A.O. Smith dre-120 Installation And User Instructions Manual - page 8
8
1.2.2 Checking the Float Switch
Switch off the feed voltage and remove
the fuses from the elements. In this
way the control circuit can be tested
without the elements being put into
operation. Drain the device until the
water is definitely below the float switch.
If desired the float switch can now be
removed for visual inspection. Check
the resistance of the contacts with a
multimeter and check whether the switch
point is situated approximately halfway
along the stroke of the float. (For new
contacts this resistance is between 1
and 1.5 Ohms). Screw the float switch
back into the tank and place it vertically.
Check the exposure height. Close the
door and connect the feed voltage. The
safety relays must not come in. (The
tautening and release of the safety
relays is clearly audible.) Now allow
water to flow into the device. If the water
presses the float upwards, the float
switch closes the control circuit and the
safety relays will tauten. Then drain the
device once again. The lowering of the
water level will lead to the float switch
blocking the control circuit once again
and the safety relays will release. Repeat
this operation at least one time.
Switch off the feed voltage and fit the
fuses of the elements again. Close the
door and reconnect the feed voltage.