Service; Warranty; Principles Of Operation - Fetco CBS-31A User Manual

Service

Warranty

All FETCO brewers come with a limited warranty. All warranty service must be pre-authorized by calling the
FETCO Service Department at (800) 338-2699.

Principles of Operation

Fill System
The fill system consists of a liquid level control board, a water level probe at the top of the tank, and a fill valve. As
the water rises and touches the probe, continuity is established between the probe tip and the tank body, and the
fill valve closes.
When water is dispensed, the water level drops below the probe. After a 5 second delay, the fill valve opens until
the water touches the probe again. The 5 second delay, and the speed that water refills the tank during brewing,
results in many short bursts of water. The sound made by these repetitive bursts will let you know the fill system is
functioning normally. (This sound may not be audible in a noisy environment.)
The fill system is designed to protect the heaters during both the installation and a loss of the water supply. During
initial installation, or whenever the power switch is turned on, voltage will not be supplied to the thermostat until the
tank fills and water touches the water level probe. During operation, when water is dispensed and the water level
drops below the probe, a fill signal is sent to the fill valve. If no water is sensed by the probe after 40 seconds, the
voltage to the thermostat and the heaters is removed.
Water enters the tank near the bottom. This introduces cold incoming water directly to the heaters and away from
the dispense assembly.
The water tank can be drained through a valve located on the back of the brewer, near the incoming water
connection.
Temperature System:
The temperature system consists of an electronic thermostat, a temperature probe, and heating elements, and is
enabled by the liquid level control board. (See the previous section - Fill System.)
When the water level probe is in contact with water, power is delivered to the thermostat through the liquid level
control board. If the temperature probe senses that the water is not hot enough, the thermostat energizes the
heating elements through the mercury relay, the water is heated, and the ready light goes off.
Once the water temperature reaches the set point, the thermostat disengages power to the heaters and the ready
light illuminates. The thermostat is adjusted to 203° F ± 2° at the factory. (Slightly lower for high altitude
installations.)
Timing & Dispense System:
The timing system consist of the timer, the dispense valve, the brew start switch, and the brew stop switch. When
the brew start switch is pressed, the timer starts its' cycle. The timer energizes the dispense valve, which opens
and allows water to flow into the brew basket. It also lights the brew light. The valve remains energized throughout
the brew cycle timed sequence.
When the timer finishes its cycle, it removes voltage from the dispense valve. The valve closes, the flow of water
stops, and the brew light goes out.
The brew stop switch is used only when it is necessary to interrupt the brew cycle before the cycle is finished.
The timer used with the half batch option has a small jumper wire on one end. A switch can replace this jumper to
open or close this connection. Opening this connection cuts the timed output in half.
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