Keeping your furnace running throughout the winter matters for your comfort and significantly impacts how much you pay for heating. While a gas furnace is generally the most effective heating option, it can also be prone to developing issues that cause it to perform poorly or suddenly fail. In this article, we’ll explore some of the most common issues you may encounter and how to determine whether repairing or replacing your furnace is the smarter choice.
Furnace Isn’t Turning On
The most obvious sign that you need to get your furnace inspected is if it fails to turn on. This is something that happens more often than you may think. There are quite a few components that all need to work correctly for a furnace to come on, for the burners to ignite, and for the blower to then start pulling in cool air and blowing out hot air.
The first thing that happens is that the draft inducer comes on and starts pulling air upward from the combustion chamber through the heat exchanger. The electronic igniter also usually comes on at the same time. The draft inducer creates negative air pressure, which activates the pressure switch. Once the pressure switch activates, the control board opens the gas valve so that gas starts flowing to the burners.
Once the igniter lights the burners, the flame sensor must quickly detect the flames. Otherwise, the gas valve will close. If even one of these components fails or malfunctions, the furnace either won’t light at all or will go out almost immediately. Luckily, all of these components, other than the draft inducer, are relatively easy to repair.
Furnace Is Running but Not Putting Out Any Air
Another thing that can sometimes happen is that the furnace will light, but the blower won’t come on and start circulating air. This typically leads to the furnace shutting off fairly soon since it will eventually overheat if cool air isn’t flowing over its heat exchanger. This issue usually indicates that the blower motor is worn out, has an electrical issue, or that there’s a problem with the control board, and it isn’t telling the blower to come on.
Another possibility is that the temperature limit switch is faulty, as this component signals the blower to turn on and off. Replacing either the control board or the limit switch is relatively inexpensive compared to some other furnace repairs, but replacing the blower, which can cost anywhere from a few hundred to the cost of buying a new furnace, makes more sense than repairing it.
Cold Air Blowing Out of Your Vents
It’s actually fairly rare for a furnace system to put out cold air since the blower typically won’t run if the furnace is off. The only exception is if you accidentally have the fan setting on your thermostat switched to On instead of Auto, as this results in the blower always running. If you do notice cold air coming from your vents, it usually means that the blower didn’t shut off when it should have due to an issue with the control board, thermostat, or temperature limit switch.
The other possibility is that your furnace recently overheated and shut down. In this case, the blower will continue to run for some time so that it keeps pulling cool air through the furnace to help the heat exchanger cool down more quickly. If you suspect your furnace has overheated, you should immediately change the air filter since overheating most commonly happens due to a dirty filter. If this doesn’t fix the problem and your furnace keeps blowing cold air, you’ll need a technician to troubleshoot the issue.
Long Heating Cycles
Even in the Chicago area, where it can get freezing cold during the winter, a well-functioning furnace should rarely run for over 15 to 20 minutes once the house is fully heated. When you turn the temperature back up in the morning or after work, the initial heating cycle will be quite a bit longer, but each cycle after that should be fairly short and take about the same amount of time. If your average heating cycles are much longer, it indicates your furnace isn’t heating effectively for one reason or another. One possibility is that the furnace is giving out, but it could also be that you need to have it maintained or repaired.
Furnaces can stop heating effectively for a variety of reasons, such as ductwork issues, dirty burners, or a malfunctioning or worn-out blower. Your furnace will also eventually start performing poorly if you wait too long to replace the air filter.
Loud or Unusual Noises
Although furnaces can be somewhat noisy, a sudden increase in noise or any unusual sounds is another sign your furnace isn’t working properly. For instance, squealing or screeching noises usually mean the bearings in the blower motor are wearing out. You want this fixed quickly. Otherwise, the blower motor will likely end up burning out. A rattling sound is also something you definitely shouldn’t ignore.
While it can sometimes be caused by a loose component, it can also indicate that the furnace’s heat exchanger is cracked. This is the worst problem a furnace can experience, as it can allow carbon monoxide to leak into the ductwork and be blown into every room. It’s also an issue that will usually require you to replace your furnace, as you might end up paying almost as much to replace the heat exchanger as you would to install a new furnace.
Water Leaking Out of Your Furnace
If you have a high-efficiency condensing furnace, there’s a chance it could start leaking water. Condensing furnaces capture so much heat from the combustion fumes they produce that the water vapor in the fumes condenses. All of the water then gets channeled away from the furnace through its condensate drain system. If water is leaking out, it means that a drain line is clogged or broken, or that there’s a hole in the drain pan that collects the water.
How To Decide Between Repairing or Replacing Your Furnace
It can sometimes be difficult to determine whether it’s worth repairing your furnace when it stops working properly. When facing a furnace repair, the main thing you want to consider is how many more years of life your furnace has left. The average lifespan of a gas furnace is around 15 to 20 years. That means if your furnace is already 12 to 15 years old and needs a fairly major repair, you’re usually better off installing a replacement. Even if your furnace is only eight or so years old, replacing it may still be the best option if it’s going to cost over $1,000 to repair it.
Since 1946, IBBOTSON Heating & Air Conditioning Co. has been the go-to heating and air conditioning source in Arlington Heights. We can repair, install, and maintain all types, makes, and models of furnaces, ACs, and mini-splits. When you need furnace service, give IBBOTSON Heating & Air Conditioning Co. a call, and we’ll get everything taken care of as soon as possible.
