How to Prevent Leakages in HVAC Duct Work

How to Prevent Leakages in HVAC Duct Work

Illustrations showing How to Prevent Leakages in HVAC Duct Work

Preventing Leakages in HVAC Duct Work

The ducts of a forced-air heating and cooling system are an important part of an HVAC (Heating, Ventilation and Air-Conditioning) system. According to the U.S. Department of Energy, between 25 and 40 percent of conditioned air is lost through leaks and poor joints in HVAC duct work. Ducts that lose just 20 percent of conditioned air make a system work 50 percent harder. The result is energy loss, high utility bills and an uncomfortable indoor environment.

Proper attention must be given to duct work system for new construction and for existing installation as Retrofit.

In a new construction, an HVAC design engineer takes the lead to ensure HVAC duct work tightness by designing an effective HVAC system, accounting for duct leakages using appropriate percentages that comply with building codes, standards and research. He then works with contractors to ensure HVAC ducts are fabricated and installed to specifications based on the HVAC design’s pass/fail criteria.

The way to minimize loss of conditioned air is to place HVAC duct work within a building’s conditioned space instead of in basements, walls, attics and crawl spaces. In modern design schemes, ducts can contribute to the decor. Ducts can also be placed in false ceilings, below floors or in sealed chases. Efficient installation includes sealing joints with proper materials such as mastic or foil-backed tape to minimize leaks.

Retrofitting an existing duct system should be undertaken by HVAC professionals. An experienced HVAC engineer knows how to balance airflow between supply and return air ducts. A poorly balanced system may force conditioned air into unconditioned spaces or allow unconditioned air to be pulled into the system. This reduces efficiency.

An HVAC professional carry out smoke test to detect leakages in the duct. Flexible ducts that are crumpled or tangled should be straightened. If flexible ducts are crushed or in poor condition, they should be replaced. Leaks and poor joints can be sealed with mastic, aerosol sealant or foil-backed tape. After sealing, ducts should be insulated with foil-backed insulation of an R-value of at least 6.


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