MES-U ElectrodeSteam Humidifiers

Installation, Operation,Maintenance, Spare Parts, and

Exploded Views Guide

IMPORTANT: Read and save these instructions. Thisguide to be left with equipment owner.

Form 99-111

Table of Contents

INSTALLATION 1

– RECEIVING EQUIPMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

– PRINCIPAL OF OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

– WATER SUPPLY AND PLUMBING . . . . . . . . . . . . . . . . . . . . . . . . . . 2

– WATER CONNECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

– START-UP AND OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

– CAPACITY ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

– CYLINDER REPLACEMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

– WHEN TO REPLACE THE STEAM CYLINDER . . . . . . . . . . . . . . . . . . . 3– REMOVING THE OLD CYLINDER . . . . . . . . . . . . . . . . . . . . . . . . . 3– INSTALLING THE NEW CYLINDER . . . . . . . . . . . . . . . . . . . . . . . . 4

MAINTENANCE 4

– EXTENDED SHUTDOWN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

TROUBLESHOOTING 4

– TERMS USED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

– STARTING POINT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

– PHYSICAL DIMENSIONS DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . 7

– WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

– SPARE PARTS LIST. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

– EXPLODED VIEWS DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

INSTALLATION

RECEIVING EQUIPMENT

1. Check packing slip to ensure ALL material hasbeen received.

2. Inspect box for damage and note on shippingwaybill accordingly.

3. After unpacking, inspect unit for damage and ifdamage is found, advise shipper as soon aspossible.

4. Inspect unit (humidifier) to ensure it is the correctmodel, phase, and voltage. If any are incorrect,advise the factory or your local representativeimmediately.

NOTE: All products are shipped on an F.O.B.factory basis. Any and all damage, loss, or breakageclaims are to be made directly to the shippingcompany.

The NORTEC MES-U electrode humidifier is theculmination of many years of research anddevelopment in the electrode humidifier industry. Thisunit has been built by skilled craftspeople andthoroughly tested before shipment and should, if thefollowing instructions are observed, provide manyyears of trouble-free operation.

FOR HUMIDIFIERS INSTALLED IN THE CITYOF LOS ANGELES: A city of Los Angeles approvedspring-loaded double ball CHECK VALVE should besupplied and installed by the contractor on each of thepotable water inlets to each humidifier.

Recommended valve manufacturer: WattsRegulator (phone 508-688-1811), model #7, size 3/8”NPT inlet and outlet.

Each drain line from these humidifiers shall berouted, without dips or sags, to terminate above theflood level rim of a City of Los Angeles approvedindirect waste receptor.

No combustible materials shall be placed in theduct and/or the air plenum.

PRINCIPAL OF OPERATION

When the humidistat calls, the cylinder fills to110% of the Full Load Amperage (F.L.A.) or to the topof the cylinder, whichever comes first. See Figure #1.

If it reaches 110% F.L.A. the water heats and boilsaway to a level giving 90% F.L.A.

An electronic timer uses the rate of amp fall todetermine the water level. The objective is toconcentrate current-carrying minerals in the cylinderso that a smaller volume of water is required toproduce the rated steam output.

This achieves the longest life for the disposablecylinder because of minimal electrode coverage anduse of less energy because the high concentrationallows a minimal drain rate.

When 90% F.L.A. is reached, the fill valve willopen refilling cylinder to 110% F.L.A. On occasion,the drain valve will also come on if water level is toolow, indicating too high a concentration and therequirement for a dilution of the water in the cylinder.

If the water reaches top of cylinder before 110%F.L.A., the fill valve shuts off via the sensor andfill-boil-fill-boil cycle continues, cycling off the red highwater sensor light until the concentration becomeshigh enough to reach 110% F.L.A. The abovedescribed control process will then take over.

- 1 -

Figure #1Operation Schematic

CONDENSATE RETURN(OPTIONAL)

1” AIRGAP

FILLCUP

1. INLET CHAMBER

3. WATER OVERFLOWCHAMBER (SAFETY DRAININ CASE OF FILL VALVE/CONTROL BOARD FAILURE)

STRAINER FILLVALVE

TAPWATERSUPPLY

DRAINCONNECTION

DRAINPAN

DRAIN CANAL(OPEN TO ATMOSPHERE)

DRAINVALVE

CYLINDER

1 2 3

2. FILL CHAMBER

STEAM HOSE

ELECTRODES

WATER SUPPLY AND PLUMBING

1. The orifice in the fill valve is sized for an extendedwater pressure range of 30 to 85 psi.

2. For water pressure between 15 and 30 psi, notifythe factory and the next larger size fill valve will besupplied.

3. For cases below 15 psi, notify the factory and a fillvalve with an oversized orifice will be supplied.

4. For cases above 85 psi, install a pressurereducing 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 byadding an external filter to the water line enteringthe unit. (Consult factory for accessories such asfilters.)

6. DO NOT use completely demineralized water withthis unit as it is the minerals that allow theelectrode principle to work.

7. DO NOT use a hot water source as it will causedeposits that will eventually block the fill valveorifice.

WATER CONNECTION

1. A copper compression olive type coupling for 1/4"O.D. soft copper tubing is provided with unit andrequires no soldering for the water connection tothe unit. See Figure #2.

2. An isolating valve should ALWAYS be placed inthe feed water line allowing service of the fill valve.

3. Each unit is fitted with a fill solenoid valve locatedon the base drain pan. Flow orifices are designed

for water pressure from 30 to 85 psi and areprotected by the built-in strainer.

4. For inlet water pressure outside this range, thefactory should be contacted. (See Water Supplyand Plumbing section of this manual.)

START-UP AND OPERATION

Check to see that the unit is securely mounted ona level surface with the proper drain and water supply.Check for correct voltage with appropriately sizedservice. Check that the steam distributor, steamsupply hose, and condensate line are correctlyinstalled and routed back to the unit. Ensure that theexternal control humidistat is located in an area toproperly sense the relative humidity to be maintainedby the humidifier, and that the interconnecting lowvoltage wires between the humidistat and the unit’scontrol terminal strip are in accordance with the wiringdiagram.

Check all electrical connections for wires whichmay have become loose in shipping. Componentsdamaged due to loose connections are NOT underwarranty.

Check electrode plugs to ensure they are pressedfirmly onto the electrode pins. Important: Looseconnections will cause overheating of the cylinderplugs, possibly melting the plugs and/or cylinder.

Open the isolating valve in the feed water line tothe unit.

Make sure the humidistat is set high enough to callfor humidification.

Turn on the main disconnect in the primary servicefeeding the unit and check that unit has power at theprimary terminal block.

PUSH THE AUTO ON/OFF/DRAIN SWITCH TO“ON”.

Water will start to enter the cylinder through itsbottom port and rise in the cylinder to a pointdetermined by the solid-state control circuitry.

It is not unusual upon initial start-up for thewater to fill the cylinder and cycle on the red highwater sensor light.

The red light simply acts as a safety to shut off thefill valve and prevent over-filling. With the red light on,the water in the cylinder will continue to heat and, aftera few minutes, start to boil. After the boiling action ofthe water has lowered the water level below thesensor at the top of the cylinder, the red light will go

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Figure #2Bottom View of MES-U Unit

3/8" Cold WaterOlive Connection

7/8" DrainConnection

Use 7/8" I.D. Hose From Factory

out and the fill solenoid will again open until thecylinder is again full.

This cycling of the red light and fill valve willcontinue until the unit’s full output capacity is reachedafter which the water level will automatically loweritself in the cylinder. (The increased concentrationallows for lower electrode coverage while maintainingthe same output.) When a stabilized condition isreached the water will be boiling close to the cylinderseam level. The solid state circuitry will maintain theproper concentration in the cylinder by introducingshort drains only when necessary.

