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10 Common Furnace Problems & How to Fix Them

Technician repairing residential furnace.

St. Louis and Fenton area homeowners know – you don’t want to go through a Missouri winter without heat. And if your furnace isn’t working properly, that’s exactly the risk you face. Luckily, many common furnace problems can be solved with a little effort. Let’s take a look at 10 common furnace problems and our do-it-yourself tips to fix them.

If you are already experiencing a furnace problem that requires professional attention, call the trusted team at Metro Heating & Cooling at (314) 845-5900 for full furnace repair service.

Problem #1: Thermostat Turned Off

Much like you make sure an appliance is properly plugged in when it’s not working, your first step should be to check the thermostat is on. It’s often the culprit behind many service calls! Here are some common thermostat issues you can easily fix yourself: replacing batteries, cleaning dust or debris that may be clogging it, checking the breaker, and ensuring the thermostat is programmed to the correct settings (“heat” and at least five degrees above room temperature).

Problem #2: Clogged Filter

Changing your furnace filter is an easy yet often overlooked maintenance task. Staying on top of it protects HVAC components and improves air quality and flow. When the filter is clogged, the air handler works harder to make up for the lack of airflow. Not only does this drive up your utility bill, it can cause your heat exchanger to overheat and shut off prematurely. Check your air filter and replace as necessary, making sure it is installed correctly.

Problem #3: Dirty Burner

If your burner flames are blue and even, the burner is likely clean. But if they are yellow, you may have a dirty burner. Dust buildup over the summer makes this an important task to take care of at the start of winter. Cleaning the burner is easy and can be done with a vacuum cleaner – just make sure the power and gas are turned off first!

Problem #4: Too Much Clutter

This is another tip that may seem obvious, but the area around furnaces can easily turn into storage for many homeowners. Clearing the clutter out (especially any flammable substances) can help your furnace function much better, as well as reduce the risk of fire. And remember to vacuum and dust regularly around your furnace, since buildup can clog your filter.

Problem #5: Blocked Vents

Along the same lines, don’t forget to check each vent throughout your house to make sure they are open (especially if you have children – little fingers love to mess with them!) and unblocked by furniture. It’s best to leave at least 18 inches between furniture and vents for optimal airflow. Even something as lightweight as a curtain can obstruct heat flow. Making these adjustments can go a long way in helping your furnace properly warm your home.

Problem #6: Broken Safety Switch

For the furnace to operate properly, the door must be closed and the safety switch activated. If this switch needs to be replaced, first turn the power off and prop open the blower door. Wire in the new safety switch and test to make sure the furnace turns on when the door is closed.

Problem #7: Gas Furnace Blower Runs Continuously

A gas furnace blower that won’t shut off could indicate a larger repair is needed, but first check that your thermostat isn’t on a continuous fan setting. Another trick is to try turning the temperature down to see if that turns the fan off. The limit control switch may also need resetting or replacing.

Problem #8: Noisy System

A loud rumbling system isn’t normal, and could indicate any number of problems. For example, a rattling noise may mean loose panels need tightening, while a squealing noise could be a fan belt that slipped or needs replacing. If you hear a grinding sound, the motor bearings need fixing – a task best left to a furnace repair technician.

Problem #9: Dirty Flame Sensor

The flame sensor protects your furnace from unsafe fuel burning, so if it’s dirty it can cause a malfunction. The sensor is typically a rod found in the path of the burner toward the back of the furnace. If possible, it’s best to remove it from the furnace to properly scrub it clean of dust and residue. Don’t forget to turn off the power beforehand.

Problem #10: Lack of Maintenance

Last but certainly not least is maintenance. It’s crucial to your furnace’s health and longevity to keep up with regular tune-ups. Follow the manufacturer recommendations and have your system inspected by a professional to prevent minor repairs from becoming major problems.

When to Call in the Professionals

Remember, while furnaces can last a long time they can’t run forever. If your system is past its warranty, you’re not going to get the heating output Missouri winters require. The team at Metro Heating & Cooling can give you an accurate assessment and help you determine when furnace replacement is necessary.

Whether big or small, you can count on Metro Heating & Cooling to solve your furnace woes. Call (314) 845-5900 to schedule an appointment for heating installation or repair!

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