Have you ever been awakened from a sound sleep by duct noise? Do you hear rattling and clattering from the air-supply registers and walls? Duct noise is a common problem, but it may also be a serious problem, as far as high utility bills are concerned. There are three primary causes of duct noise:
- Friction or contact with other objects, such as framework or pipes.
- Stress in duct joints from expansion and contraction.
- Damaged, disconnected or loose ducts at joints, including air-supply registers.
Rattle, Clatter And Boom
Ducts sometimes come into contact with other structures, either from the house settling and shifting, or from poor duct installation. There should be a minimum of one inch between ducts and framework and other objects. This space is provided to allow ducts room for expansion and contraction, which is normal as conditioned airflow causes temperature changes to duct walls. Ducts expand both when heated, and when they return to normal temperature.
How To Stop The Noise
Noise caused by contact between ducts and framework may be muffled by placing padding at the friction points. If this doesn’t work, then a heating and cooling professional will need to assess the best solution, which may be repositioning ducts, or cutting into the framework.
Noise caused by stresses at duct joints may be solved by installing expansion collar joints. If one of the noises you hear is a very loud “boom,” this may be at the plenum and duct trunk connection near the furnace. The expansion collar should do the trick.
Rattling and clattering noises are often signs of damaged, disconnected or loose ducts. If this is the case, you may by wasting substantial heating and cooling energy. The average home loses more than 20 percent of conditioned air before it reaches the living space. Find the leaks and disjointed ducts, and seal them with mastic or aluminum tape.
Ducts aren’t always easily accessible. Use caution. If you have questions, contact Stack Heating & Cooling, and we’ll be glad to help. We’re a family-owned and operated company, and we’ve proudly served northeast Ohio since 1976.
Our goal is to help educate our customers about energy and home comfort issues (specific to HVAC systems). For more information about duct noise and other HVAC topics, download our free Home Comfort Resource guide.