Static pressure is the resistance air encounters as it is traveling through a duct system. This measurement is often compared to taking the “Blood pressure” of your hvac unit. We measure the entering and exiting static pressures in which every manufacturer has a specific tolerance. As air flow increases, the static pressure decrease and vise-versa. High static pressures are signs of improper duct sizing, blockages/kinks, closed dampers, dirty coils/blower wheels, and hot and cold spots throughout the home. Low static pressures are signs of leaky ducts, low fan speeds, and separated ducts. Issues like these can cause premature equipment failure, indoor air quality issues and noisy systems. The external static pressure value should not exceed 20 percent of the indoor blower’s rated capacity. If you are not comfortable, please call us today for a Duct tightness verification test (Duct blast) or a Blower door envelope test.