Duct Leakage Testing
Breen Design – Residential HVAC Calculations & Designs
Why Air Duct Leakage Testing is Extremely Important
Most buildings today are suffering from some percentage of air leakage in their ductwork. This is why air duct leakage testing is extremely important.
What Is Duct Leakage Testing?
There are a lot of Colorado counties and jurisdictions that have a requirement for duct leakage testing. Duct leakage testing is to evaluate how well a home’s duct system can hold air. The idea is that if more air leaks out of the duct system, there will be more energy loss.
If the duct system is found to meet the standards of today’s building codes, a pressure test is performed on the duct system itself.
The requirements come from the 2015 IECC energy codes and they are stated as follows:
Duct testing can be done before the construction starts or after the construction is complete. Both cases have the same requirements. The system will need a leakage rate of less than 4 CFM per 100 square feet of the home. This is commonly referred to in the industry as a 4% leakage rate.
The Duct Testing Process
All of the duct openings need to be sealed in order for the testing to take place. All supply and returns registers are included. We do this by using large tape to close the openings. It can take a while as we try to create the best seal. Our fan is sealed and placed into the air handler.
The fan runs to make the duct system go to -25 pascals. The amount of air moves through our fan and is measured. Under 25 pascals of pressure, the number is known as [email protected] This CFM number is the number to be used in the calculation or scoring.
How To Prepare For The Test In Your Home
- Make sure your contractor is aware that the test is needed before they put the system together. This usually ensures that they use enough products during their installation.
- Zip ties are more likely to leak around flexible ducts. It can be very helpful to minimize these junctions in attics.
- Use plenty of duct sealant material around the corners and edges around corners.
- The air handler has seals around it. Poorly sealed ductwork is a common sight around the back of the furnace.
- An airtight system can be used for the filter slot. It’s a good idea to have a weather-sealed door when the door is not open.
- The test should be done so that the problem areas can still be accessed so it’s recommended to test while the property is in roughed in construction status.