If the cylinder is manually drained the aboveprocess will repeat itself.

Low Water Conductivity

Should normalization of the unit be requiredimmediately after start-up, the installer may speed upthe process by artificially increasing water conductivity.During a fillcycle, the installer should dissolve half ateaspoon of table salt (no more) in a cup of water andadd it to the cylinder by means of the fill cup attachedto the plumbing section.

Open the plumbing compartment and add saltsolution through cylinder outlet. Excessive amounts ofsalt will result in erratic operation of the unit; however,normalization of the unit will occur automaticallythrough the solid-state control sequence.

CAPACITY ADJUSTMENT

The MES-U series of humidifiers come withadjustable capacity (AC) PC boards. These boardshave a pot labeled 20 to 100%. See Figure # 3.

CYLINDER REPLACEMENT

After an extended period of operation, inaccordance with life expectancy information, the

cylinder is completely used as indicated by the redhigh water sensor light illuminated on the cabinet.When this condition is reached, a new replacementcylinder is to be installed.

NOTE: Red light may come on during initialstart-up but does not mean cylinder replacement. SeeStart Up and Operation section of this manual.

Consult factory or agent for replacement. Quotethe cylinder model from the white 3-digit label on thecylinder or quote model, voltage, and serial numberfrom unit specification label.

WHEN TO REPLACE THE STEAM CYLINDER

The steam cylinder is disposable and must bereplaced at the end of cylinder life. Cylinder life isdependent on water supply conditions and humidifierusage. Failure to replace the cylinder at the end ofcylinder life may result in unit damage. NORTEC isnot responsible for any damages resulting from, orattributable to, the failure to replace a used cylinder(see Manufacturer’s Warranty).

REMOVING THE OLD CYLINDER

� See Figure # 4.

1. Turn off the water supply to unit.

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AdjustableCapacity Pot

Figure #3Adjustable Pot

Figure #4Cylinder Removal

2. The old cylinder must be drained completelybefore removing. This is done by pushing the autoon/off/drain switch to the “drain” position.

3. When completely drained, push the autoon/off/drain switch to the “off” position.

4. Open the main disconnect during the entirecylinder change operation.

5. The power wires to the cylinder are attached bycylinder plugs to the electrode pins on top of thecylinder. Pull these plugs vertically off the pins.See Figure # 4.

6. Using slot screwdriver, loosen the steam hoseclamp(s) and pull steam hose off vertically.

7. The cylinder is now ready to be lifted out of theunit.

INSTALLING THE NEW CYLINDER

1. The reverse procedure should be followed toinstall a new cylinder. The main disconnect is tobe left open until the cylinder is completelyinstalled and reconnected.

2. Ensure that the cylinder mounting stubs areseated properly in the allotted side mounting slotswithin the unit.

3. The white sensor plug on all units is for the sensorpin, which always goes on the single pin offsetfrom the others. See Figure # 5.

4. Ensure that cylinder plugs are very snug on thepins.

5. For loose fitting plugs, a temporary solution is tosqueeze plugs with a pair of pliers beforeinstalling. Since loose plugs may generateenough heat to melt and destroy the plug andcylinder new plugs must be ordered.

MAINTENANCEWARNING! The plumbing and electrical

compartments contain high voltage components andwiring. The access cover is attached with screws.Access should be limited to authorized personnel only.

EXTENDED SHUTDOWN

Before disconnecting power to the humidifier for aperiod of extended shutdown, ALWAYS DRAIN thecylinder first. Otherwise, the electrodes are subject toharmful corrosion which drastically shortens thecylinder life. Do NOT leave the switch in the DRAINposition indefinitely as the drain coil could burn out.Leave the switch in the OFF position and “open” themain external fused disconnect to stop power to thehumidifier. Close the shut off valve in the water supplyline feeding the humidifier.

TROUBLESHOOTING

TERMS USED

F.L.A. (Full Load Amps): Refers to amps listed onthe humidifier specification label.

SHORT CYCLING: When the ‘on time’ of thehumidifier is less than ten minutes upon a call forhumidity. To correct short cycling, all humidifiers havea capacity adjustment which allows the output of thehumidifier to be reduced to as low as 20% of ratedoutput, thus extending the ‘on time’ required tomaintain output.

FOAMING: The phenomenon which can occur inwater when the impurities, already in the water reachan excess concentration as a result of boiling awaypure water and the continued boiling action agitatingthe contained water. The humidifier electronics aredesigned to prevent this occurrence although inextreme cases, water will foam with little concentrationmaking it necessary to have the drain time of thewater, contained in the cylinder, increased. Foaming

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Figure #5Plugs

CylinderPlug

Cylinder Pin

Cylinder Pin

Cylinder Pin

Cylinder Pin

Cylinder Pin

WhiteSensor Plug Sensor Pin

Sensor Pin

3Ø

1Ø

is normally caused by short cycling, a restricted drain,or back pressure. The foam, generated in theseinstances, is conductive and may lead to false fullcylinder indication if the level of the foam approachesthe top of the cylinder.

BACK PRESSURE: The restriction of steam flowcaused by long steam runs, improperly sloped steamlines, elbows changing the direction of steam flow fromhorizontal to vertical without a drain leg, any plumbingdetail allowing the accumulation of condensate,undersized steam line, improper steam distributor,downward air flow onto the distributor causing excessstatic pressure at the steam outlets, or high staticpressure ducts (not probable). To overcome excessstatic pressure in the duct, a fill cup extension kitshould be used. In down flow applications, a downflow distributor should be used, but in some cases thefill cup extension will also be required.

RESET UNIT (HUMIDIFIER): To reset thehumidifier, the auto on/off/drain switch at the front ofthe humidifier should be switch to the “Off” position fora minimum of five seconds and then switched back tothe “On” position.

MONITORED LEG: Refers to the primary wire tothe cylinder which loops through the current sensingdevise of the main PCB. This wire is terminated at thered cylinder plug at the cylinder.

STARTING POINT

Auto On/Off/Drain switch in “On” position - unit willnot fill:

When the on/off control circuit is made and the“auto on/off/drain” switch is pushed to “on”, the 24 voltholding coil of the primary contactor should energize.The resulting magnetic pull closes the high voltagecontacts with a distinct and audible “clunk”. If thecontactor will not make, then inspect the followingwhile referring to the wiring diagram:

1. Check for 24 Vac across terminals 18 and 26 onPC board.

2. Jumper the humidistat on external control terminalstrip. If contactor operates, then control system isat fault.

3. The low voltage 3 amp fuse located in the controlbox could be blown.

4. The contactor holding coil could be open orshorted.

5. The switch could be defective.

Recheck that the “auto on/off/drain” switch is stillat “on”. If it is, then shut off the main disconnect andcheck fuses or breaker of the main disconnect. If theyare 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 onthe external controls strip. If the contactor activates,the “on” side of the switch is defective. If the contactordoes not activate, the PC board could be defective.

If the 3 amp control fuse blows when the wire fromthe fuse touches terminal 6 on the external controlsstrip, contactor holding coil could be shorted. Replacecontactor if necessary.

Return wires to normal.

After the necessary components have beenreplaced and the contactor pulls in, there is linevoltage to the cylinder and the control sequence canbegin.

Approximately 30 seconds after the contactor pullsin, the fill valve coil should energize. There is also avisible fill relay on the printed circuit board. It is theone located farthest from the C.T. core. The points onthis relay must be touching in order for the fill valvecoil to be energized.

