What’s a sound trap?

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Sound traps are used in HVAC units to absorb or muffle sound. They are placed strategically throughout the duct system to minimize noise and can be easily replaced if needed. Commercial buildings may require more traps than residential homes.

Sound traps are devices used to help absorb or muffle sound generated within a heating, ventilation and air conditioning or HVAC unit. The purpose of the sound trap is to minimize the amount of sound traveling through the duct, usually by projecting the sound back towards the point of origin. This approach helps keep indoor areas where ductwork opens into different rooms relatively quiet and free from the rumble that would otherwise come from the vents whenever the system is running.

One of the more simplistic designs for a sound trap is putting what is known as an offset into the duct itself. Typically, offset is made of materials that can absorb and deflect sound in a specific direction. It is not uncommon for duct acoustic traps to be placed in several strategic locations throughout the system, starting with one near the connection point for ductwork and HVAC equipment. Other traps are placed at different points in the ducts, with the number varying based on the amount of ducts needed to adequately heat and cool the interior space.

With a home heating and cooling system, there may be a single HVAC sound trap located near the junction between the heat pump and the pipes leading into the facility. This is especially true for a one-story home with no more than a couple of bedrooms. Two-story dwellings will likely include additional sound trap offsets at different points in the house. When placed correctly, the home’s residents will notice only a slight hiss as the system powers up and begins pushing hot or cold air through the vents and into each room of the home.

A network of acoustic traps in a commercial building would be a little more complex, especially if additional heat pumps are needed to provide adequate temperature and humidity control over a number of floors in the building. Professionals can evaluate the size and type of equipment needed to maintain the proper temperature within the space, design the duct system layout, and determine how many AC sound traps would be required to keep the system relatively quiet during operation.

Replacing a sound trap is normally a simple task. The conduit is opened at or near the trap location and the device is removed. A new device is moved into position and secured in place, care being taken to ensure that the new acoustic trap does not become loose after repeated vibrations due to vibration and airflow from the heat pump. While easy to replace, many systems can last for years without the need to change traps, with some outlasting the heat pumps themselves.




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