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7 Common Furnace Issues

fixing gas furnaceProblems with your furnace tend to occur when you least expect them: When temperatures plunge below freezing, in the middle of the night or during the holiday season when other activities and tasks are on your mind.

Furnace issues typically fall into two groups: The fixture needs regular maintenance to perform optimally or a part no longer works, calling for repairs. Especially with winter around the corner, here’s what you should consider.

Clogged Filter

You turn on the furnace and expect a blast of warmth. Instead, you hear it working but barely feel the desired effects. Generally, this issue comes down to a furnace’s performance and accumulations from the spring and summer season.

In this scenario, you’re likely dealing with a dirty, clogged filter. If you check the filter, light should be able to pass through. If it’s covered in dust or you notice a strange smell whenever you turn the furnace on, the filter needs to be cleaned or replaced.

Accumulated debris blocks the flow of air, causing your furnace to work harder and increasing the risk it will overheat, due to the buildup of pressure. In this scenario, your furnace may shut off completely.

Debris In the Burner

Dirt and debris do not just build up in the filter – they can also accumulate on the burner and affect the furnace’s flame quality. If the flames appear even and blue in color, the burner is clean enough for use. A yellow hue indicates the presence of outside elements.

Another issue related to the changing seasons, dust, condensation and soot can build up on the burner during the summer months and should be cleaned off or replaced at the start of the fall season.

Long term, a dirty burner decreases your furnace’s performance, affecting the flow of natural gas and the combustion process. Eventually, you’ll hear a strange noise every time you turn the furnace on and feel less heat being generated.

Blower Isn’t Working

Debris can also affect the blower, which is designed to take the heat generated by the furnace and move it through the ducts to the rest of the house. Poor maintenance is often behind decreased performance.

Along with debris accumulation, the blower may need to be oiled, which should be done once a year, or a malfunctioning limit switch prevents it from turning off. Annually, have a technician inspect your furnace to assess its performance and determine if the blower needs any repairs.

Vent Issues

Lack of heat might not even involve the furnace itself – something could be blocking one of the vents. At the start of the season, check all vents inside and out to make sure furniture, curtains, fabrics and other objects are not blocking the openings.

Furnace Won’t Shut Off

When it comes to heating your home, you want a degree of control. A furnace that won’t shut off creates a constant delivery of heat. A couple of factors could be behind this issue:

  • Limit Control Switch: The limit control switch ultimately controls the blower, which diverts air to the heat exchanger, where it’s heated and pushed through ducts into your home. A limit control switch that’s damaged or needs to be reset allows this process to go on without interruption and may prematurely cause the blower to wear out.
  • Thermostat: Leaving the thermostat on the continuous fan setting can prevent the furnace from shutting off completely.

Strange Noises

An odd noise generally means a part is failing and needs to be replaced. You could be dealing with one of the following:

  • Ball Bearings: Worn out ball bearings may be behind a scraping or grinding noise while your furnace is in use.
  • Blower Belt: If this part wears down, loosens or moves out of place, you may start to hear a squealing noise.

Cracked Heat Exchanger

A cracked heat exchanger not only impacts performance but also poses a significant health risk, causing carbon monoxide to build up in your home. You may notice a strange, sour smell, see water on the surrounding floor or spot soot buildup inside of your furnace.

You may also start to experience symptoms of carbon monoxide poisoning, including headaches, nausea and feeling like you have the flu.
Before winter officially arrives, make an appointment with our HVAC technicians to examine your furnace and make repairs. To get started, contact MJ Fahy & Sons today.