MES-U Electrode
Steam Humidifiers
Installation, Operation,
Maintenance, Spare Parts, and
Exploded Views Guide
IMPORTANT: Read and save this guide for future
reference. This guide to be left with equipment owner.
Form 03-111 Rev. 1
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Figure #1
Operation Schematic
INSTALLATION
RECEIVING EQUIPMENT
1. Check packing slip to ensure ALL material has
been received.
CONDENSATE RETURN
(OPTIONAL)
2. Inspect box for damage and note on shipping
waybill accordingly.
FILL
CUP
STEAM HOSE
1” AIR
GAP
1
2
3
3. After unpacking, inspect unit for damage and if
damage is found, advise shipper as soon as
possible.
ELECTRODES
1. INLET CHAMBER
2. FILL CHAMBER
4. Inspect unit (humidifier) to ensure it is the correct
model, phase, and voltage. If any are incorrect,
advise the factory or your local representative
immediately.
3. WATER OVERFLOW
CHAMBER (SAFETY DRAIN
IN CASE OF FILL VALVE/
CONTROL BOARD FAILURE)
CYLINDER
NOTE: All products are shipped on an F.O.B.
factory basis. Any and all damage, loss, or breakage
claims are to be made directly to the shipping
company.
STRAINER
FILL
VALVE
TAP
WATER
SUPPLY
DRAIN
VALVE
DRAIN
PAN
DRAIN
CONNECTION
The NORTEC MES-U electrode humidifier is the
culmination of many years of research and
development in the electrode humidifier industry. This
unit has been built by skilled craftspeople and
thoroughly tested before shipment and should, if the
following instructions are observed, provide many
years of trouble-free operation.
DRAIN CANAL
(OPEN TO ATMOSPHERE)
An electronic timer uses the rate of amp fall to
determine the water level. The objective is to
concentrate current-carrying minerals in the cylinder
so that a smaller volume of water is required to
produce the rated steam output.
FOR HUMIDIFIERS INSTALLED IN THE CITY
OF LOS ANGELES: A city of Los Angeles approved
spring-loaded double ball CHECK VALVE should be
supplied and installed by the contractor on each of the
potable water inlets to each humidifier.
This achieves the longest life for the disposable
cylinder because of minimal electrode coverage and
use of less energy because the high concentration
allows a minimal drain rate.
Recommended valve manufacturer: Watts
Regulator (phone 508-688-1811), model #7, size 3/8”
NPT inlet and outlet.
When 90% F.L.A. is reached, the fill valve will
open refilling cylinder to 110% F.L.A. On occasion,
the drain valve will also come on if water level is too
low, indicating too high a concentration and the
requirement for a dilution of the water in the cylinder.
Each drain line from these humidifiers shall be
routed, without dips or sags, to terminate above the
flood level rim of a City of Los Angeles approved
indirect waste receptor.
No combustible materials shall be placed in the
duct and/or the air plenum.
If the water reaches top of cylinder before 110%
F.L.A., the fill valve shuts off via the sensor and
fill-boil-fill-boil cycle continues, cycling off the red high
water sensor light until the concentration becomes
high enough to reach 110% F.L.A. The above
described control process will then take over.
PRINCIPAL OF OPERATION
When the humidistat calls, the cylinder fills to
110% of the Full Load Amperage (F.L.A.) or to the top
of the cylinder, whichever comes first. See Figure #1.
If it reaches 110% F.L.A. the water heats and boils
away to a level giving 90% F.L.A.
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for water pressure from 30 to 85 psi and are
protected by the built-in strainer.
WATER SUPPLY AND PLUMBING
1. The orifice in the fill valve is sized for an extended
water pressure range of 30 to 85 psi.
4. For inlet water pressure outside this range, the
factory should be contacted. (See Water Supply
and Plumbing section of this manual.)
2. For water pressure between 15 and 30 psi, notify
the factory and the next larger size fill valve will be
supplied.
START-UP AND OPERATION
3. For cases below 15 psi, notify the factory and a fill
valve with an oversized orifice will be supplied.
