Control System Operation
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 probes are monitored by the control system. The Combustion Blower, igniter, 24 VAC Gas Valve and anode rods are all powered 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. See Features And Components on page 7 for location of these and all water heater components.
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 five snap acting (momentary) user input buttons; an up, down and three (3) multi functional operational buttons below the LCD, see Figure 55.
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 confirm or cancel new user settings. The operational buttons are
multifunctional, their current function is defined by the text that appears directly above each button on the LCD screen.
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 first temperature shown on the Desktop screen, Tank Temperature, is the temperature of the water inside the water heater's storage tank.
•The second temperature shown on the Desktop screen is the Operating Set Point. 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 12 on page 44 for a description of the various operational states.
•The Desktop screen also displays animated "Status Icons" to convey operational information, see Table 11 on page 43 for descriptions of the Status Icons.
UIM (user interface module)
LCD Screen
Information
Display
Status Icons
Desktop Screen Shown
MANUFACTURER / MODEL INFORMATION
Tank Temperature | 103°F |
Operating Set Point | 120°F |
Status: Heating |
|
OFF |
|
GAS | O |
N | |
MENU | HELP |
Title Bar
UP
DN | Up & Down buttons: |
| navigate menus, |
| adjust user settings |
Operational buttons are multi functional. Their current function is defined by the text that appears directly above each button on the LCD screen.
3 Operational buttons: enter/exit menus, select menu items, activate adjustment modes, confirm/cancel changes.
Figure 55
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