Repair manual

WATER LEVEL CONTROL SYSTEM
TROUBLESHOOTING AND REPAIR
General Description of Operation:
The Cleveland Range water level control, P/N 23198, is designed to maintain operating water
level in Cleveland Range steam generators and to ensure that the heat source is only
operated when the generator water level is above a specified minimum level. The sensing
technique for the control relies on the fact that tap water is conductive to electricity; if
two metal electrodes are immersed in a bath of water, electric current can flow between the
electrodes using the water as a conductor. Water is not a good conductor, like copper, but
is conductive enough to be measured using appropriate electronic circuitry.
The Cleveland Range control is a two probe system having two metallic probes (LOW and HI)
for sensing water in the generator; a COM terminal is placed on the tank. The LOW probe is
placed so that it will come in contact with the water when the water level is just above the
desired water level, enough to protect the heat source. If the water is of sufficient level
and the LOW probe is in the water, a small electrical current provided by the level control
electronics will flow between the probe and COM; this flow will be sensed by the electronics
which in turn will activate the "HEAT" relay to apply AC power to the HEAT terminal on the
control circuit board.
Similarly, the HI probe is located at the desired water level fill (above the LOW probe
level) so that when the water level has reached the desired fill level electrical current
will flow between the HI probe and COM. The action of this probe is reversed from the
previous situation so that when water reaches the HI probe, the WATER fill relay is
deactivated so that AC power to the WF is turned off. When the water level drops below the
HI probe, the WF terminal will be re-energized after a five second delay. The time delay
is to prevent bubbling or turbulence in the generator from chattering to WATER fill relay or
the water valve solenoid.
The control runs on 120 vac and is transformer isolated so that the probes and the
electronics are run at low voltage and are not common to the AC power line.
Note that in many Cleveland Range generators both sensing probes are inserted from the front
top of the unit down into the generator. In this case, the LOW probe will be the longest
and the HI probe will be the shortest.