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This water heater has several lockout features
designed to prevent the heater from operating in
unsafe conditions.
System Status LED Indicator Light
The gas control valve/thermostat (see Figure 1,
item 5) controls and monitors the operation and
safety functions of this water heater. Located on
the front of this control is the ON/OFF switch, the
temperature setting dial and the LED indicator light
(see Figure 47). When energized, this light displays
a sequence of flashes that indicates the operational
status of the water heater. If there is a system
safety shutdown, the LED indicator will present a
flash code to alert the problem. See "System Status
And Error Codes" and "Reading The LED Flash
Sequence".
High Limit Controls (Energy Cut Off)
Thermostat/Water Temperature
This feature is a part of the gas control valve/
thermostat (see Figure 1, item 5) and limits the
maximum water temperature. In the event of the
water overheating, this safety feature shuts off the
fuel supply to the burner.
Blower High Limit Switch
This device (see Figure 4, Item 31)is located on
the blower and limits the maximum temperature of
the blower. If the blower temperature rises above
the temperature setting, the switch opens causing
the heater to shut down. The switch will auto reset
once the temperature drops sufficiently.
Blower Air Pressure Switch
This device (see Figure 4, Item 32), located in the
junction box, monitors the air pressure produced
by the blower. In the event that the exhaust venting
becomes blocked or sufficiently restricted, the
switch will shut the heater down.
Flammable Vapor Sensor
When using a gas fired water heater there is a
risk of flammable vapors entering the combustion
chamber, being ignited by the burner flame and
causing a flashback. In order to detect such
flammable vapors before they enter the combustion
chamber, this water heater is equipped with a
flammable vapor sensor (FVS). It is a chemical-
absorption based sensor that is connected to the
gas control/thermostat (see Figure 45). When
exposed to flammable vapors it will trigger the
control to stop the flow of gas and enter the FVS
lockout state. While in the FVS lockout state the
LED on the control will flash the gas lockout code.
(Refer to the "System Status And Error Codes"
section of this manual for an explanation of the
codes applicable to the control installed on your
water heater.) If this error occurs, check around the
water heater for sources of chemical contamination
such as: flammable vapors including gas vapors,
solvents, paint and thinners as well as sources of
water and detergents.
NOTE: Resetting the heater will reset the FVIR
circuit if all sources of contamination have been
removed and the sensor clears. If all sources of
contamination have been removed and the system
will not reset, the sensor will need to be replaced
(see "Resetting the Heater Control").
If there is a problem with the wiring of the
flammable vapor sensor or the flammable vapor
interface, the LED will flash the failure status code
(see "System Status And Error Codes").
* ROTATE LEFT (CCW) TO
REMOVE
COVER*
MOU# NG
BRACKET
FLAMMABLE VAPOR
SENSOR (PULL TO
REMOVE)
Figure 45
44
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