Controls And Switches - American Water Heater 300 Series Instruction Manual

CONTROLS AND SWITCHES

This model is provided with two pressure switches. These switches
are essential to the safe and proper operation of the unit. The switches
are wired in series. The controller is set up to shut the unit down
whenever there is a failure of either of the switches. It is important
to understand the purpose of both switches.
50 GALLON UNIT
75 GALLON UNIT
BLOCKED OUTLET SWITCH
The Blocked Exhaust Switch is set up to shut the unit off when a build-
up of positive pressure in the exhaust vent pipe occurs. This switch
is a positive pressure switch that requires an increase in pressure to
change the electrical contacts from normally closed to open. When
this switch prevents the unit from igniting, most likely the exhaust is
blocked by some means. Check to see if the condensate is allowed
to flow freely from the exhaust elbow and for obstructions in the
exhaust venting and exhaust vent terminal. Also verify that the vent
length does not exceed the maximum allowed as shown in the Vent
Section of this manual.
Figure 2
BLOCKED INTAKE SWITCH
The Blocked Intake Switch is set up to shut the unit off when a
build-up of negative pressure in the intake air pipe occurs. This
switch is a negative pressure switch that requires an increase in
negative pressure to change the electrical contacts from normally
closed to open. The switch is connected to the pressure tap on the
PVC pipe connected to the inlet of the blower. When this switch
prevents the unit from igniting, most likely the intake is blocked.
Verify that the screen on the intake air connection (conventional
vent), the intake air pipe and termination (direct vent installations)
are free of obstructions that may prevent air from entering the unit.
Ensure the screen on intake air connection has been removed on
direct vent installations, see Figure 14. Also verify the intake air pipe
length does not exceed the maximum allowed as shown in the Vent
Section of this manual.
WATER HEATING ENABLE/DISABLE SWITCH
IMPORTANT: The Enable/Disable switch listed in this manual is NOT
an "on/off" switch and does not disconnect 120 volt power to the CCB
and other heater components.
Water Heater's Enable/Disable Switch. When in the "Disabled"
position the switch removes electrical power from the gas valve so
that water heating is disabled. The display, CCB, and other electrical
components will still be energized and the display will read "Water
Heating Disabled".
SPARK IGNITER
The Spark Igniter is a device that ignites the main burner by spark.
When high voltage is applied to the igniter, spark is generated to
ignite the main burner.
CONFIGURATION KEY
The configuration key is located inside the control box.
It provides for the ability of the heater to retain information
collected over its lifetime, even if the control board is replaced
because of failure.
The configuration key should stay with the heater.
POWERED ANODE ROD
Some of the models covered in this manual are equipped with a
powered (non-sacrificial) anode rod. Protective current is fed by the
control system to the titanium electrode at the end of the anode rod.
This current flows through the water to the conductive surfaces inside
the storage tank which diminishes the corrosive effect of water when
it comes in contact with steel.
NOTE: To see if a powered anode rod is installed, check the Heater
Status menu of the UIM (user interface module). Refer to Features
and Components (page 10) to locate the UIM. If the water heater is
equipped with a powered anode rod, this menu will display the Anode
Current, Anode Tank Voltage, and Anode Drive Voltage statuses.
See Heater Status Menu (page 45) for more information.
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