American Water Heater BCL3 85T390 6NOX, BCL3 95T199 6NOX Features and Components, Controls

Controls

Features and Components

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CONTROL BOX	ON/OFF SWITCH	140

RESET BUTTON

VARIABLE

FREQUENCY

DRIVE

DIGITAL

THERMOSTAT

I/O MODULE

LOW SPEED

I/O MODULE

HIGH SPEED

BLOCKED INLET SWITCH

BLOCKED FLUE SWITCH

IGNITION

BLOWERCONTROL

PROVER

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.

LED	FUSE
LIGHTS

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.

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.

IGNITION CONTROL

Figure 4.

Blower/Burner Assembly

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.

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).

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