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The contactor block is the terminal block to which the element leads are connected and where
actual contact is made between the leads and the line voltage. Built into the contactor block is a coil
(electronic switch) that closes when a ground for the 24VAC from the transformer is supplied by the
controller calling for heat. When it closes, contact is made between the incoming line voltage and
the element leads.
The element is a resistive heating device. That is, when voltage is applied to the element, the
element gets very hot due to its resistance to current flow through it. The heat generated is
transferred directly to the water in which the element is immersed.
The controller is the interface between the operator and the other components of the equipment. In
the water heating system, its function is to control the application of line voltage to the heating
element via the contactor coil.
Troubleshooting the water heating system consists of checking the above components for proper
operation, as detailed in the troubleshooting diagrams on the next page.
6.4.3 Technician Troubleshooting Guides
TROUBLESHOOTING
THE AUTOFILL
SYSTEM
What is the
problem?
Solenoid valve
does not close
when water
reaches upper
water level sensor.
Solenoid valve
does not open
when water is
below upper water
level sensor.
Is 24VAC
present at pin 6
of the 15-pin
plug?
Is 24VAC
present at pin 6
of the 15-pin
plug?
Check for shorting
of sensor to ground. If
sensor is not shorted,
computer has failed.
Replace.
Problem resolved.
Valve has failed.
Replace.
Clean sensor with
a scouring pad.
No
Add 1/8 cup
baking soda to
water and stir.
Is AutoFill
functioning
properly?
No
Yes
Yes
Is AutoFill
functioning
properly?
Substitute a
controller known to
be working for
suspect controller.
No
YesNo
Is AutoFill
functioning
properly?
Yes
Probable cause is
loose/broken wiring
or damaged sensor.
No
Problem resolved. Yes
Computer has
failed. Replace.