See below for Smoke Test Demo Video
The purpose of smoke testing the duct system at rough-in is to locate and patch duct leakage. This procedure involves temporarily sealing the register boxes and introducing theatrical fog into the duct system under slight pressure. (The black container sitting on the platform produces the theater fog.) When using this qualitative testing method, previously invisible leaks can be easily identified as the fog finds it way through any breaches in the duct system as show in the lower photograph. Performing this test at rough-in allows duct installers to immediately remediate any failures.
Although this test is not required for an ENERGY STAR, FGBC, or NAHB certification, it provides the only opportunity to correct duct leakage. Including this test as part of an energy-efficient, green home is a good idea for several reasons:
- Lower Energy Costs: Finding 25% leakage is not unusual and Progress Energy states that on average 30% of heating and cooling is lost to duct leakage. Keeping these figures in mind, making sure the duct system is as tight as possible can be the equivalent of increasing one SEER on the AC unit while preventing your homeowner’s hard-earned money from going up in smoke on a daily basis.
- Green Points for Including Smoke Testing: Opting to include this test contributes to the points available under the Energy Efficiency section of the NAHB green certification and to innovative points under FGBC green certification.
- Indirect affect on FGBC and NAHB Green Certifications: The amount of leakage in the duct system has a direct effect on the final HERS Index. A leaky system will result in a lower HERS index which can in turn lower FGBC and NAHB green certification points. The amount of duct leakage is measured via the Duct Blaster Test which takes place at completion and is required as part of a HERS rating.
In summary, the smoke test allows leaks to be detected and corrected equaling a better Duct Blaster Test result, equating to a higher HERS Index, and therefore contributing to green certification points (when a HERS score is part of the FGBC or NAHB certification selections).
- Indirect affect on ENERGY STAR Certification: An ENERGY STAR certification requires duct leakage to be ≤ 6 CFM to outdoors / 100 sq. ft. making this a pass – fail test. If this figure is not achieved via the Duct Blaster Test performed at completion, the opportunity to seal the ducts is lost and so is the ENERGY STAR certification. The smoke test provides the opportunity to detect and correct duct leakage to ensure a more positive Duct Blaster Test result.
To view at a glance how the HERS Index and all the various tests play a role in the FGBC, NAHB and ENERGY STAR certification programs Click Here