3033-005B Section 5: Plumbing
Concordia Xpress Technical Support Manual 5-5
2900-300B
Temperature/Level Probe
The temperature probe and level probe are combined into a single unit.
Level Probe
The CPU uses the level probe to verify the presence of water in the tank.
To verify the presence of water, a pulsed 300mv signal is sent to the
probe. The presence of water in the tank will cause the signal to shunt to
ground. When the signal is grounded the CPU knows the tank has water
and this allows the CPU to activate the heater (if needed).
If the signal is not shunted to ground, the CPU cannot activate the
heater. If the level probe fails to detect water in the tank for a period of
60 seconds or more, the message CHK WATER SUPPLY is displayed.
For information on troubleshooting the CHK WATER SUPPLY message,
please see Section 15: Troubleshooting.
If the water level in the tank is low and the circuit is open, the CPU
activates the brew water valve, allowing line pressure to fill the tank.
When the signal from the
probe finds ground, the
CPU assumes water is
present in the tank.
Water Tank and Level Probe Grounded
When the circuit is open
and the CPU detects low
water, the brew water valve
opens and allows water into
the tank.
The heating elements are
then inhibited.
Water Tank and Level Probe Not Grounded
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