Home DIY: Troubleshooting Tips for Conventional Gas Furnaces

If you have a gas furnace powering your forced air heating system, you are among the majority of homeowners in the United States. Gas furnaces are both efficient and relatively simple. These combined qualities make them highly reliable, but that doesn’t mean things can’t go wrong every now and then. Read on to find out which furnace issues you can tackle yourself and which you should leave to the professionals.


Know Your Furnace


Before you pick up the phone to call for help and before you start repairing your furnace yourself, you need to know what type of gas furnace you have. The dividing line is based on efficiency. Older furnaces, called conventional gas furnaces, have AFUE (annual fuel utilization efficiency) values of 89% or less. Newer furnaces, called high efficiency condensing furnaces, have AFUE values of 90% or more. High efficiency furnaces are substantially more complex.


Beyond knowing the type of furnace you have, you should be familiar with its parts. Most forced air systems are made up of a cold air return to bring cold air into the furnace, the furnace itself, and then the ductwork that carries hot air to the house. Between the cold air return ducts and the furnace will be a filter. The inside of the furnace contains a gas burner as well as a fan to circulate the air. In some cases there is a humidifier mounted to the furnace or the cold air return.


In many cases, the problem with a furnace is simple and does not require the intervention of a professional. You can search online, at sites like InterstateAir.com, to learn more about when it is best to call a professional and to get advice on DIY items. The following is a look at common problems and their DIY solutions.


The Thermostat


If the thermostat is set too low or isn’t working, then the furnace won’t get the message to power on. In the case of a low setting, just turn up the heat. If the thermostat itself isn’t working, you can clean it or replace it. If you have a conventional thermostat. Simple, programmable thermostats sell for less than $40 at most home improvement centers and can be installed in less than 15 minutes.


The Electrical Connection



The fan on a furnace requires electricity to run. If the system overloaded for some reason, then a circuit may be tripped or a fuse may be blown. Check your electrical panel to see if you can flip the breaker or replace the fuse. If a circuit keeps tripping or a fuse keeps blowing, something is wrong and you need to get the help of a professional.


The Pilot Light


Another reason a furnace won’t create heat has to do with igniting the fuel. Your furnace will have either a standing pilot or an electronic ignition. In the first case, you may have noticed a small blue flame burning inside the furnace at all times. It serves as the ignition source for a larger flame when heat is required. If this pilot goes out, you won’t have any heat, but you can relight the pilot by following the instructions in the furnace’s manual. Most furnaces will have a red reset but or knob that you can use to turn the pilot on and off. You simply turn on fuel supply to the the pilot and light it with a match. Be sure to check for any fuel leaks before lighting the pilot.


If you have an electronic ignition, then you will probably need professional assistance to get it working. Check your manual to determine what you need to do to attempt to reset the unit yourself. If that doesn’t work, call a professional. They can often guide you through reset procedures over the phone and will send someone to repair the system if it can’t be reset.


The Filter


You will need to change the filter in your furnace every 90 days or so. If you don’t, your furnace to produce less heat than normal. If changing the filter doesn’t fix the problem of too little heat, then you will need to call a service technician to adjust your burners and evaluate the overall function of the system.


A dirty air filter may also cause your system to cycle on and off frequently. If you feel the system comes on and off too many times in an hour, check the filter. If it isn’t dirty, check the thermostat to see if it has any settings that control how often a furnace turns on and off. If neither of those things work, your blower motor may be malfunctioning. You can check for a loose belt, but in general you should just call a professional.


Getting Help


There are a number of things that can go wrong with a furnace and the tips above only cover a few. If you need help, call a professional. They can often provide troubleshooting advice over the phone and will be able to help you pinpoint problems in your specific make and model of furnace. It is a good idea to have routine maintenance performed on your furnace each year. This not only helps reduce problems, it also ensures that the service company knows you and your furnace and that you know them. Then, when you do call with a problem, you can get customized advice from someone you know and trust.


John Young enjoys refurbishing houses. He often blogs about home construction projects to help the everyday person make smart homeowner decisions.


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