An apparatus and method for using {HEAD ~ a programmable variable speed motor} to indicate {TAIL ~ a clogged filter} while providing a constant airflow acrcss a wide range of restrictions 
to indicate
An apparatus and method for using { HEAD ~ a programmable variable speed motor } to indicate { TAIL ~ a clogged filter } while providing a constant airflow acrcss a wide range of restrictions
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH