Honeywell ST7800A1021 prepurge timer module 10 sec

Honeywell ST7800 A 1021 plug-in purge timer provides the prepurge timing for the 7800 SERIES Relay Module. Prepurge timing: 10 s Verification of safety requirements must be performed EACH TIME the control is installed on a burner to prevent possible hazardous burner operation. Honeywell ST7800A 1021 purge timer installation: Disconnect power to avoid electrical shock and equipment damage. Remove the keyboard display module, dust cover, data bus module, or remote reset module. Pull out the current ST7800A1021 relay module by lifting the plastic support cover. Ensure the new Honeywell ST7800 A 1021 purge timer is set to the desired time period. Insert the purge timer into the relay module slot. Reattach all removed modules and restore power. Run the burner system through a complete cycle to check operation.