OPERATION
SEQUENCE OF OPERATION
Typical Control/Appliance Operating Sequence
1.When the control is powered, it should display the unit model, water temperature, setting temperature and heater status.
2.If the control determines that the actual water temperature inside the tank is below the programmed temperature setpoint less the differential, a call for heat is activated.
3.The control then performs selected system diagnostic checks. This includes confirming the proper state of the air/gas switches and ECO limit device.
4.If all checks are successfully passed, the combustion blower is energized for the
5.When the
6.At the conclusion of the igniter
7.The igniter will remain on for a short predetermined time period, then will be turned off.
8.The control will monitor the flame sense probe to confirm a flame is present. If a flame is not verified within predetermined time period, the gas valve will immediately be closed, and the blower will continue to run for approximately 30 seconds interpurge. The control will try for ignition two more times before lockout.
9.If a flame is confirmed, the control will enter the heating mode where it will continue heating the tank water until the setpoint temperature plus differential is reached. At this point, the gas valve is closed and the control enters the
10.The combustion blower will run for the duration of the post purge cycle to purge the system of all combustion gases. When the post purge cycle is complete, the blower is
11.The control will now enter the idle state while continuing to monitor the internal tank water temperature and the state of other system devices. If the temperature drops below the setpoint value less differential, the control will automatically return to step 2 and repeat the entire operating cycle.
ELECTRONIC CONTROL
1.Overview
Interaction with the water heater controller is done through an up, a down and three operation buttons. These buttons are shown in the following illustration. Operation of the three lower buttons is defined immediately above them on the screen. The UP and DN buttons are used to navigate through the menus and make adjustments to the water heater.
While the water heater is operating, the user interface will display the desktop screen (if there are no active faults or warnings). An example of this screen is shown in the following illustration. The first temperature on this screen is the temperature of the water
inside the tank. The second temperature on this screen is the Operating Set Point. The Operating Set Point is the temperature at which the water heater will maintain the water inside the tank. The third line on the screen is a text description of the Operational State of the water heater (please see Operating States for more details).
The row of status icons describe graphically operational details of the heater. Following is a legend of all the status icons:
2.Operating States
In the main desktop screen, there are some specific Operating States that are indicated on the status line. These are summerized in the following table:
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