FOAMING: The phenomenon which can occur in
water when the impurities, already in the water reach
an excess concentration as a result of boiling away
pure water and the continued boiling action agitating
the contained water. The humidifier electronics are
designed to prevent this occurrence although in
extreme cases, water will foam with little concentration
making it necessary to have the drain time of the
water, contained in the cylinder, increased. Foaming
is normally caused by short cycling, a restricted drain,
or back pressure. The foam, generated in these
instances, is conductive and may lead to false full
cylinder indication if the level of the foam approaches
the top of the cylinder.
BACK PRESSURE: The restriction of steam flow
caused by long steam runs, improperly sloped steam
lines, elbows changing the direction of steam flow from
horizontal to vertical without a drain leg, any plumbing
detail allowing the accumulation of condensate,
undersized steam line, improper steam distributor,
downward air flow onto the distributor causing excess
static pressure at the steam outlets, or high static
pressure ducts (not probable). To overcome excess
static pressure in the duct, a fill cup extension kit
should be used. In down flow applications, a down
flow distributor should be used, but in some cases the
fill cup extension will also be required.
RESET UNIT (HUMIDIFIER): To reset the
humidifier, the auto on/off/drain switch at the front of
the humidifier should be switch to the “Off” position for
a minimum of five seconds and then switched back to
the “On” position.
MONITORED LEG: Refers to the primary wire to
the cylinder which loops through the current sensing
devise of the main PCB. This wire is terminated at the
red cylinder plug at the cylinder.
STARTING POINT
MES-U
Auto On/Off/Drain switch in “On” position - unit will not fill:
When the on/off control circuit is made and the
“auto on/off/drain” switch is pushed to “on”, the 24 volt
holding coil of the primary contactor should energize.
The resulting magnetic pull closes the high voltage
contacts with a distinct and audible “clunk”. If the
contactor will not make, then inspect the following
while referring to the wiring diagram:
1. Check for 24 Vac across terminals 18 and 26
on PC board.
2. Jumper the humidistat on external control
terminal strip. If contactor operates, then
control system is at fault.
3. The low voltage 3 amp fuse located in the
control box could be blown.
4. The contactor holding coil could be open or
shorted.
5. The switch could be defective.
Recheck that the “auto on/off/drain” switch is still
at “on”. If it is, then shut off the main disconnect and
check fuses or breaker of the main disconnect. If they
are serviceable, turn power back on.
To test for a defective “auto on/off/drain” switch,
connect a wire from the fuse directly to terminal 6 on
the external controls strip. If the contactor activates,
the “on” side of the switch is defective. If the contactor
does not activate, the PC board could be defective.
If the 3 amp control fuse blows when the wire from
the fuse touches terminal 6 on the external controls
strip, contactor holding coil could be shorted. Replace
contactor if necessary.
After the necessary components have been
replaced and the contactor pulls in, there is line
voltage to the cylinder and the control sequence can
begin.
Approximately 30 seconds after the contactor pulls
in, the fill valve coil should energize. There is also a
visible fill relay on the printed circuit board. It is the
one located farthest from the C.T. core. The points on
this relay must be touching in order for the fill valve coil
to be energized.
If the points will not touch after the built-in time
delay, then the sensor input may be interfering. To
confirm, remove the black and red sensor wires from
the terminals 6 and 10 on the PC board. Wait 30
seconds and if the fill relay points not touch, then
sensor should be replaced. If they do not touch, then
the basic PC board could be faulty. To confirm,
disconnect the red wire from terminal 18 and touch it
to terminal 14. If the fill valve coil activates then the
basic PC board should be replaced. If it still does not
activate then the fill valve coil should be replaced.
Having changed the necessary components, water
starts filling the cylinder and begins to submerge the
electrodes. Because of the high voltage across the
electrodes, the water can now conduct electricity.
Red “Change Cylinder” light on - Water at top of cylinder:
This is a common occurrence on start-up. See
Start-Up and Operation section of this manual.
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