Check to see that the unit is securely mounted on
a level surface with the proper drain and water supply.
Check for correct voltage with appropriately sized
service. Check that the steam distributor, steam
supply hose, and condensate line are correctly
installed and routed back to the unit. Ensure that the
external control humidistat is located in an area to
properly sense the relative humidity to be maintained
by the humidifier, and that the interconnecting low
voltage wires between the humidistat and the unit’s
control terminal strip are in accordance with the wiring
diagram.
4. For cases above 85 psi, install a pressure
reducing valve in the water feed line to the unit.
5. With extremely dirty or muddy water sources, e.g.,
some well sources, ensure proper filtration by
adding an external filter to the water line entering
the unit. (Consult factory for accessories such as
filters.)
6. DO NOT use completely demineralized water with
this unit as it is the minerals that allow the
electrode principle to work.
Check all electrical connections for wires which
may have become loose in shipping. Components
damaged due to loose connections are NOT under
warranty.
7. DO NOT use a hot water source as it will cause
deposits that will eventually block the fill valve
orifice.
Check electrode plugs to ensure they are pressed
firmly onto the electrode pins. Important: Loose
connections will cause overheating of the cylinder
plugs, possibly melting the plugs and/or cylinder.
WATER CONNECTION
Figure #2
Bottom View of MES-U Unit
Open the isolating valve in the feed water line to
the unit.
3/8" Cold Water
Olive Connection
Make sure the humidistat is set high enough to call
for humidification.
Turn on the main disconnect in the primary service
feeding the unit and check that unit has power at the
primary terminal block.
PUSH THE AUTO ON/OFF/DRAIN SWITCH TO
“ON”.
7/8" Drain
Connection
Water will start to enter the cylinder through its
bottom port and rise in the cylinder to a point
determined by the solid-state control circuitry.
Use 7/8" I.D. Hose From Factory
1. A copper compression olive type coupling for 1/4"
O.D. soft copper tubing is provided with unit and
requires no soldering for the water connection to
the unit. See Figure #2.
It is not unusual upon initial start-up for the
water to fill the cylinder and cycle on the red high
water sensor light.
The red light simply acts as a safety to shut off the
fill valve and prevent over-filling. With the red light on,
the water in the cylinder will continue to heat and, after
a few minutes, start to boil. After the boiling action of
the water has lowered the water level below the
2. An isolating valve should ALWAYS be placed in
the feed water line allowing service of the fill valve.
3. Each unit is fitted with a fill solenoid valve located
on the base drain pan. Flow orifices are designed
sensor at the top of the cylinder, the red light will go
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out and the fill solenoid will again open until the
cylinder is again full.
cylinder is completely used as indicated by the red
high water sensor light illuminated on the cabinet.
When this condition is reached, a new replacement
cylinder is to be installed.
This cycling of the red light and fill valve will
continue until the unit’s full output capacity is reached
after which the water level will automatically lower
itself in the cylinder. (The increased concentration
allows for lower electrode coverage while maintaining
the same output.) When a stabilized condition is
reached the water will be boiling close to the cylinder
seam level. The solid state circuitry will maintain the
proper concentration in the cylinder by introducing
short drains only when necessary.
NOTE: Red light may come on during initial
start-up but does not mean cylinder replacement. See
Start Up and Operation section of this manual.
Consult factory or agent for replacement. Quote
the cylinder model from the white 3-digit label on the
cylinder or quote model, voltage, and serial number
from unit specification label.
If the cylinder is manually drained the above
process will repeat itself.
WHEN TO REPLACE THE STEAM CYLINDER
The steam cylinder is disposable and must be
replaced at the end of cylinder life. Cylinder life is
dependent on water supply conditions and humidifier
usage. Failure to replace the cylinder at the end of
cylinder life may result in unit damage. NORTEC is
not responsible for any damages resulting from, or
attributable to, the failure to replace a used cylinder
(see Manufacturer’s Warranty).
Low Water Conductivity
Should normalization of the unit be required
immediately after start-up, the installer may speed up
the process by artificially increasing water conductivity.
During a fillcycle, the installer should dissolve half a
teaspoon of table salt (no more) in a cup of water and
add it to the cylinder by means of the fill cup attached
to the plumbing section.
Figure #4
Cylinder Removal
Open the plumbing compartment and add salt
solution through cylinder outlet. Excessive amounts of
salt will result in erratic operation of the unit; however,
normalization of the unit will occur automatically
through the solid-state control sequence.
CAPACITY ADJUSTMENT
Figure #3
Adjustable Pot
Adjustable
Capacity Pot
The MES-U series of humidifiers come with
adjustable capacity (AC) PC boards. These boards
have a pot labeled 20 to 100%. See Figure # 3.
REMOVING THE OLD CYLINDER
CYLINDER REPLACEMENT
n
See Figure # 4.
After an extended period of operation, in
accordance with life expectancy information, the
1. Turn off the water supply to unit.
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2. The old cylinder must be drained completely
before removing. This is done by pushing the auto
on/off/drain switch to the “drain” position.
3. The white sensor plug on all units is for the sensor
pin, which always goes on the single pin offset
from the others. See Figure # 5.
3. When completely drained, push the auto
4. Ensure that cylinder plugs are very snug on the
pins.
on/off/drain switch to the “off” position.
4. Open the main disconnect during the entire
cylinder change operation.
5. For loose fitting plugs, a temporary solution is to
squeeze plugs with a pair of pliers before
installing. Since loose plugs may generate
enough heat to melt and destroy the plug and
cylinder new plugs must be ordered.
5. The power wires to the cylinder are attached by
cylinder plugs to the electrode pins on top of the
cylinder. Pull these plugs vertically off the pins.
See Figure # 4.
MAINTENANCE
6. Using slot screwdriver, loosen the steam hose
clamp(s) and pull steam hose off vertically.
WARNING! The plumbing and electrical
compartments contain high voltage components and
wiring. The access cover is attached with screws.
Access should be limited to authorized personnel only.
7. The cylinder is now ready to be lifted out of the
unit.
EXTENDED SHUTDOWN
INSTALLING THE NEW CYLINDER
Figure #5
Plugs
Before disconnecting power to the humidifier for a
period of extended shutdown, ALWAYS DRAIN the
cylinder first. Otherwise, the electrodes are subject to
harmful corrosion which drastically shortens the
cylinder life. Do NOT leave the switch in the DRAIN
position indefinitely as the drain coil could burn out.
Leave the switch in the OFF position and “open” the
main external fused disconnect to stop power to the
humidifier. Close the shut off valve in the water supply
line feeding the humidifier.
White
Sensor Plug
1Ø
Sensor Pin
Cylinder
Plug
TROUBLESHOOTING
Cylinder Pin
Cylinder Pin
TERMS USED
Sensor Pin
F.L.A. (Full Load Amps): Refers to amps listed on
the humidifier specification label.
3Ø
Cylinder Pin
Cylinder Pin
SHORT CYCLING: When the ‘on time’ of the
humidifier is less than ten minutes upon a call for
humidity. To correct short cycling, all humidifiers have
a capacity adjustment which allows the output of the
humidifier to be reduced to as low as 20% of rated
output, thus extending the ‘on time’ required to
maintain output.
Cylinder Pin
1. The reverse procedure should be followed to
install a new cylinder. The main disconnect is to
be left open until the cylinder is completely
installed and reconnected.
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
2. Ensure that the cylinder mounting stubs are
seated properly in the allotted side mounting slots
within the unit.
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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.
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.
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.
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.
Return wires to normal.
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.
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.
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.
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.
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.
STARTING POINT
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:
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.
1. Check for 24 Vac across terminals 18 and 26 on
PC board.
Red “Change Cylinder” light on - Water at top of cyl-
inder:
2. Jumper the humidistat on external control terminal
strip. If contactor operates, then control system is
at fault.
This is a common occurrence on start-up. See
Start-Up and Operation section of this manual.
3. The low voltage 3 amp fuse located in the control
box could be blown.
If the cylinder is old, it indicates end of cylinder life.
Time to replace the cylinder. See “When To Replace
The Steam Cylinder” section of this manual.
4. The contactor holding coil could be open or
shorted.
5. The switch could be defective.
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Red “Change Cylinder” light on - Water NOT at top of
cylinder:
Water foaming to top of cylinder causing false full
cylinder indication. This also may be accompanied by
arcing (flashing) inside cylinder. Refer to “Terms
Used” regarding foaming.
Water remains at high level and won’t concentrate:
This is normal on cold start-up and can be
accelerated by adding maximum 1/2 tsp. of dissolved
salt to the cylinder (through the plastic fill cup) on fill
cycle. See “Low Water Conductivity” section of this
manual.
If unit has been operating extensively, observe for
normal fill-boil-fill-boil cycle; no drain should be
occurring. If drain occuring, check for leaking drain
valve or back pressure.
Water beyond top of cylinder up into spout:
If the red light is not on and fill is still activated,
jumper across the connection of sensor on basic PC
board. If fill remains on when connection is jumped,
then basic PC board is faulty. If fill shuts off, then
verify primary voltage to cylinder (contactor
energized). If primary voltage is present, the high
water sensor PCB is defective.
Unit drains continually:
May be caused by foaming and/or back pressure,
or leaking drain valve.
Cylinder is almost empty, check for magnetic pull
on drain solenoid indicating miswiring. If no pull, drain
actuator is blocked open; remove, disassemble and
clean.
If drain is occurring through activated drain valve,
valve is miswired or electronics are faulty - consult
factory.
If drain is occurring through the overflow on the fill
cup, this is due to abnormal restriction on the steam
line and back pressure forces water out of the cylinder;
therefore, water cannot concentrate and level must
stay high; review installation of steam line to ensure no
blockages or excessive static pressure in air system.
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DIMENSIONS
WIDTH in.(cm)
MES-U / MES-P
DEPTH
WIDTH in.(cm)
HEIGHT
in.(cm)
(REMOTE ELECTRICAL) (ATTACHED ELECTRICAL)
in.(cm)
5 *
10
15
20
25
30
6.6 (16.7 cm)
6.6 (16.7 cm)
8.4 (21.3 cm)
8.4 (21.3 cm)
10.5 (26.7 cm)
10.5 (26.7 cm)
8.6 (21.9 cm)
8.6 (21.9 cm)
10.5 (26.7 cm)
10.5 (26.7 cm)
10.5 (26.7 cm)
10.5 (26.7 cm)
10.7 (27.1 cm)
10.7 (27.1 cm)
12.6 (32.2 cm)
12.6 (32.2 cm)
12.6 (32.2 cm)
12.6 (32.2 cm)
13.5 (34.4 cm)
17.3 (43.9 cm)
19.4 (49.3 cm)
19.4 (49.3 cm)
21.3 (54.0 cm)
21.3 (54.0 cm)
WEIGHTS (DRY)
3
CONFIGURATION
1
2
4
5
6
7
8
9
MES-U / MES-P
lbs(kg)
lbs(kg)
lbs(kg)
lbs(kg)
lbs(kg)
lbs(kg)
lbs(kg)
lbs(kg)
lbs(kg)
5*
8.2 (3.7) 9.6 (4.3) 9.0 (4.1) 10.4 (4.7) 13.7 (6.2) 13.1 (6.0) 14.5 (6.6) 8.8 (4.0) 13.0 (5.9)
8.7 (4.0) 10.1 (4.6) 9.5 (4.3) 10.9 (4.9) 14.2 (6.4) 13.7 (6.2) 15.0 (6.8) 9.4 (4.2) 13.5 (6.1)
12.6 (5.7) 13.9 (6.3) 13.4 (6.1) 14.8 (6.7) 22.0 (10.0) 21.5 (9.7) 22.9 (10.4) 13.2 (6.0) 21.3 (9.7)
14.1 (6.4) 15.4 (7.0) 14.9 (6.7) 16.2 (7.4) 23.5 (10.7) 23.0 (10.4) 24.3 (11.0) 14.7 (6.7) 22.8 (10.3)
10
15/20
25/30
NOTES:
1. FOR HEIGHT OF 5 LB PVC USE HEIGHT OF 10 LB MODEL.
2. PVC = PRIMARY VOLTAGE CONNECTION.
3. MODEL SHOWN: 163-91X5 (CONFIGURATION #5) WITH
CP (CLOSED PLUMBING) COVER REMOVED.
