A.O. Smith CAWH 8-455-12, Installation, User And Service Manual

Page: 38 / 304

6.3 Safety devices
Fig. Safety thermostat
1. Heating element
2. Safety thermostat -
body
Safety devices of the water heater:
Safety thermostats There is a surface-mounted ECO (Energy Cut Out)
control installed for each installed heating element.
The ECO high temperature limit switch contacts on
each control will open when the tank temperature
reaches approximately 93°C. When the upper ele-
ment ECO switch contacts open (activate), voltage
to the main control board (CCB) and user interface
module (UIM) is terminated to prevent further
heating operation. Voltage will still be present to
the water heater, however the UIM on the front of
the heater will be blank.
The lower element ECO switch contacts open (acti-
vate) voltage to the lower element only is termina-
ted to prevent further heating operation in the bot-
tom of the tank. The upper element will continue to
operate to heat water.
The surface-mounted ECO is a manual reset
switch. If one or more ECO's activate, the tank
temperature must drop below 60°C and electrical
power disconnected and restored before an ECO
can be reset. To manually reset an ECO, do the fol-
lowing:
. Disconnect the power supply to the water
heater.
. Allow the tank temperature to cool below
60°C.
. Remove the control cover from the effected
control(s).
. Press the manual reset button on each of the
effected controls.
36 Installation, Maintenance and Service part
EN