Sunday, June 5, 2011

Duct Blaster video

This is a pretty decent little video on running a duct blaster test at the rough-in phase of a new construction home.  According to Mike Uniacke, there are 3 types of ducted distribution systems: un-sealed systems, sealed systems, and systems that are sealed and TESTED.  The testing of ductwork is a critical component of all 3rd party rating/verification programs, such as Energy Star, LEED, etc.

I think one of the most telling components of this video comes toward the very end.  Note the massive amount of air leakage that is present at the air handler itself.  This is the rule, not the exception.  It takes a very careful installing technician to adequately seal the air handler of leaks. 

When prioritizing duct sealing opportunities, we typically start with leaks that are closest to the blower.  We do this because the leaks in close proximity to the blower are under the greatest pressures.  Since they are under the greatest pressures, they leak the most, and we want to seal up the areas that leak the most.  Not rocket science here.

I should probably take a step back.  The first areas that we would want to duct seal are return-side leaks that create negative pressure fields in CAZ zones which backdraft combustion appliances.  Then the ones closest to the blower.

Watch the video, as there are some good pointers there.... 

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