Monday, April 18, 2016

Leaking Ductwork May Be Cooling and Heating Your Attic

  • Old ductwork may not have been properly sealed when installed, or the seals have failed over time.  This is equally possible for nearly new ductwork.
  • Improperly installed, or undersized ductwork may result in airflow reduction (less air coming out than going into the system).
Determining if this condition exists is easy.

When looking for HVAC service

What Does A Static Air-Pressure Test Tell You?

Static pressure is the measure of the Air Leakage OR Airflow-Resistance within the duct system. 
How An Air-Pressure Test Works:
 Al's Plumbing, Heating and Air Conditioning takes two pressure readings:
  • The air pressure entering the system
  • The air pressure leaving the system.
  • We add the two pressures together for the total pressure.
Al's Plumbing. (2012, March 3). Static Pressure Testing, Ductwork Pressure Testing Al's Plumbing. Retrieved April 18, 2016, from
On the Supply-Air Side (air coming out the ducts in the rooms):
  • If the pressure reading is Too Low, there is air leakage in the ductwork bringing air to the rooms.
  • If the Static Air-Pressure reading is Too High, there is restricted airflow in the ductwork bringing air to the rooms.
Corrections may include resealing the Supply-Air ductwork, or eliminating airflow blockages.   On the Return-Air Side (the large vents which have no shut-off lever):
  • If the Static Air Pressure reading is Too LOW -- there is a disconnected return-air duct, or ductwork is too large.
  • If the Static Air-Pressure reading is Too High -- there are not enough return air ducts or ductwork is too small.
Corrections may include adding more Return-Air ductwork, or increasing the size of the Return-Air duct work to increase airflow Here are photos showing Supply-Air Problems:

Unsealed pipes carrying air to rooms resulting in air leakage.

Improperly installed (compressed) ductwork resulting in an air-flow restriction.
The Goal Is Simple:
The amount of air coming out of all the rooms' ducts should be quite similar to the amount going into the return-air vents (adjusting for the airflow resistance caused by the furnace itself -- that information is provided by the furnace manufacturer) Learn how High-Merv Air Filters can dramatically reduce system air flow High MERV Filter and System Air Flow

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