June 23, 2015

Without proper duct maintenance, residential ductwork is all too often the weak link in the chain of HVAC energy efficiency. The Department of Energy reports that at least 20 percent of the air conveyed by ducts never reaches the rooms it’s supposed to keep comfortable. That’s cooling and heating—and energy dollars—lost due to leaks, thermal deficiencies, and airflow obstructions. A great deal of residential ductwork installed in the past wasn’t fabricated to last the life of the home. Duct maintenance performed by a qualified HVAC technician is critical to keep airflow high and energy expenses low.

Air Leakage

A pressure test uses a blower fan and sensors linked to a computer to accurately quantify the extent of duct leakage. This process also includes techniques to pinpoint leaks for later sealing. Air leaks frequently occur at poorly sealed joints or where segments have become partially disconnected. To reduce leakage, joints must be sealed with mastic, then permanently secured with screws and wrapped with aluminum tape. Extensively rusted or corroded segments will be cut out of the span and a new section inserted. Where small leaks are too numerous to repair individually, injecting an aerosol sealant into the duct coats the interior surface.

Thermal Transfer

When ducts are routed through a very hot attic or chronically cold basement or crawl space, heat gain or loss through the duct surfaces can be substantial. To cut costs during original construction, ductwork installed in acute temperature zones often wasn’t adequately insulated. Even if it was insulated, the insulation may have deteriorated over time. Duct maintenance includes installing or restoring duct insulation to a recommended level of at least R6.

Airflow Issues

Insufficient duct airflow opens a Pandora’s Box of efficiency and comfort issues that can be addressed by proper duct maintenance. In addition to clogged air filters, dirt and dust accumulation inside ductwork increase air friction and inhibit adequate flow. Also, sagging segments of the flexible ducts may collapse over time and block the passage of air.

To schedule duct maintenance by a qualified HVAC technician in Phoenix and Scottsdale, contact Wolff Mechanical.

Our goal is to help educate our customers in the Phoenix Valley area of Arizona about energy and home comfort issues (specific to HVAC systems).

company icon