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References: Rotation and Discharge Codes

  1. Clockwise - Wikipedia - Defines clockwise and counterclockwise rotation and shows that the direction reverses when viewed from the other side, the idea behind every CW and CCW code in this chapter.

  2. Axial fan design - Wikipedia - Explains how axial fan blades, hubs and rotation produce flow along the axis. Background for the chapter's axial rotation convention and the LH and RH designations viewed from the discharge side.

  3. Three-phase electric power - Wikipedia - Explains three-phase supply and states that interchanging any two phases reverses a three-phase motor, the fix used in the chapter's startup bump check.

  4. Fan Handbook: Selection, Application, and Design (1998) - Frank P. Bleier - McGraw-Hill - Written from the viewpoint of a working fan application engineer, Bleier's handbook treats fans as equipment to be specified and installed, the setting in which rotation, discharge and motor position codes matter.

  5. ASHRAE Handbook - HVAC Systems and Equipment - ASHRAE - The fans chapter of this standard HVAC reference covers fan types, installation and system connections, giving context for why outlet direction and motor location must be fixed on the order.

  6. FanPedia: The Fan & Blower Encyclopedia (PDF) - Twin City Fan - The chapter's primary source: axial rotation (pp. 37-42), discharge codes (pp. 46-49), configurations (pp. 50-51), motor and conduit box positions (pp. 52-57, 75) and restrictions (pp. 162-166).

  7. FanPedia online - Twin City Fan - Online edition of FanPedia; its Discharges & Impeller Rotation, Impeller Airflow & Rotation (Axial Fans) and Motor Positions galleries show the CW, CCW, DWDI and plenum drawings behind this chapter's codes.

  8. ANSI/AMCA Standard 99-16, Standards Handbook (PDF) - AMCA International - Section 11 sets the designation of rotation and discharge from the drive side, with the discharge angle measured in the direction of rotation, the basis of the angle form of the code.

  9. Fan Arrangements, Rotation, Discharge and Motor Position (FE-3900) - Twin City Fan - Engineering letter reproducing AMCA's rotation and discharge and motor position drawings. Handy to keep beside the order form when writing the codes this chapter teaches.

  10. Product Catalogs - Twin City Fan - Current Twin City Fan product catalogs. The chapter tells you to check the current catalog before promising a discharge, such as a DWDI fan blowing bottom angular down, that FanPedia does not list.