SBD TANK TYPE HEATERS
SERVICE HANDBOOK
SBD SEQUENCE OF OPERATION
1.Thermostat calls for heat
7.Thermostat satisfies 
3.Intermittent Ignition Control
5.Main gas valve opens 
SEQUENCE OF OPERATION
9.Flue damper closes
2.Flue damper opens
4.Pilot gas opens, Pilot sparks and flame proves
6.Main burner ignites
8.Main and pilot burners "OFF"
To understand SBD tank type water heaters, an examination of their sequence of operation is necessary.
When the thermostat calls for heat, the relay in the draft hood assembly activates the flue damper motor. The damper opens and power flows to the IID (Intermittent Ignition Device). This activates the IID module to open the pilot valve and begin sparking at the pilot burner assembly. Once the pilot flame is established and confirmed back to the IID, the sparking is stopped and the main gas valve is opened, allowing gas flow to the main burner. When the thermostat satisfies, main and pilot gas is shut off. Damper is returned to closed position.
Technical Training Department | 16 |
Ashland City, TN ©2003 |
