40
TROUBLE SHOOTING - SYMPTOM, CAUSE AND ACTION
(Continued)
SYMPTOM
CAUSE
ACTION
Arching in the steam
cylinder
An occasional arc is not a problem. When
a cylinder is restarted after a long period of
off time arcing may occur as pieces of mineral
flake off the electrode surface. During a drain
cycle, arcing may occur if water is very low in
the cylinder. Arcing is a problem if it occurs
frequently or if it causes dark brown or
red discoloration in the cylinder. The dark
deposits are caused by deterioration of electrode
material and must be prevented. Arcing may be
caused by several conditions:
Incoming water may have high conductivity.
Conductivity, the ability to conduct current, is
measured in “micromhos”. In any electrode
type humidifier there are maximum values of
conductivity that may be used in the humidifier. It
is very unusual for any naturally occurring water
to have conductivity that is too high for operation.
It is recommended that water conductivity be
less than 900 micromhos. If water is treated by a
water softener its conductivity will be higher than
untreated water. As it is boiled away its
conductivity also increases at a higher rate than
untreated water. Softened water may be too high
in conductivity to operate without arcing.
Drain lines within the humidifier that have become
restricted by mineral deposits prevent proper drain
rates. This causes minerals to concentrate inside
the cylinder, which in turn causes low water levels.
Low water levels cause arcing. Drain lines should
be inspected when cylinders are changed and
thoroughly cleaned if necessary.
A defective drain solenoid valve will prevent proper
draining. The solenoid should be checked to verify
that it moves freely when 24VDC is applied to the
coil. When placed in the “Drain” position, both the
drain and fill valves open and it is very important
the water level falls in the cylinder.
Insufficient flow of incoming fresh water will cause
arcing by causing low water levels. Since an
automatic drain is not initiated until setpoint is
reached, a drain will not occur if the flow rate is
too low. Therefore, if low water pressure at the
humidifier (below 20 psi) or a clogged water
strainer restricts the flow of water, arcing will result.
High back pressure, which can be caused by an
obstruction in the steam hose, prevents fresh
water from entering the cylinder and results in
arcing. Care must be taken to prevent kinking of
steam hose when making bends.
Excessive lengths of steam hose in conjunction
with high duct static pressures cause low water
levels and arcing.
Frequent cleaning of the steam cylinder by
removing and flushing or by striking the side
of the cylinder potentially dislodges flakes that
can build up a “dam” in the drain lines. It is not
recommended that the cylinder be removed except
for replacement.
Chemicals should
never
be used to attempt
to prevent mineral build up in the cylinder or
to dissolve minerals that accumulate.
Chemical treatment may affect conductivity.
Only untreated tap water is recommended for
use in the humidifier.
