OMM-0153_E
• 5/11/2023 Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST Page 37 of 124
CENTURION Installation, Operation & Maintenance Manual
SECTION 4: START SEQUENCE
Figure 4-5: Air/Fuel Valve in Ignition Position
8. Up to 4 seconds are allowed for ignition to be detected. The ignition circuit is turned off
one second after flame is detected.
9. After 2 seconds of continuous flame, the flame strength is indicated. After 5 seconds, the
Unit Status
screen appears.
10. With the unit firing properly, it will be controlled by the temperature control circuitry. The
unit’s fire rate or valve position (depending on which was chosen in
Main Menu
→
Advanced Setup
→
Unit
→
Front Panel Configuration
) will continuously display on
the Controller’s bar graph.
11.
Once the demand for heat is satisfied the Controller turns off the SSOV gas valve. The
blower relay is deactivated and the Air/Fuel Valve closes.
Standby
is displayed.
NOTE:
Pre-purge default setting is 14 seconds, to provide four (4) air changes of the combustion
chamber, heat exchanger, and exhaust manifold of the unit. This setting can be increased, if
necessary, but should NOT be under 14 seconds, Go to
Main Menu >Advanced Setup >
Performance > Fire Control > Purge Control > Purge Timer.
NOTE:
The purge flow rate is 408 cubic feet per minute.
4.2 Start/Stop Levels
The start and stop levels are the Air/Fuel Valve positions (% open) that start and stop the unit,
based on load. These levels are factory preset and do not normally require adjustment:
Start/Stop Levels
NATURAL GAS
PROPANE
Start Level:
24%
24%
Stop Level:
18%
18%
Ignition Position
35%
35%
Note that energy input of the Water Heater is not linearly related to the Air/Fuel Valve position.
TO BLOWER
AIR IN
IGNITION
VALVE POSITION
DIAL AT
25% to 35%
STEPPER
MOTOR