American Water Heater BCL3 85T390 6NOX - Manual (Page 7)

7
features and Components
Controls
CONTROL BOX ON/OFF SWITCH
VARIABLE
FREQUENCY
DRIVE
DIGITAL
THERMOSTAT
I/O MODULE
LOW SPEED
I/O MODULE
HIGH SPEED
IGNITION
CONTROL BLOWER
PROVER
SWITCH
BLOCKED
INLET SWITCH
BLOCKED
FLUE SWITCH
figure 1.
Variable frequency drive (Vfd)
The VFD controls the speed of the combustion blower. The VFD runs
the blower at low speed during the ignition trial period and adjusts to
high speed after ignition.
i/o module (low and high speed) - the I/O modules switch the
VFD from low speed to high speed blower operation.
Blocked inlet switch - the blocked inlet switch stops burner
operation if the blower air intake becomes blocked.
Blocked flue switch - the blocked flue switch stops burner
operation if the exhaust outlet becomes blocked.
Blower prover switch - the blower prover switch stops the burner
ignition sequence if the blower does not operate.
the eliminator (self-Cleaning system)
These units include The eliminator (Self-Cleaning System) installed
in the front water inlet, see Figure 2. The eliminator inlet tube can
only be used in the front water inlet connection. Do not install the
eliminator inlet tube in either the top or back inlet water connection.
The eliminator must be oriented correctly for proper function. There
is a marked range on the pipe nipple portion of the eliminator, that
must be aligned with the top of the inlet spud. A label above the
jacket hole has an arrow that will point to the marked portion of the
pipe nipple if the orientation is correct. If the arrow does not point
within the marked range on the pipe nipple, adjust the pipe nipple
to correct. A pipe union is supplied with the eliminator to reduce the
probability of misaligning the eliminator accidentally while tightening
the connection to the inlet water supply line. Improper orientation of
the eliminator can cause poor performance of the heater and can
significantly reduce outlet water temperatures during heavy draws.
note: the eliminator may have 1, 3 or 7 cross tubes.
figure 2.
high limit switCh
The digital thermostat (Figure 3) contains the high limit (energy
cutout) switch. The high limit switch interrupts burner gas flow should
the water temperature reach 203°F (95°C).
In the event of high limit switch operation, the water heater cannot be
restarted unless the water temperature is reduced to approximately
120°F (49°C). The high limit reset button on the front of the control
then needs to be depressed.
Continued manual resetting of high limit control, preceded by higher than
usual water temperature is evidence of high limit switch operation.
Contact your dealer or service agent if continued high limit switch
operation occurs.
RESET
BUTTON
LED
LIGHTS
FUSE
140
130
digital thermostat
figure 3.
eleCtroniC ignition Control
each heater is equipped with an ignition control. The solid state
ignition control (Figure 4), ignites the burner by utilizing a spark
igniter. The spark igniter shuts off during the heating cycle and the
burner flame is sensed through a remote flame sensor.
The ignition control will try to ignite the burner three times before
lockout. The control waits 15 minutes before trying again to ignite the
burner. This is a continuous cycle.
ignition Control
figure 4.
Blower/Burner assemBly
figure 5.
spark igniter
The ignition control energizes the Spark Igniter to ignite the burner.
intake air screen
The intake air screen is attached to the inlet end of the combustion
blower. Inspect the intake air screen every six months. The intake air
screen should be cleaned of any buildup of debris or foreign material.
flame sensor
The control system monitors the flame sensor to confirm that flame is
present at the burner. If a flame is not verified during the ignition trial
period (4 seconds) the control system will immediately de-energize
the 24 VAC Gas Valve as indicated on the Sequence of Operation
Flow Chart (Figure 24).