The first four way valve is used to direct refrigerant periodically to flow in a series through each coil when that coil is operating as a condenser and to receive {HEAD ~ refrigerant} flowing in {TAIL ~ parallel circuit} when a coil is operating as an evaporator 
flowing in
The first four way valve is used to direct refrigerant periodically to flow in a series through each coil when that coil is operating as a condenser and to receive { HEAD ~ refrigerant } flowing in { TAIL ~ parallel circuit } when a coil is operating as an evaporator
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 OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH