If your ductwork is made from fabricated metal sheets, chances are you might have heard popping sounds coming from the air conditioning unit. The noise usually scares clients since most of them believe that it is an early symptom of potential malfunctioning. Since the duct-work is an integral part of the entire system, you would be forgiven for thinking the same. However, you should rest easy knowing that such banging sounds are because of pressure changes in the duct system. The pressure differential causes the fabricated metal to move, thereby resulting in popping and banging sounds. However, the intensity of the noise depends on several factors that are highlighted in this article.
Duct Shape -- The most common duct shapes that sheet metal fabricators produce for HVAC purposes are round, rectangular, and square. When these are rated based on the amount of noise production, round ducts provide the least amount of sounds followed by square pipes, and lastly rectangular shaped tubes, which produce the loudest noise. The difference in the intensities can be attributed to the fluctuation in pressure handling threshold of each shape. For instance, round metal ducts are capable of handling pressure caused by temperature changes in the air within the ducts compared to the other two shapes. One way you can minimize the noise is by replacing a rectangular or square tube with a rounded one. Alternatively, your technician can line the insides of the ducts with duct liners to muffle the noise.
Metal Rating -- All metals have a gauge rating that demonstrates their strength. Metal ducts that have a lower gauge score are the thickest and strongest. As hot air passes through a solid metal conduit, the likelihood of the duct expanding is reduced and so is the amount of noise. On the other hand, metal pipes with higher ratings are thin and weak and are susceptible to natural expansion and contraction, which causes more popping noises. If everything else is functioning optimally and the noise persists, then your unit's duct metal gauge rating is high, and the only way to resolve the problem is by replacing it with a lower rated metal. Make sure you contact your HVAC technician though before you decide what to do.
Dust Size -- The size of metal ducts significantly dictate the amount of noise they produce. Smaller metal pipes cannot handle pressure difference efficiently, and you can physically see the movement on the piping. Any slight increase in temperature will cause a lowly rated duct to make a lot of noise. On the other hand, larger tubes allow even distribution of pressure was thereby reducing metal contraction and expansion. However, knowing the right size of metal ducts for your home is not an easy task since there are a lot of calculations involved. An expert in air conditioning systems will perform the calculations based on the size and requirements of your home. In the end, they will make the recommendation on how to expand your metal fabricated ducts.
Contact a sheet metal fabrication company for more information and assistance.