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Why Is My Furnace Making Loud Noises?

Posted on: November 28, 2017

If your furnace is making new or unusually loud noises, they may indicate that there is a problem. Some noise is perfectly normal and expected when the furnace is running, such as pinging or popping as the ducts expand and contract, and some sounds, such as the blower fan spinning, may become louder over time as dust collects on the blades. Other noises may be cause for concern, and it can often be difficult to identify the source.

Common Furnace Noises and What Causes Them

Banging, pinging, or popping – Typically, these noises are caused by ducts as they expand and contract with changes in temperature and pressure. They can, however, be caused by poorly-secured ducts or airflow problems. Check for loose duct hangers, closed vents, or duct obstructions, as well as a clogged air filter. If a banging sound comes from the burners, there may be a combustion problem, such as delayed ignition or roll-out, and the system should be inspected immediately.

Tapping, thumping, or clicking – A blower fan belt that is loose or damaged can cause a fast tapping or thumping. Similar noises can be caused by loose parts or debris in the blower fan. Shut off the power, check the belt and fan, and tighten any loose fasteners or covers. Have the system inspected if there are no obvious problems.

Screeching or metallic sounds – Loud scraping, screeching, or metal-on-metal sounds may indicate a serious problem, like a bearing failure in the blower motor, a broken fan or motor mount, or a loose blower fan. Shut the system off and have it checked immediately to avoid damage.

Humming – A hum or buzz may simply be a loud transformer for the thermostat, or it could indicate a damaged transformer, electrical problems, or a failed blower motor. Have the system inspected if the sound continues or becomes louder.

Whistling – A clogged air filer or a duct obstruction can cause whistling as the air finds a different path to travel. Check for closed vents, debris in the ductwork, and a dirty or clogged filter. Leaks in the air ducts can cause a similar noise, and it if continues, you should have the ducts inspected and sealed.

Rumbling – The blower fan can often cause rumbling or vibration as it runs, and it may become worse over time as the fan collects dust. If the sound is coming from the burners, however, there may be a serious combustion problem. Shut the system off and have it inspected immediately.

Rattling – Loose fasteners, mounts, covers, and other parts can rattle or vibrate as the furnace runs. Shut off the power and tighten any loose components. If the sound continues or becomes worse, have the system checked by a professional.

If a sound becomes worse, you cannot identify the source, or you suspect there is a major problem, have a professional inspect your furnace throughly. Although most noises are normal or may be caused by relatively minor problems, some can indicate that there is major damage to the furnace, or that there is a serious safety problem.

Schedule Furnace Service in New Holland, PA with The Witmer Company

When you have a noisy furnace, contact The Witmer Company for fast, professional repairs anywhere in New Holland and the surrounding communities. We offer complete maintenance and repair services for furnaces, boilers, air conditioners, and more, as well as 24-hour emergency service. With over 75 years of experience, you can trust our certified technicians for all your heating and cooling needs.

Contact us at (717) 288-7163 for an appointment!

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