Is There a Thief in Your Ductwork?There are more than a million miles of ductwork in U.S. homes, and industry experts estimate that more than two-thirds of them are leaky enough to justify sealing or repair. Leaky ducts can significantly increase air conditioning and heating bills, dramatically reduce equipment capacity and performance, as well as result in potentially dangerous indoor air quality problems. In fact, duct leakage is responsible for many of the comfort complaints experienced by homeowners today.
Why Is Duct Leakage Important?Leaks in forced air duct systems are now recognized as a major source of energy waste in both new and existing houses. Studies indicate that duct leakage can account for as much as 25% of total house energy loss, and in many cases has a greater impact on energy use than air infiltration through the building shell. Just as important, duct leakage can prevent heating and cooling systems from doing their job properly, resulting in hot or cold rooms, and humidity problems. Worse yet, duct leaks can create air quality problems by pulling pollutants and irritants directly into the house.
Here are just a few of the problems resulting from duct leakage:
- Leaks in the supply ductwork cause expensive conditioned air to be dumped into the attic, crawlspace or garage instead of into the house.
- Return leaks pull outside air (hot in summer, cold in winter) into the duct system reducing both efficiency and capacity. In humid climates, moist air being drawn into return leaks can overwhelm the dehumidification capacity of air conditioning systems causing homes to feel clammy even when the air conditioner is running.
- Heat pumps are particularly susceptible to comfort complaints from duct leakage, especially during the heating season. Duct leaks can cause the air coming from heat pumps to feel luke-warm or even cold during the winter. In addition, leaky ductwork has been found to greatly increase the use of electric strip heaters in heat pumps during the heating season.
- Leaks in return ductwork draw air into the house from crawlspaces, garages and attics bringing with it dust, mold spores, insulation fibers and other contaminants.
- Household depressurization from duct leaks and imbalanced duct systems can cause spillage of combustion products (from furnaces, water heaters and fireplaces) into the house.
Advantages of Duct Leakage TestingYour company faces tough competition. It seems there is always someone who is willing to do the job cheaper and cut quality in the process. At the same time, homeowners commonly shop for the lowest price without understanding the difference a quality installation will have on their comfort and satisfaction. With a duct leakage performance test, you will be able to demonstrate the added value of your quality installation and repair services, and quickly differentiate yourself from the competition.
Close sales by selling quality, comfort and professionalism
Performance testing helps you create a reputation for quality and professionalism during the bidding process. Explaining the testing process and results to a customer demonstrates your understanding of the latest diagnostic and installation techniques. And of course, it lets the customer know you have taken the time to identify the problems and solutions for their building, and not just submitted a “one-size fits all” bid. It also creates peace of mind for your customer. With performance testing, you can explain that there is more to the job than just putting in a new metal box, and you can prove that you will do the job right.
Performance testing makes your jobs more profitable
One of the greatest benefits of performance testing is that you will more thoroughly understand the job before you begin. You will be able to identify duct leakage and other performance problems up front and provide better estimates for the work to be done. By reducing the guess work, you avoid unforeseen performance and comfort problems, size equipment more accurately, and reduce costly callbacks. Demonstrating duct leakage problems and the benefits of duct sealing lets you confidently recommend duct sealing services as part of your bid. This creates added-value for your customer and an added sale for your company.
Measuring Duct LeakageA duct leakage performance test involves pressurizing the duct system with a calibrated fan and simultaneously measuring the air flow through the fan and its effect on the pressure within the duct system. The tighter the duct system, the less air you need from the fan to create a change in duct system pressure. Testing procedures can be set up to measure only duct leaks which are connected to the outside, or to measure total duct leakage (i.e. leaks connected to the outside and inside of the house). Duct leakage measurements are used to diagnose and demonstrate leakage problems, estimate efficiency losses from duct leakage, and certify the quality of duct system installation.
- A Duct Blaster is used to directly pressure test the duct system for air leaks, much the same way a plumber pressure tests water pipes for leaks.
- The Duct Blaster fan is first connected to the duct system at the air handler cabinet, or a return grille. After temporarily sealing all remaining registers and grills, the Duct Blaster fan is
turned on to force air through all.
- Two different types of performance testing systems are used to measure duct leakage; a Duct Blaster® and a Blower Door.holes and cracks in the ductwork.
- The fan speed is increased until a standard test pressure is achieved in the duct system. A precise leakage measurement is then made using an airflow and pressure gauge connected to the Duct Blaster system.
- Estimates of efficiency losses from duct leakage can then be made from the leakage measurements.
- A theatrical fog machine can be used along with the Duct Blaster to inject a non-toxic fog into the duct system to visually demonstrate the location and extent of leakage in the ductwork.
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