The heat pump in accordance 1 or 2, wherein said {TAIL ~ second reversing means} is {HEAD ~ a four way valve} 
The heat pump in accordance 1 or 2 , wherein said { TAIL ~ second reversing means } is { HEAD ~ a four way valve }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD