State Industries SBD85 500 - Manual (Page 19)

SBD TANK TYPE HEATERS
SERVICE HANDBOOK
Technical Training Department
Ashland City, TN ©2003
18
SBD ELECTRICAL SEQUENCE OF OPERATION
115/60/12A
IID Module
(24V) Receives Voltage
Module (PV) Terminal
Sends 24V to Pilot Coil
Module (Spark) Sends
10,000V Spark to Pilot
Spark Stops
Damper Motor Energized
and Damper Closed
Power to Damper
#2 Interrupted
Themostat Opens
Main Burner Heats Tank
Module (MV)
Terminal Sends 24V
To Main Gas Coil
90 Second Trial /
5 Minute Delay Between
Trials - Continuously
Pilot Ignites and Proves Flame
Cam On Damper Blade
Closes Proving End Switch
Thermostat Closed
High Limit Closed
Tank Temperature
Calling for Heat
Motor Closes
Damper
High Limit (ECO)
Closed
Tank Temperature
Satisfied
24V Transformer
On / OFF Switch "ON"
120 VAC to Junction Box
Motor Opens
Damper