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 refrigerant flowing in parallel circuit when {HEAD ~ a coil} is operating as {TAIL ~ an evaporator} 
is operating as
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 refrigerant flowing in parallel circuit when { HEAD ~ a coil } is operating as { TAIL ~ 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 OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL