6 Common Furnace Problems

Is your gas furnace giving you trouble? The majority of furnace problems are caused by just 6 problem areas.

Simple Furnace Problems You Can Fix Yourself

Some furnace problems you can easily fix without needing to call us. Try checking for these problems yourself first, then if they are not the cause of your furnace problems, you’ll need to schedule a service call.

Clogged air filter

Clogged air filters are one of the biggest causes of furnace problems (and A/C problems too!). If your furnace turns on but doesn’t blow hot air very long, there is a good chance that your filter is too clogged. When dust builds up on the filter it reduces airflow through the system and this can cause your furnace to shut off. So check for dirty air filters. If you have questions about what filters to use, read our guide to air filters. If you find this is your problem, it could have caused soot to collect in your heat exchanger, so you should consider scheduling a non-emergency furnace cleaning and safety check.

Thermostat Problems

thermostat problems

Sometimes the furnace doesn’t work because the thermostat isn’t set correctly. This is more common with programmable thermostats because you might have set up a program last spring and forgotten about it when you try to turn your heat back on in the fall. So verify the temperature setting and that the thermostat is set to heat, rather than “air” or “off.”

Circuit Breaker Tripped

Occasionally, something has caused the circuit breaker to the furnace to trip, turning it off. Also, there is usually a switch (looks just like a light switch) near the furnace that turns it on and off. Verify that nobody turned this off by mistake, while trying to turn off the attic light, etc.

Furnace Problems You’ll Probably Need Help Fixing

Ignition Problem

Modern gas furnaces no longer use standing pilot lights. Instead they use either intermittent pilot or hot surface ignition to start the furnace. These are more efficient than a standing pilot light because they are not constantly burning a small amount of gas just to keep the furnace ready to start. Most common is the hot surface ignition system, which is sort of like the filament in an Edison light bulb. When the thermostat signals the furnace to switch on, electricity runs through the igniter and heats it up. Just like a standard light bulb, the igniter is a thin piece of metal and will not last forever.

Other problems can occur with ignition in modern gas furnaces. Safety switches can break, computer boards can fail, or other malfunctioning parts of the furnace can keep the ignition system from working. If the furnace isn’t kicking on and you’ve checked the thermostat, there is a good chance the problem is somewhere in the ignition system. Figuring out exactly where and how to fix it is something our trained heating repair technicians are very good at.

If you have an older furnace, you might still have a standing pilot light. Sometimes the pilot light has gone out for some reason and you can just light it again. If you have a furnace with a pilot light, it isn’t nearly as efficient as a modern furnace and you should be able to save quite a lot on your heating bills by replacing it with a new one.

Furnace Burner working properly

 Burner Needs Adjustment or Cleaning

Once the furnace is lit, it relies on a burner to heat the air that is then blown through your air ducts and delivered to the rooms in your home. Sometimes the ignition system will work fine, but the burner won’t lite. Other times, the burner won’t work properly. This could also lead to no heat, or very poor efficiently (meaning you’ll have really high bills). Figuring out that the burner is dirty or needs adjustment requires looking inside the furnace, which isn’t something most people are qualified to do. There are safety concerns when making adjustments and repairs to gas appliances, as you do not want to accidentally cause a gas leak or carbon monoxide in your home. A maintenance plan is one way to prevent problems from poorly adjusted or dirty burners, because we’ll be there to service them each fall. Once there is a problem, however, it is best to give us or your local licensed HVAC contractor a call to have them repair your furnace.

Belt Problems and Blower Problems

The most common blower problems are probably belt problems, but sometimes a more serious problem creates similar symptoms. If your furnace is making a high pitched sound, it is likely the blower belt or the blower itself. The best way to resolve this problem is to have a qualified heating repair technician inspect and diagnose your system. Sometimes fixing this problem can be as simple as lubricating it. The belt could also be worn. Both of these situations can usually be avoided with annual maintenance inspections. Sometimes, the problem is with the blower motor or another mechanical part which will either need repair or replacement.