visit the following links.
- Furnace Maintenance: Learn how to keep your furnace in prime condition to save time and money.
- Major Appliance Repair: Fix other household machines in addition to your furnace with this helpful article.
- Small Appliance Repair: Once you’ve tackled the furnace, fixing small appliances like toasters and blenders will be easy.
- Thermostat Maintenance: Make sure your heating system is actually experiencing issues by checking the thermostat. Learn how to calibrate it with this guide.
secure access panels properly.
or broken.
lubrication.
if applicable.
too frequently
high.
sealing.
sealant or metal tape.
adjustment.
Make sure that access panels are securely fastened. If the belts are sticking, worn, or damaged, use belt dressing to spray the squeaking drive belts, or replace them if they are worn or damaged. If the blower belts are too loose or too tight, adjust them accordingly. If the motor and blower need lubrication and have oil ports, apply lubrication. If the burner is dirty, call a professional. The pilot light is essential for the furnace to function. Refer to the next page to learn how to light the pilot light. For more information on home repair, visit the links provided.
How to Light a Furnace Pilot Light
To check the pilot light, you will need matches and fine wire. The pilot light on a gas furnace may go out due to drafts. Follow the manufacturer’s instructions carefully to relight the pilot. If the instructions are not available, follow this general procedure:
To relight a pilot light on a gas furnace, follow these steps. First, locate the pilot light assembly which typically has a gas valve with on, off, and pilot settings. Then, turn the valve to off and wait for three minutes. After that, switch the valve to the pilot setting and hold a lighted match to the pilot opening while you push the reset button on the pilot control panel. Keep the button depressed until the pilot flame burns brightly, then set the valve to the on position. If the pilot flame won’t stay lit, the opening may be clogged. Turn the gas valve off and clean the opening with a piece of fine wire. If it still won’t stay lit after several attempts, there may be a faulty thermocouple, and you should call a professional service person. Some furnaces use an electrical system to ignite the gas, and if this system malfunctions, call a professional service person. To replace a faulty thermocouple, first, unscrew the copper lead and connection nut inside the threaded connection to the gas line. Then, insert the new thermocouple into the hole in the bracket and screw the bracket nut over the tube. Finally, tightly screw the nut into place without over-tightening it.
The thermocouple, a steel tube and copper lead, is fastened by a bracket beside the pilot light. This safety control switch, the limit switch, is located beneath the plenum on the furnace and halts the burner if the plenum becomes too hot. Additionally, it turns off the blower once the temperature drops to a specific level after the burner has shut off. If the blower runs constantly, the blower control on the thermostat may be set to the ON position or the limit control switch may need to be adjusted. Check the thermostat first, and if the blower control is already on AUTO, the limit switch will need to be adjusted.
In order to adjust the switch, the cover of the control needs to be removed. The toothed dial underneath the cover is marked LIMIT on one side, which should not be touched. The other side is marked FAN and has two pointers. The blower turns on at the upper pointer setting and off at the lower pointer setting. The upper pointer should be set to around 115 degrees Fahrenheit and the lower one at about 90 degrees Fahrenheit with the pointers set about 25 degrees apart. If gas is smelled during these repairs, it is important to address the leak immediately. There are more articles on home repair available for reference.
To ensure the safe use of a gas furnace, it is important to have a steady flow of fuel and a strong, continuous flame. These instructions will help determine that the furnace is receiving the proper amount of gas and that it is going where it should. The flames on the gas burner should be full and steady with no sputtering or yellow traces. Adjusting the height of the flame on the main burners should be done by a professional service person. The height of the pilot flame can be adjusted by turning the flame adjustment screw until the flame is 1 1/2 to 2 inches high. The adjustment screw is located near the gas valve on the pilot assembly, if the control has this adjustment feature. If gas leaks are suspected around the furnace unit, a mixture of liquid detergent and water can be used to paint the gas supply line along its connections and valves. Any point where there is a leak will cause the soapy water to bubble. If a leak is found, try tightening the leaking connection with a pipe wrench, but be careful not to overtighten. If the connections or valves continue to leak, call a professional service person. More articles on home repair are available for reference.
FAQ
1. What are the common problems with gas furnaces?
Gas furnaces may encounter several issues, such as a faulty thermostat, dirty filters, clogged burners, and a malfunctioning ignition system. These problems can cause a gas furnace to stop working or operate inefficiently. It is recommended to have a professional technician inspect and repair the furnace if these issues arise.
2. How often should I have my gas furnace serviced?
Gas furnaces should be serviced annually to ensure optimal performance and safety. Regular maintenance can prevent breakdowns, improve energy efficiency, and extend the lifespan of the furnace. It is also crucial to have a professional technician inspect the furnace before the winter season to avoid any potential issues.
3. What are the signs that my gas furnace needs repair?
Some common signs that indicate a gas furnace needs repair include strange noises, uneven heating, high energy bills, frequent cycling, and a yellow pilot light. If you notice any of these signs, it is recommended to have a professional technician inspect and repair the furnace as soon as possible.
4. Can I repair my gas furnace on my own?
It is not recommended to repair a gas furnace on your own as it can be dangerous and may cause further damage to the furnace. Gas furnaces involve complex systems and require specialized tools and knowledge to diagnose and repair the issue. It is best to leave the repair to a professional technician.
5. How long does a gas furnace last?
A gas furnace can last anywhere from 15 to 25 years with proper maintenance and care. However, if the furnace is not regularly maintained or experiences frequent breakdowns, its lifespan may be shorter. It is recommended to have a professional technician inspect the furnace regularly to ensure its longevity.
6. How much does it cost to repair a gas furnace?
The cost of repairing a gas furnace varies depending on the issue and the extent of the damage. Minor repairs such as replacing a faulty thermostat or cleaning the filters may cost less than major repairs such as replacing the furnace’s motor or blower. It is best to consult with a professional technician to receive a proper estimate of the cost of repairs.
7. Can a gas furnace be replaced instead of repaired?
If a gas furnace is too old or has experienced extensive damage, it may be more cost-effective to replace it instead of repairing it. A new gas furnace can provide better energy efficiency, improved performance, and increased safety. It is recommended to consult with a professional technician to determine whether a repair or replacement is the best option for your furnace.
Brody is a skilled craftsman and gardening expert. From renovating living spaces to cultivating lush gardens, Brody’s knowledge and passion shine through, inspiring readers to embark on their own home improvement and gardening journeys with confidence.
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