HVAC Procedure and Performance Guide

TASK: Install humidifier: Bypass Type

Training for this procedure can be found in these courses:

                         205 – High Efficiency Ventilation   and   241 – Intro to Cooling Systems


Bypass humidifier must be installed according to manufacturer’s specifications and job specifications.  Unit must operate quietly and must respond to control signal.  It must not leak or overflow.  Applicable safety procedures must be followed.


  1. Review job order, manufacturer’s specifications and job specifications.
  2. Determine work site location.
  3. Collect tools, equipment and materials.
  4. Put on safety and protective equipment and apparel.
  5. Prepare openings in hot-air plenum or supply duct and cold-air plenum or return duct.
  6. Mount humidifier according to manufacturer’s specifications (on plenum or duct or adjacent to equipment).
  7. Connect inlet side of humidifier to return air system.
  8. Connect discharge side of humidifier to hot-air plenum or duct wherever applicable.
  9. Make electrical connections if applicable.
  10. Connect low-voltage wires from humidistat if applicable.
  11. Make water supply connection to water inlet.
  12. Install overflow and drain with trap.
  13. Inspect installation and media element. 
  14. Start unit and check operation.
    1. Adjust water level or flow control.
    2. Ensure response to humidistat’s signal.
    3. Ensure correct operation according to manufacturer’s specifications.
  15. If equipment does not operate to specifications, troubleshoot and make required adjustments and repairs.
  16. Make final inspection of work.
  17. Leave equipment in required operating status.
  18. Remove safety and protective equipment and apparel.
  19. Gather tools, equipment and leftover materials, and leave work site clean.