Air is forced through the tube bundle by either a draft induction blower located at {HEAD ~ the outlet end} of {TAIL ~ the tube bundle} or a forced draft blower located at the inlet 
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Air is forced through the tube bundle by either a draft induction blower located at { HEAD ~ the outlet end } of { TAIL ~ the tube bundle } or a forced draft blower located at the inlet
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 TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH