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Knock It Off: How to Reduce Air Duct Popping and Knocking Noise

by vscontent on September 22, 2017

Knock It Off: How to Reduce Air Duct Popping and Knocking Noise


Haunted house or noisy air ducts? Imagine trying to go to sleep, reading a ghost story, or watching a horror movie and all of a sudden you hear a rush of air and loud knocking, banging, and popping. It’s enough to put anyone on edge.

Whether loud ductwork scares you or not, nobody wants to hear loud popping and knocking noises in their home.

While all HVAC systems make some noise when they are on, when there is excessive noise, such as popping, knocking, and banging, it can indicate a problem.

If every time you turn on the heating or cooling system, the air ducts start popping and banging, read the rest of this article for tips on how to reduce and even stop the noise entirely.

Why Are My Air Ducts Popping and Banging?

One of the main causes for these loud noises are differences in pressure between the supply and return ducts. Another common cause is expansion and contraction due to changes in temperature.

Oil Canning – When the walls of your air ducts move in and out due to pressure differences, you may hear a rumbling, popping sound. This is often referred to as “oil canning.”

Expansion and Contraction – If you only hear the banging and popping noise when you turn on the furnace, it could be because you have warm air flowing through cold ducks, which can make the metal expand and “pop.” If you hear creaking, your ducts may be expanding near wood.

How to Reduce Air Duct Noise

While nobody will be able to entirely get rid of the noises your HVAC system makes, there are several things you can do to reduce loud air duct noises.

  1. Clean, Seal, and Insulate Ductwork

While it may cost some money, the most effective solution short of replacing your entire duct system is to clean, seal, and insulate the ductwork. This will reduce pressure differences and soften the effects of any expanding and contracting metal ducts. Contact your HVAC company about duct cleaning, sealing, and insulation solutions, such as acoustic duct liners, Aeroseal duct sealing, and fiberglass insulation. Always hire a professional for ductwork cleaning work.

  1. Check Dampers and Actuator

Dampers can either be open or closed. Check the dampers on the supply side of your ductwork and try opening them up one at a time to see if this reduces the popping and banging noises. You can also adjust the actuator inside of the duct dampers up or down to reduce the duct noises. If you don’t know how to do this, contact your local HVAC technician.

  1. Change Your Air Filter

A clogged airflow severely restricts airflow. By changing out your air filter you can help return proper airflow to the entire system. You should clean or replace your air filter every 30-60 days anyway for improved HVAC efficiency and better indoor air quality.

  1. Circular Vents vs Rectangular Vents

Circular vents tend to make a lot less noise than rectangular vents. This is because the walls of rectangular vents can move in and out a lot easier. Circular vents have more support and thus are less likely to move and make noise.

  1. Schedule HVAC Maintenance

A dirty and inefficient HVAC system can cause unnecessary HVAC noise. Make sure you schedule furnace/heating maintenance every fall and air conditioning maintenance every spring. Sign up for a home maintenance plan so you never forget this important home maintenance task.

  1. Replace Your HVAC System with Ductless Zoning Solutions

You can get rid of noisy air ducts entirely by installing an HVAC system that doesn’t need them in the first place. Learn about ductless mini-split HVAC systems.

furnace and air conditioning maintenance tune-up (precision heating and cooling service)

Related Resources:

For more information on HVAC maintenance plans, don’t hesitate to contact Pacific Heating & Cooling.

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