HVAC Procedure and Performance Guide

Adjust fan speed for correct CFM output

Training for this procedure can be found in these courses:

                         131 – Oil Heat l  and  161 – Boilers l


Fan must deliver specified CFM air-flow.   Speed must be adjusted by reconnecting multi-speed motor, adjusting variable belt sheaves, or changing belt sheaves.  Applicable safety procedures must be followed.


      1. Review manufacturer’s specifications and job specifications.
      2. Determine required air-flow and available adjustment options.
      3. Collect tools, equipment and materials.
      4. Put on safety and protective equipment and apparel.
      5. Measure air-flow and compare duct air-flow measurements to specifications.  (Note:  Ensure that duct is not blocked by closed dampers or other obstructions and that filters are clean).
      6. Remove safety guard(s) and access cover(s).
      7. Adjust fan speed to obtain desired flow.
      8. Reconnect multi-speed motor to higher or lower speed as required.
      9. Adjust variable belt sheaves for higher or lower fan speed as required, and reset belt tension.
      10. Change belt sheaves and belt if necessary.
      11. Re-measure air-flow and verify that air-flow is within specifications.
      12. Check motor amperage and verify that motor is not overloaded.  (Note:  If overload condition exists, install larger motor).
      13. Replace safety guard(s) and access cover(s).
      14. Leave equipment in required operating status.
      15. Remove safety and protective equipment and apparel.
      16. Gather tools, equipment and leftover materials, and leave work site clean.