Popping
When the blower cycles on and pushes air through the ducts, the increase in pressure against the metal can cause a popping noise. This type of sound is completely normal. It's often more noticeable when ducting is new or just cleaned, since accumulating dust has a muffling effect.
Whistling
If the ductwork is leaky, escaping air can produce a whistling sound when the blower is running. Having the ducting properly sealed and insulated can stop the noise, and prevent unnecessary energy losses that rob you of up to 30 percent of the equipment's heating or cooling output.
Banging and Rattling
Loose or disconnected duct sections can bang or rattle when the heating and cooling equipment is operating. Checking all the joints, correcting any poor connections and then sealing the ducts using mastic or metal-backed tape can solve the noise issue and help avert future problems.
Scraping
Metal ducts expand in response to temperature changes. If enough space wasn't allowed around the ducts during installation, you may hear a scraping noise when the expanding metal rubs against floor joists or other building components.
Whooshing or Roaring
While it's normal to hear a low roar or whoosh through the ducts when the air handler is running, a sudden increase in noise volume warns you that airflow has become restricted. If replacing the system's air filter doesn't help, contact an HVAC professional to identify the cause before airflow loss issues lead to equipment damage.
Scuttling
If you're hearing scuttling sounds, rodents may have taken up residence in the ducts. Contact an exterminator to get rid of the infestation, then schedule duct cleaning to remove any contaminants.
For expert advice about the cause of duct noises in your home in the Route 495/128 area of Massachusetts, contact Rodenhiser Plumbing, Heating & Air Conditioning.
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