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