{HEAD ~ A fan} is mounted to the housing and is operably disposed, preferably, within {TAIL ~ the plenum} to draw air from the plenum and to exhaust the air outside of the housing 
{ HEAD ~ A fan } is mounted to the housing and is operably disposed , preferably , within { TAIL ~ the plenum } to draw air from the plenum and to exhaust the air outside of the housing
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH REL REL REL OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH