In the second operational position, the second register provides for residential used air intake in the second chamber and expulsion of the air leaving {HEAD ~ this second chamber} into {TAIL ~ the atmosphere} 
In the second operational position , the second register provides for residential used air intake in the second chamber and expulsion of the air leaving { HEAD ~ this second chamber } into { TAIL ~ the atmosphere }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL