Motorized Volume Damper - Modulating Motorized Volume Damper - Modulating NickParker (Electrical) (OP) 5 Mar 18 16:46 Hello All, Why this motorized volume damper before the Pressurization unit and after the blower fan is of modulating type? Why is it not just open or close type? RE: Motorized Volume Damper - Modulating dbill74 (Mechanical) 6 Mar 18 13:27 Find and read the sequence of operation. You have not given enough information as it is to get a good answer. RE: Motorized Volume Damper - Modulating Drazen (Mechanical) 16 Mar 18 01:07 what is el-002? RE: Motorized Volume Damper - Modulating ChasBean1 (Mechanical) 17 Mar 18 06:01 Typically I'd like to see those one step simpler for fans in parallel: back draft type. That does not mean this design is flawed. When in doubt of intended sequences the modulating damper has some preferable characteristics over its two-position counterpart. There is more versatility. RE: Motorized Volume Damper - Modulating willard3 (Mechanical) 18 Mar 18 13:25 Fans in parallel, depending upon the blade type, are difficult to control. This could be the reason for modulating dampers.