A.O. Smith BTH 120 Service Handbook page 11

7. Record the supply gas pressure.
8. Use the Enable/Disable Switch located on the front of the water heater and put the unit in enabled mode.
The settings on the water heater may need to be changed to cause the water heater to operate. Note the
Operating Temperature Set Point so that the unit can be returned to this setting at the conclusion of this
test procedure. Increase the Operating Set Point if necessary to cause the water heater to have a call
for heat.
9. Record the supply gas pressure when the Ignition Activation operating state begins; when the animated
Gas Control valve Status Icon appears on the UIM Screen.
• The supply gas pressure will typically drop as the Gas Control Valve opens.
Putting The Water Heater Back In Service
10. Lower the Operating Set Point to end the heating cycle. Use the Enable/Disable Switch located on the
front of the water heater and put the unit in disabled mode.
11. Close the main gas shutoff valve serving the water heater.
12. Disconnect manometer sensing tube.
13. Close the Supply Gas Pressure Test Port on the Gas Control Valve. Turn the needle valve slotted head
clockwise until tight.
14. Open the main gas shutoff valve serving the water heater and check for leaks at the Gas Control Valve
test ports.
15. Use the Enable/Disable Switch located on the front of the water heater and put the unit in enabled mode.
Increase the Operating Set Point if necessary to cause the water heater to have a call for heat.
16. Run the water heater through a complete heating cycle before leaving to ensure it is operating properly.
Return the Operating Set Point Temperature to its original setting. Draw water from the nearest faucet to
make sure that the water temperature does not pose a scalding hazard due to the increased temperature
set points that were used in this procedure.
10 Servicing should only be performed by a Qualified Service Technician