HVAC Procedure and Performance Guide

Replace potential relay

Training for this procedure can be found in these courses:

                         131 – Oil Heat l  and  161 – Boilers l


Potential relay must be installed according to manufacturer’s specifications.  Relay must be correct rating for equipment.  Applicable safety procedures must be followed.


  1. Review job order and manufacturer’s specifications.
  2. Determine relay requirements.
  3. Coil voltage.
  4. Pickup voltage.
  5. Dropout voltage.
  6. Required contact action.
  7. Collect tools, equipment and materials.
  8. Put on safety and protective equipment and apparel.
  9. Locate relay to be replaced.
  10. Disconnect electrical power to system.
  11. Remove safety guard(s) and access cover(s).
  12. Remove old relay.
  13. Verify that new relay is a suitable replacement.
  14. Mount and connect new relay according to manufacturer’s instructions.
  15. Test motor operation and determine if relay is providing required performance.
  16. If equipment does not operate to specifications, troubleshoot and make required adjustments and repairs.
  17. Stop equipment and replace safety guard(s) and access cover(s).
  18. Leave equipment in required operating status.
  19. Remove safety and protective equipment and apparel.
  20. Gather tools, equipment and leftover materials and leave work site clean.