John Wood Commercial - 300-400K BTU - Manual (Page 43)

43
operating states
The current operational state of the water heater is displayed on the Desktop screen as the "Status." The common operational states
are described in the table below. See Figure 55 on page 41 and the Sequence Of Operation on page 54.
table 11
state description
Standby The water heater is not in an active heating cycle. IE: the Tank Temperature is at or above the Operating Set Point.
Input Verification The control system is conducting a diagnostic check at the beginning of a heating cycle.
Short Cycle Delay The control system is waiting for a pre-defined time period to expire before initiating a heating cycle. This prevents "short-
cycling" which can greatly accelerate wear on components such as the Hot Surface Igniter and Combustion blower.
note:
If the control system is in this operational state increase the Differential setting in the Temperatures menu to lengthen
heating cycles.
Pre-Purge
The Combustion blower is energized to flush residual flue gases from the combustion chamber prior to ignition.
Igniter Warm up The Hot Surface Igniter is energized and is currently warming up to ensure proper ignition.
See the Sequence Of Operation on page 44 for minimum current (AC amps) information.
Ignition Activation The 24 VAC gas Valve is energized and opens to allow fuel gas to flow to the Main burner.
Ignition Verification The control system is monitoring the flame sensor for the required minimum flame sensing current.
See the Sequence Of Operation on page 44 for minimum flame sensing current (DC micro amps) information.
Inter-Purge The Combustion blower is energized to flush residual fuel gas from the combustion chamber after a failed ignition attempt.
Heating
Ignition was successful, flame sensing current has been established. The water in the storage tank is being heated.
Post-Purge The Combustion blower is energized to flush residual flue gases from the combustion chamber at the end of a heating cycle.
Fault
The control system has detected a Fault condition. Heating operation is disabled until the Fault condition is corrected. Power
to the water heater must be cycled off and on to reset the control system.
note:
Cycling power will not reset the control system if the condition that caused the Fault has not been corrected.
control system menus
From the Desktop screen pressing the Operational directly below "Menu" on the LCD will display the "Main Menu" this is where all
control system menus are located. The table below describes the control system menus.
table 12
menu description
Temperatures Most commonly accessed menu. Contains the Operating Set Point and Differential user settings.
Heater Status
This menus displays the current state of all pressure switches and the ECO (open/closed). The on/off status of the
Combustion blower, gas valve, igniter, flame sensor and other monitored water heater components are displayed in
this menu.
Display Settings Temperature units (°F or °C), the LCD appearance (brightness/contrast) and backlight delay user adjustable settings
are located in this menu.
Heater Information Elapsed time of operation, total heating cycle time, heating cycle count, heating on time along with uIM and CCb
software revisions can be viewed in this menu.
Current Fault Displays any current Alert or Fault messages.
Fault History
This control system menu retains a list of the last nine (9) Fault and Alert messages with a time stamp. The newest
event will replace the oldest.
Fault Occurrence This control system menu retains a running total of how many times each Fault condition has occurred since the water
heater was first installed.
restore Factory Defaults This control system feature allows the user to restore control system user settings to their factory default settings.
Display Settings preferences ArE NOT changed when factory defaults are restored.
Help Screens Text based operational and user information explaining how to change user settings, navigate the control system menus
and icon descriptions.