a horizontally movable grid as {HEAD ~ flow control device} located below {TAIL ~ the heat exchanger} and 
located below
a horizontally movable grid as { HEAD ~ flow control device } located below { TAIL ~ the heat exchanger } and
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH