Sound traps are devices used to help absorb or muffle the sound generated within a heating ventilating and air conditioning or HVAC unit. The purpose of the sound trap is to minimize the amount of sound that travels through the ductwork, usually by projecting the sound back toward the point of origin. This approach helps to keep the interior areas in which the ductwork opens into different rooms relatively quiet and free of the roar that would otherwise come through the vents whenever the system was in operation.
One of the most simplistic designs for a sound trap is the insertion of what is known as an offset into the ductwork itself. Typically, the offset is composed of materials that are capable of absorbing and deflecting sound in a specific direction. It is not unusual for duct sound traps to be placed at several strategic locations throughout the system, beginning with one near the connecting point for the ductwork and the HVAC equipment. Other traps are placed at different points in the ducts, with the number varying based on the amount of ductwork required 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 of the heat pump and the ductwork leading into the structure. 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 several points throughout the home. When positioned properly, residents in the home will notice no more than a slight hissing as the system cycles on and begins to push hot or cold air through the vents and into each room of the dwelling.
A sound trap network in a commercial building would be somewhat more complex, especially if additional heat pumps are necessary to provide adequate temperature and humidity control to a number of stories in the building. Professionals can assess the size and type of equipment needed to maintain the proper temperature within the space, design the layout of the duct system, and determine how many AC soundtraps would be necessary to keep the system relatively quiet during operation.
Replacing a sound trap is normally a simple task. The duct is opened at or near the location of the trap and the device is removed. A new device is moved into position and secured in place, with care taken to make sure the new sound trap will not work loose after repeated buffeting from vibrations and air flow from the heat pump. While easy to replace, many systems can go for years without the need to switch traps, with some lasting longer than the heat pumps themselves.
By Malcolm Tatum