Duct Blaster Testing
The Duct Blaster is a device that uses pressure testing to
find the amount and location of air leakage in a duct system.
To do the test, we seal all the outlets except for one on the
return side of the system (the side that returns stale air to
be reconditioned). The Duct Blaster is connected to that
last one and then turned on to blow air into the ducts. The
air goes through the return ducts to the air handler and then
through the supply ducts. If the whole system is very tight, it
doesn't take much airflow through the fan to pressurize the
ducts. If you have a big leak, like a disconnected plenum or duct, it will be impossible to
pressurize the ducts adequately. That would be like trying to put air in a tire that has a big
hole in it.
The process yields quantitative results because testing requires two pressure
measurements: one inside the ducts and the other inside the fan. The first allows the
tester to compare results from different systems by always pressurizing to the same level.
The second measures the airflow in the fan when that level is reached. As mentioned
above, tight ducts mean low airflow, and leaky ducts require lots of airflow.
Pressurizing only the ducts determines the total leakage. That includes the air that
escapes into the conditioned space and the air that leaks to outside of the building
envelope (i.e., the attic or crawl space). The latter is the most important part because you
derive no benefit from it. To separate it from the total leakage, we will pressurize the
house to same level as the ducts with the Blower Door. Then, when the Duct Blaster
brings the ducts up to the required pressure, none will leak to the inside of the house
because it's at the same pressure as the ducts. The fan only has to blow enough air in to
make up for the leakage to the outside, and that's the amount that's important.
In a tight air distribution system, the leakage to the outside (in cubic feet per minute, or
cfm) will be 5% or less of the square footage of the house. Most new installations start at
about 15 to 20% and go downhill from there. At those rates, a third of the heating and
cooling bills could be a direct result of duct leakage.
After performing Blower Door and Duct Blaster tests to determine the amount and
locations of air and duct leakage, we can seal up the leaks that we find. Upon completion,
the house and/or duct system will perform much better, and your heating and cooling bills
will be reduced.
Call now, to set up an appointment (989)414-6699, or fill out our questioner and we will
contact you at your convenience.
"Your energy conservation experts"
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