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LOW GAS PRESSURE SWITCH
The Low Gas Pressure Switch is a single pole, normally open
pressure switch that will close its contacts when a rising pressure
of 6.2 inches (1.53 kPa) w.c. is encountered. The contacts will
open when the pressure falls below the fixed set point of 6.2 inches
of w.c. The Low Gas Pressure Switch monitors the gas supply
pressure to the heater. If the gas supply falls below the 6.2 inches
of w.c., the main burner is extinguished (if heater is running) or the
heater will not start up, see Figure 15.
ON/OFF SWITCH
The ON/OFF Switch is a single pole, single throw rocker switch.
This switch provides 120V from the electrical source to the heater,
see Figure 16.
HOT SURFACE IGNITER
The Hot Surface Igniter is a device that ignites the main burner by
high temperature (1800°F). When the 120 VAC is applied to the
igniter, sufficient heat is generated to ignite the main burner.
Although improvements have been made to strengthen the igniter,
it is still fragile and care must be taken when handling the igniter to
prevent breakage, see Figure 17.
FIGURE 15
FIGURE 16
FIGURE 17
OIM - OUTDOOR INTERFACE MODULE
The OIM is a device that monitors the control system. It monitors
the ignition control assembly, the tank and outlet temperatures,
the low water cutoff device, and the pressure switches. The display
board provides operating information. It records and logs error
messages for diagnostics. The module is equipped with a touch
pad for easy access to observe menus and current status of
control, see Figure 18.
WR IGNITION CONTROL BOARD
The WR Ignition Control Board performs the ignition sequence for
the water heater. It controls the diagnostics of the system and
monitors all the pressure switches, the flame sensing device, the
thermostats, the E.C.O., and components that make up the control
system. The difference between the WR Ignition Control Board is
that the OIM board monitors all the controls and provides that
information through the LCD display where the WR Ignition Control
Board provides the means to control the complete sequence of
operation and switches, see Figure 19.
9
FIGURE 18
FIGURE 19
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