Rheem HE119-130LP Use And Care Manual page 12

!
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-
o
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 pre-purge cycle.
4. After the pre-purge cycle is complete, power is applied
to the ignitor element for the ignitor warm-up period
(blower should continue to run).
5. The ignitor warm-up period will last for 30 seconds,
then gas valve will be opened, allowing gas to enter the
burner chamber.
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
post-purge cycle. The flame can be viewed through a
window on the lower right of combustion blower flange.
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 de-energized and will coast to a stop.
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
Pages 16-20 contain nine individual diagrams which illus-
trate the various operating states of the appliance and
their relation to the LED status indicators found on the
controller. These diagrams reflect normal water heater
operation.
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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