Can the existing duct and SCHW systems be reused in a retrofit project with Dadanco units replacing the original induction units?
Yes. The primary air flow will be the basis of the new selection for the Dadanco units. This means the duct velocities will remain the same, and hence the duct static pressure losses. The overall system static will reduce when the changeover is complete and no old units are operational and require the original higher pressure at their locations. The secondary water flow will remain the same, although there have been proposals to increase it by 10% to cater for increased room loads. This decision is for the designer when deciding if the increase in pump power is acceptable in the overall energy equation. With the range of coils available in the Dadanco units and the secondary air flows achieved with the new nozzles, this usually means a significant improvement in total unit capacity, with the original fluid flows and infrastructure.
