For instance, hot tubs and swimming pools often maintain a constant circulation of water through {HEAD ~ a filter and heater assembly} to clean and heat {TAIL ~ the water} passing there through 
to heat
For instance , hot tubs and swimming pools often maintain a constant circulation of water through { HEAD ~ a filter and heater assembly } to clean and heat { TAIL ~ the water } passing there through
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH