HVAC Procedure and Performance Guide

TASK: Modify existing plenum for evaporator installation.

Training for this procedure can be found in these courses:

                         141 – HVACR Refrigeration l  and  142 – HVACR Refrigeration ll


Plenum must be modified to accommodate specified evaporator according to manufacturer’s specifications. There must be no air leaks or excessive plenum vibration with finished installation. Applicable safety procedures must be followed.


  1. Review job order, manufacturer’s specifications and job specifications.
  2. Collect tools, equipment and materials.
  3. Put on safety and protective equipment and apparel.
  4. Determine dimensions and mounting requirements for the evaporator.
  5. Determine if evaporator has an integral drain pan.
  6. Shut equipment down and turn off electrical power.
  7. Disconnect duct from plenum if necessary.
  8. Remove plenum if necessary.
  9. Cut openings and add flanges in plenum as required.
  10. Install drain pan if applicable.
  11. Provide openings for refrigerant tubing and condensate drain.
  12. Reinstall plenum and connect duct.
  13. Remove safety and protective equipment and apparel.
  14. Gather tools, equipment and leftover materials and leave work site clean.