GOC665945 - Consultant - EWA-Installing VFD on Supply and Return Fan

The main AHU in the penthouse mechanical room currently has inline axial supply and return fans moving air to and from the VAV box zones spread throughout the JD Higinbotham building. Both supply and return fans have variable inlet vanes which modulate open and closed to adjust the system airflow to meet the variable building cooling and ventilation demand loads.These inlet vanes work well in adjusting to the changes in building demand loads however they are considered in-efficient and older technology by current standards. With this type of pressure control design the fan motors run at constant speed and near to full load at all times whether or not the actual building demand load drops dramatically. It is recomned to install VFD's on the supply and return fans (SF-1, RF-2) not currently controlled by VFD. Both fans have been intalled in penthouse mechanical room and provide services for 1-4th floor.