Whether it's a freezing winter morning in Minneapolis or a torrid summer afternoon in Phoenix, air leaking from ducts and air handlers can bring a little welcome relief to a home inspector braving the elements in an unconditioned attic. For clients, however, the leak that brings relief to the home inspector can represent a costly defect. Poorly installed HVAC ducts cost our clients money and reduce their comfort every minute the HVAC system runs. Installation errors can also contribute to moisture problems and related fungal growth.
Flexible HVAC duct (flex duct) is the most common material used in modern residential HVAC duct systems. While other materials such as sheet metal and duct board are still used, the cost advantages of flex duct make it a popular choice for many builders. Unfortunately, the factors that give it a cost advantage--mainly less skilled and less expensive labor--also make installation errors more likely when compared to other materials.
Estimates of efficiency reductions caused by poorly installed ductwork range from 10 percent for good systems up to 40 percent in poor systems. Assuming a modest annual household heating and cooling bill of $1,200 ($100/month), between $100 and $480 in utility costs alone could be wasted each year. This excludes costs for increased system maintenance and reduced system useful life, and excludes the environmental costs of pollution caused by generating the power to run inefficient systems. Adding these costs together defines a problem that deserves attention.