In {TAIL ~ one embodiment}, {HEAD ~ the pipe} itself forms a part of the heat exchanger while in another embodiment, the heat exchanger is closed so as to form a heating chamber 
In
In { TAIL ~ one embodiment } , { HEAD ~ the pipe } itself forms a part of the heat exchanger while in another embodiment , the heat exchanger is closed so as to form a heating chamber
REL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD 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