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 reenergized 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.