A.O. Smith 100 Power Vent DV Series 120, 317443-000 Control system operation, Overview

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 Probe is monitored by the control system. The Combustion Blower, Igniter and the 24 Volt Gas 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.

Commercial And Residential Models

The water heaters covered by this manual are produced for commercial and residential use. The control system is programmed differently for commercial and residential models. There are two differences in control system operation between the residential and commercial products:

•Commercial models will display Tank Temperature on the Desktop screen, residential models will not.

•Commercial models can regulate tank temperature up to a maximum of 180°F (82°C), residential maximum is 160°F (71°C).

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 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 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 - commercial models only.

•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 4 for a description of the various operating states.

•The Desktop screen also displays animated "Status Icons" to convey operational information, see Table 3 for a complete list and description of the Status Icons.

UIM (user interface module)

Desktop Screen Shown

LCD Screen	MANUFACTURER / MODEL INFORMATION
Information	Operating Set Point	120°F
Display
	Status: Heating
Status Icons	OFF
	GAS	O
		N

MENUHELP

Title Bar

UP

DN	Up & Down buttons:
	navigate menus,
	adjust user settings

Operational buttons are multifunctional. 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 35.

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