20X8 PRD | 20X8 Rectangular Manual Bypass Damper | EWC Controls

20X8 Rectangular Manual Bypass Damper

GENERAL DESCRIPTION

The model PRD Pressure Regulating Bypass Dampers are a single blade rectangular barometric damper assembly with a counter balanced weighted arm. The barometric bypass damper is an economical way to manage the duct static pressure when zone dampers close. Bypass Damper adjustment is achieved by off-setting the hex shaped arm, securing weight #1 towards the bottom of that arm and moving the extra weight(s) (optional) up or down the arm, until the desired action is achieved. Additional weights can be added if necessary. See Page 3 for details. The damper can be mounted to relieve static pressure by returning the air back to the return air duct or by dumping it into a non-critical conditioned area. A restricting hand damper (part# ND-HD) should be installed downstream of the PRD by-pass damper, which allows the installer to set the desired pressure drop across the bypass duct, thereby controlling how much by-pass air mixes with the return air. See Application Note 090376A0169 rev F. Together, the PRD and ND-HD are an effective low cost bypass solution, for any residential zoned HVAC system.