Fuel-combusting heaters rarely offer whisper-quiet operation. After months of sitting dormant, the furnace in your Mesa, AZ, home might start up with an audible humming sound. It may even make several banging or clanging noises as your ducting undergoes heat-related expansion and contraction. Many noises are a normal and expected part of furnace operation, especially when they’re unobtrusive and have always been around. However, if you hear metal-on-metal grinding, loud booming, or persistent screeching or rattling, you should turn your furnace off and seek help from a professional. The following are six furnace noises that homeowners should never ignore.

1. High-Pitched Shrieks

If you haven’t had your furnace tuned up in a while, there’s a good chance that it has loose, worn, or missing parts. After all, these heaters are subjected to a lot of stress during the heating season. Dramatic temperature fluctuations, constantly moving parts, and fast-moving air all take their toll. When furnaces shriek during their heating cycles, it’s often an indication of:

  • Worn or slipped fan belts
  • Loose or damaged bearings
  • Jammed fan blades
  • Insufficient lubrication

During the annual furnace maintenance service, professionals will lubricate all moving parts. They also inspect and replace missing and broken components while tightening up loose connections. Not only do these measures prevent the development of loud shrieking and squealing noises, but they also optimize the efficiency of furnaces. Having your furnace tuned up annually could help lower your energy bill and extend the lifespan of your heating equipment.

2. Rhythmic Clanging Sounds

When your furnace’s fan motor turns on, loose components often get blown about on their moorings. With each fan blade cycle, they might come in contact with hard, nearby surfaces. Rhythmic clanging often means that these components simply need to be tightened or adjusted. However, when clanging noises become louder and more erratic, loose components have come completely off and are tumbling wildly around in the fan motor’s housing. Once loose, these parts can damage other fan components. They can also jam the fan’s blades and cause your furnace to short-cycle and overheat.

Tightening a loose component might seem like an easy task, but this is best left in the hands of a professional. If your furnace is still under its manufacturer’s warranty, opening it and tampering with moving parts could void your warranty.

3. Scratching and Clawing Sounds

If you hear frequent scratching and clawing sounds after turning your furnace on, you may have rats, mice, or other pests in your HVAC air ducts. During the winter months, small animals enter HVAC systems to take advantage of the warmth and shelter they provide. Air ducts offer the perfect hiding place, and in some instances, they may even offer easy access to water or food.

Having rodents or other pests in your ducting can lead to structural duct damage, including ripped, torn, perforated, or collapsed sections. It can also greatly diminish your indoor air quality. Pests often leave behind feces and food, filling your home with dangerous airborne pathogens.

Pests and the duct damage they cause can additionally decrease the lifespan of furnaces and set the stage for costly repairs. To correct the problem, you’ll need to deal with the infestation first and have a licensed HVAC company fix any damage that was done. You should then have your air ducts professionally cleaned and disinfected.

4. Rumbling Noises Paired With a Yellow Pilot Light

Many older, gas-fired furnaces have pilot lights rather than electronic ignition switches. If your furnace was manufactured and installed before 2010, be on the lookout for loud, rumbling noises and yellow pilot light flames. Pilot light flames should always be even, steady, and bright blue. Yellow, orange, red, or guttering flames mean that fuel is being incompletely combusted. More importantly, they’re often a sign that carbon monoxide gas is being released.

If your furnace starts to rumble while it’s on, always take the time to check for blue pilot light flames. If you spot any other color, turn the furnace off and give a professional a call.

Problems at the pilot light sometimes mean that the furnace’s flame sensor is dirty, bent, or poised to fail. They can also be the result of blocked or dirty air intake valves or other maintenance-related issues. As with high-pitched shrieking noises arising from insufficient lubricant and loose or damaged parts, malfunctioning pilot lights can often be prevented or resolved with professional furnace maintenance.

5. Scraping Noises

Scraping and screeching sounds are usually an indication of metal-on-metal contact. They mean that something is out of alignment, knocked or broken loose, jammed, or failing. More often than not, the culprit is a bent, misaligned, or jammed blower fan blade. As with all equipment that has damaged components, continuing to use your furnace with broken fan blades can turn a small and relatively low-cost repair into a major project. The best way to limit your spending is by turning your furnace off and scheduling urgent heater repairs.

6. Squeaking, Chirping Sounds

Squeaking and chirping sounds aren’t normal furnace noises. In rare instances, they may indicate a noisy pest in HVAC ducting. More commonly, they mean that the blower motor is misaligned. Severe misalignment can cause the blower motor’s mounting plate to connect with the blower wheel and produce a sharp chirp or squeak. To prevent accelerated wear and a full-on furnace breakdown, shut your heater off and have the noise investigated. Your furnace may need little more than added lubricant or to have its blower motor adjusted.

Aging Furnaces and Loud Noises

Advanced age is one of the top signs that it’s time for a furnace replacement. Fuel-combustion furnaces typically last between 15 and 20 years. Many electric models can last up to 30 years. By this time, most furnaces have already lost more than half of their efficiency, and they’re usually a lot louder than they used to be. If you have a furnace that’s two decades old or older, it may be a good idea to have a newer and more efficient model put in.

Declining performance and increased noise aren’t the only drawbacks of hanging onto an older heater. An old, outdated furnace can significantly diminish your indoor air quality. With fuel-combusting furnaces, there’s also an increasing risk of carbon monoxide leaks as their fuel combustion chambers and heat exchangers wear down.

Replacing an old, noisy furnace is a great way to protect the health of your loved ones and keep your home comfortable. If you aren’t quite ready to let your aging heater go, you should take extra care to have it professionally maintained on a regular basis. Diligent, routine maintenance will limit the occurrence of noisy, functional problems. It will also give our technicians the chance to inspect and test your carbon monoxide detectors and your furnace’s failsafe measures.

Honest Air Conditioning is proud to serve Mesa, AZ, and the surrounding communities. You can count on us for superior workmanship, competitive pricing, and solid guarantees. We offer furnace, heat pump, and air conditioner maintenance, installation, and repairs. We also provide indoor air quality services and an exciting selection of top-rated HVAC products. To schedule an appointment, contact Honest Air Conditioning today.