condair
TOP VIEW
AUTO/ON
OFF
condair
DRAIN
FRONT VIEW
LEFT VIEW
MES-U/MES-P HUMIDIFIER
MESU DIM 10/19/98
PHYSICAL DATA
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PRIMARY
POWER
24 VAC
INPUT
(By Others)
PRIMARY
CONTACTOR
24 vac
ON/OFF
CONTROLS
(By Others)
PRIMARY TERMINAL
BLOCK
.187 insulated fast-on
For field connection
(provided with
PVC unit)
3 AMP
FUSE
ON
SWITCH OFF
DRAIN
HIGH WATER
SENSOR PCB
FILL
VALVE
DRAIN
VALE
HIGH VOLTAGE
ELECTRODE LEADS
(BY OTHERS OR
INCLUDED WITH
PVC UNIT)
CHANGE
CYLINDER
LAMP
-2 LEADS
FOR SINGLE
PHASE
-3 LEADS
FOR THREE
PHASE
CURRENT
TRANSFORMER
MES-U
CONTROL
BOARD
STEAM CYLINDER
NOTE: SOLID LINES WIRING BY OTHERS
MES-U INTERNAL AND FIELD WIRING
(For PVC or LVC unit with remote or attached electrical)
WIRING DIAGRAM number 150-6240 REV. B
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LIMITED WARRANTY
NORTEC INDUSTRIES INCORPORATED and/or NORTEC AIR
CONDITIONING INDUSTRIES LIMITED (hereinafter collectively referred to as THE
COMPANY), warrant for a period of two years from date of shipment, that THE
COMPANY’s manufactured and assembled products, not otherwise expressly
warranted (with the exception of the cylinder) are free from defects in material and
workmanship. No warranty is made against corrosion, deterioration, or suitability of
substituted materials used as a result of compliance with government regulations.
THE COMPANY’s obligations and liabilities under this warranty are limited to
furnishing replacement parts to the customer, F.O.B. THE COMPANY’s factory,
providing the defective part(s) is returned freight prepaid by the customer. Parts used
for repairs are warranted for the balance of the term of the warranty on the original
humidifier or 90 days, whichever is longer.
The warranties set forth herein are in lieu of all other warranties expressed or
implied by law. No liability whatsoever shall be attached to THE COMPANY until said
products have been paid for in full and then said liability shall be limited to the original
purchase price for the product. Any further warranty must be in writing, signed by an
officer of THE COMPANY.
THE COMPANY’s limited warranty on accessories, not of NORTEC’s
manufacture, such as controls, humidistats, pumps, etc. is limited to the warranty of the
original equipment manufacturer from date of original shipment of humidifier.
THE COMPANY makes no warranty and assumes no liability unless the
equipment is installed in strict accordance with a copy of the catalog and installation
manual in effect at the date of purchase and by a contractor approved by THE
COMPANY to install such equipment.
THE COMPANY makes no warranty and assumes no liability whatsoever for
consequential damage or damage resulting directly from misapplication, incorrect sizing
or lack of proper maintenance of the equipment.
THE COMPANY retains the right to change the design, specification and
performance criteria of its products without notice or obligation.
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Model # :_________________________
Serial # :_________________________
Cylinder # :_______________________
Cylinder Last Replaced:
_________________________
MTH/DAY/YR
_________________________
MTH/DAY/YR
_________________________
MTH/DAY/YR
NORTEC INDUSTRIES INC.
NORTEC AIR CONDITIONING
INDUSTRIES LTD*.
P.O. Box 698
826 Proctor Avenue
Ogdensburg, NY 13669
2740 Fenton Road
Ottawa, ON K1T 3T7
A WMH COMPANY
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