39
THE DESKTOP SCREEN
During normal operation the control system will display the Desktop
screen on the LCD which is the default screen. The control system
will return to the Desktop screen when there are no active Fault or
Alert conditions or when there has been no user input for several
minutes.
• Manufacturer and water heater model information is displayed
in Title Bar at the top of the Desktop screen. Menu titles are
displayed in the Title Bar when navigating the control system
menus.
• The Operating Set Point is also shown on the Desktop screen.
The Operating Set Point is the temperature at which the control
system will maintain the water inside the storage tank.
• Beneath the Operating Set Point is the Status line. The Status
line shows the current operational state of the control system in
real time. See “Table 13 – Operating States” for a description of
the various operating states.
• The Desktop screen also displays animated Status Icons to
convey operational information, see “Table 12 – Status Icons” for
a complete list and description of the Status Icons.
OVERVIEW
The water heaters covered in this manual are equipped with an
electronic control system that regulates water temperature inside
the storage tank. Heating cycles and ignition are managed by the
control system. The ECO (energy cut out), Flame Sensor, pressure
switches and Temperature Probe is monitored by the control system.
The Combustion Blower, Igniter and the 24 Volt Gas Control Valve
are all energized by the control system.
The main components of the control system are a UIM (user interface
module) and a CCB (central control board). The UIM is located on
the top front side of the water heater. The CCB is mounted on top of
the water heater inside a protective enclosure.
CONTROL SYSTEM NAVIGATION
All operational information and user settings are displayed and
accessed from the UIM. The UIM houses the control system's LCD
(liquid crystal display) and ve snap acting (momentary) user input
buttons; an up, down and three multifunction operational buttons
below the LCD, see Figure 35.
USER INPUT BUTTONS
• The up and down buttons are used to navigate menus and adjust
user settings.
• The operational buttons are used to enter/exit menus, select
menu items, activate adjustment modes and conrm or cancel
new user settings. The operational buttons are multifunctional,
their current function is dened by the text that appears directly
above each button on the LCD screen.

Operating Set Point 120°F

Status: Heating
MENU HELP
GAS
OFF
O
N
MANUFACTURER / MODEL INFORMATION
LCD Screen
Information
Display
Status Icons
3 Operational buttons:
enter/exit menus,
select menu items,
activate adjustment modes,
confirm/cancel changes.
Up & Down buttons:
navigate menus,
adjust user settings
Title Bar
Operational buttons are multifunctional. Their current function is defined by
the text that appears directly above each button on the LCD screen.

UIM (user interface module)

Desktop Screen Shown
UP
DN
Figure: 35
CONTROL SYSTEM OPERATION