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!DANGER
There is a hot water SCALD POTENTIAL if the thermostat is set too high.
THERMOSTAT DIFFERENTIAL ADJUSTMENT PROCEDURE
To allow proper water heater operation, the control has an 8°F "window" around the set point. This means that the burner will be turned on when the water temperature drops to 4°F below the set point, and it will be turned off when the water temperature reaches 4°F above the set point. Thus, if the set point is set to 120°F., the control will turn on the burner when the water temperature drops to 116°F., and will continue to heat the water until the temperature reaches 124°F. The differential is factory set to 8°F (+ or- 4°F.) If another differential is required, the value of the differential can be field adjusted by holding the set point button when power is applied to the control. Shut off power to the control. Next hold in the set point button. Now reapply power to the control. Using the set point button, the value of the differential can be incre- mented or decremented as above. When the proper value is reached, release the button and wait for the dis- play to show "00". This indicates the new differential has been stored into permanent memory. Remove power and restart control by applying power for normal opera- tion.
OVERALL APPLIANCE AND CONTROL OPERATION
A normal operating sequence is as follows:
1.The control determines that the actual water tempera- ture inside the tank is 4 degrees F below the pro- grammed temperature set point.
2.The control performs selected system diagnostic checks.
3.If all checks are successfully passed, the combustion blower is energized for the 40 second
4.After the
5.The ignitor
6.The ignitor will remain on for an additional 4 seconds, then it will be turned off.
7.After an additional 2 seconds, the control will verify the presence of flame. If the flame was not established, the gas valve will be closed, power will be removed from the ignitor element, and the control will run the blower for 30 seconds. This removes excess fuel from the combustion chamber. At this point, the control will return to step 2.
8.If flame is present, the control will enter the heating mode where it will continue heating the tank water until the set point temperature plus 4°F is reached. At this point, the gas valve is closed and the control enters the
9.The post purge cycle continues to run the combustion blower for an additional 30 seconds to purge the system of all combustion gases. After this time period, the blow- er is
10.The control will now enter the idle state while contin- uing to monitor internal tank water temperature. If the temperature drops to 4°F below the set point value, the control will automatically return to step 1.
STATUS INDICATORS
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MAINTENANCE
!CAUTION
In unusually dirty or dusty conditions, care must be taken to keep appliance door in place. Failure to do so VOIDS WARRANTY!
The control system requires no periodic maintenance under normal conditions. However, in unusually dirty or dusty conditions, periodic vacuuming of the cover to maintain visibility of the display and indicators is recom- mended.
INTERNAL WIRING
For specific wiring information, please refer to the dia- grams on pages 21 and 22.
SHUTDOWN PROCEDURE
If the burner is operating, lower the set point value to 70°F and wait for the burner to shut off. Continue to wait for the combustion blower to stop so all latent combustion gases are purged from the system. This should take a maximum of 40 to 90 seconds. Disconnect the electrical supply. If the burner is not oper- ating, disconnect the electrical supply.
VACATION PROCEDURE
If there is danger of freezing, change the set point to 70°F. DO NOT turn off electrical power. If there is no danger of freezing, follow the "Shutdown Procedure".
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