For the finned tube coil design, there is a performance maximum corresponding to an eight- or ten-row coil, above this the fan and pump motor energy consumption increases substantially and seasonal efficiency starts to decrease. The main cause of increased energy consumption lies with the fan, for the same face velocity, fewer coil rows will decrease air pressure drop and increase water pressure drop. The total energy consumption will usually be less than that for a greater number of coil rows with higher air pressure drops and lower water pressure drops.