In a preferred installation for the preheating of {HEAD ~ water} to {TAIL ~ a hot water heater}, the inlet second fluid will comprise cold tap water at line pressure and the thermosiphon loop of circulating heat transport liquid will normally be maintained at a positive static pressure of less than 10 psig  
In a preferred installation for the preheating of { HEAD ~ water } to { TAIL ~ a hot water heater } , the inlet second fluid will comprise cold tap water at line pressure and the thermosiphon loop of circulating heat transport liquid will normally be maintained at a positive static pressure of less than 10 psig
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