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Local water conditions may cause excessive boiler
scale build-up and cause the generator and
compartment controls not to work. Proper periodic
service must be performed as outlined in the operating
and service instructions. It may also be necessary to
install a water conditioner on the generator water
feed. Contact your local water conditioner dealer.
Inspect and Clean Inside of Generator Shell
Flush (blow down) steam generator. Drain water from
the shell with the electric power OFF (no heat on).
Hold the pressure relief valve open to allow air to
enter for better drainage.
Remove generator hand hole cover (top front of shell)
by removing the nut and clamp, then tapping the
cover lightly to free it while holding the cover stud (this
prevents cover from dropping into generator). When
replacing cover, clean gasket seating surfaces.
Always use a new cover gasket.
Use wire brushes to free the scale. Loose material
must be either scooped from the steam generator or
flushed through the drain.
A suitable agent for removing lime may be used to
remove scale build-up, but use caution to avoid
damage to brass and copper parts of generator
controls, etc.
If a solvent is used, it is recommended that the
generator be removed (see REMOVING
GENERATOR ASSEMBLY), the descaler, sensing
probes and heating elements or steam coils, if
furnished, be removed, and that the shell be stood on
its end and filled with the solvent. One solvent
commonly used for removing lime is muriatic
(hydrochloric) acid (two parts of commercial muriatic
acid to 14 parts of cold water should be strong
enough). A heavily scaled shell may require a soaking
period of several hours.
When using these solvents, carefully read and follow
the instructions provided with the product. Perform
work in a well ventilated area.
Drain completely and thoroughly flush shell with fresh
water, repeating several times to be sure all traces of
the lime removing agent are flushed away.
Descaler
The descaler is accessible through the hand hole
opening. It is a coiled wire wound around a solid
cylindrical core, and hangs by an open loop from the
shell’s horizontal stay rod, about 4" from the front of
the shell. If the wire is eaten through, or if the core of
the descaler is eaten away to half its original size, a
new descaler should be installed. To install a new
descaler, stretch its wire coil so that the descaler
hangs with its core completely below the minimum
water level in the generator, but hanging free. The
descaler must not contact the bottom of the generator
shell, or the electric heating elements or regenerator
steam coils (if applicable).
Low Water Cutoff/Automatic Fill Control
The steam generator is equipped with level sensing
probes and relays for controlling the flow of feed
water to the boiler and to turn off the heat source when
the level is too low.
The low level control is a simple series circuit with a
transformer, secondary coil, relay coil, electrode,
metal boiler and water. When water is below the low
level cutoff electrode probe, the circuit is open and the
coil is deactivated. When the water level is at or
above the electrode probe, the circuit is closed by a
path through the liquid from the probe to the metal
boiler. The relay coil and the n.o. relay contacts 7 &
8 transfer positions, activating the heating contactor,
or combination control, or solenoid valve.
The differential level control relay coil activates and
the n.c. contacts 3 & 4 transfer positions once the
water level reaches the top probe.
The relay coil will deactivate when the water level
goes below the low level probe. This is achieved by
holding the circuit closed with the use of an additional
lower electrode probe through the n.o. contacts 7 & 8
on the relay. The relay activates when the water level
reaches the top high level electrode probe, but does
not deactivate until the level recedes below the low
level electrode probe.
Loose electrical connections may prevent the heat
from coming on or may cause the boiler to overfill.
Accumulation of boiler scale on or near the sensing
probes may cause them to retain water on the insulator
surface. This may prevent the boiler from filling or
cause dry firing. DRY FIRING WILL RESULT IN
DAMAGE TO HEATING ELEMENTS OR TO THE
BOILER SHELL.
