The Truth About Duct Tape and Air Ducts

As an expert in the HVAC industry, I have seen many homeowners attempt to use duct tape to seal their air ducts. While it may seem like a quick and easy solution, the truth is that duct tape is not a good product to use for this purpose. In fact, it can cause more harm than good in the long run. While adhesive tape may be able to adhere to tough surfaces and withstand a lot of things, it is not designed to withstand extreme temperature changes in air ducts. The heating cycles in your HVAC system can cause the adhesives on the tape to break down, leading to weakened seals and eventually causing the tape to fall off completely. Interestingly enough, duct tape was not originally designed for use in HVAC systems.

During World War II, it was used by the U. S. military for emergency repairs on the battlefield. It wasn't until later that it became known as duct tape and gained popularity in the movie industry for various uses on set.

However, contractors are not supposed to use it for structural purposes, such as duct suspension, although this legal restriction is often ignored. In a study conducted by Sherman and Walker, they tested the durability of adhesive tape by subjecting it to baking temperatures of 140-187 degrees Fahrenheit (60-75 degrees Celsius). In many parts of the United States, attic temperatures can easily reach 150 degrees Fahrenheit. The results showed that current adhesive tape production is almost completely ineffective at these temperatures. However, there is hope that adhesives and construction methods can be reformulated to perform better at higher temperatures. Fortunately, there are other products on the market that are specifically designed for sealing air ducts and meet industry standards for durability.

Both putty sealant and aluminum foil tape are good options for sealing air ducts. Despite its name, duct tape should never be used to seal air ducts. Not only is it ineffective, but it can also cause problems with your HVAC system. Instead, it is best to have a professional technician seal any leaks in your duct system using proper materials. They can also clean and insulate your ducts, which can improve energy efficiency and indoor air quality. While the Underwriters Laboratory (UL) has developed classifications for adhesive tape, these do not refer to longevity but rather characteristics such as strength and fire resistance.

This means that even if a tape is labeled as UL-approved, it may not be suitable for use in sealing air ducts. At the EETD of the Berkeley laboratory, an aerosol sealing system was developed and tested extensively. This system is designed to provide better adhesion and strength compared to options such as adhesive tape, eliminating the concerns we've mentioned so far. The ducts are held independently and all other possible leaks are carefully sealed, creating a more airtight system than most real-world systems. While transparent tapes, aluminum-backed tapes, putties, and aerosol sealants may provide good seals for a period of time, they lack the necessary strength to withstand the demands of an HVAC system. While the term "duct tape" may be confusing and based on historical misconceptions, it has unfortunately become a common source of air conditioning problems for those who try to use it for purposes for which it was not designed. Regardless of the sealant you choose for your ducts, it is important to choose a high-quality product and properly clean the application area before use.

As an expert in the HVAC industry, I highly recommend avoiding duct tape and instead opting for products specifically designed for sealing air ducts.