If the points will not touch after the built-in timedelay, then the sensor input may be interfering. Toconfirm, remove the black and red sensor wires fromthe terminals 6 and 10 on the PC board. Wait 30seconds and if the fill relay points not touch, thensensor should be replaced. If they do not touch, thenthe basic PC board could be faulty. To confirm,disconnect the red wire from terminal 18 and touch itto terminal 14. If the fill valve coil activates then thebasic PC board should be replaced. If it still does notactivate then the fill valve coil should be replaced.

Having changed the necessary components, waterstarts filling the cylinder and begins to submerge theelectrodes. Because of the high voltage across theelectrodes, the water can now conduct electricity.

Red “Change Cylinder” light on - Water at top of cyl-inder:

This is a common occurrence on start-up. SeeStart-Up and Operation section of this manual.

If the cylinder is old, it indicates end of cylinder life.Time to replace the cylinder. See “When To ReplaceThe Steam Cylinder” section of this manual.

- 5 -

Red “Change Cylinder” light on - Water NOT at top ofcylinder:

Water foaming to top of cylinder causing false fullcylinder indication. This also may be accompanied byarcing (flashing) inside cylinder. Refer to “TermsUsed” regarding foaming.

Water remains at high level and won’t concentrate:

This is normal on cold start-up and can beaccelerated by adding maximum 1/2 tsp. of dissolvedsalt to the cylinder (through the plastic fill cup) on fillcycle. See “Low Water Conductivity” section of thismanual.

If unit has been operating extensively, observe fornormal fill-boil-fill-boil cycle; no drain should beoccurring. If drain occuring, check for leaking drainvalve 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 PCboard. If fill remains on when connection is jumped,then basic PC board is faulty. If fill shuts off, thenverify primary voltage to cylinder (contactorenergized). If primary voltage is present, the highwater 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 pullon drain solenoid indicating miswiring. If no pull, drainactuator is blocked open; remove, disassemble andclean.

If drain is occurring through activated drain valve,valve is miswired or electronics are faulty - consultfactory.

If drain is occurring through the overflow on the fillcup, this is due to abnormal restriction on the steamline and back pressure forces water out of the cylinder;therefore, water cannot concentrate and level muststay high; review installation of steam line to ensure noblockages or excessive static pressure in air system.

- 6 -

- 7 -

MES-U/MES-P HUMIDIFIER

PHYSICAL DATA

MESU DIM 10/19/98

WEIGHTS (DRY)

DIMENSIONS

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) WITHCP (CLOSED PLUMBING) COVER REMOVED.

LEFT VIEWFRONT VIEW

TOP VIEW

condair

AUTO/ON

OFF

DRAINcondair

MES-U / MES-P DEPTH WIDTH in.(cm) WIDTH in.(cm) HEIGHT

in.(cm) (REMOTE ELECTRICAL) (ATTACHED ELECTRICAL) in.(cm)

5 * 6.6 (16.7 cm) 8.6 (21.9 cm) 10.7 (27.1 cm) 13.5 (34.4 cm)

10 6.6 (16.7 cm) 8.6 (21.9 cm) 10.7 (27.1 cm) 17.3 (43.9 cm)

15 8.4 (21.3 cm) 10.5 (26.7 cm) 12.6 (32.2 cm) 19.4 (49.3 cm)

20 8.4 (21.3 cm) 10.5 (26.7 cm) 12.6 (32.2 cm) 19.4 (49.3 cm)

25 10.5 (26.7 cm) 10.5 (26.7 cm) 12.6 (32.2 cm) 21.3 (54.0 cm)

30 10.5 (26.7 cm) 10.5 (26.7 cm) 12.6 (32.2 cm) 21.3 (54.0 cm)

CONFIGURATION 1 2 3 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)

10 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)

15/20 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)

25/30 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)

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2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

CHANGECYLINDER

LAMP

DRAINVALVE

FILLVALVE

ON

OFF

DRAIN

SWITCH

3 AMPFUSE

24 VACINPUT

CURRENTTRANSFORMER

ON/OFFCONTROLS

MES-UCONTROL

BOARD

MES-U INTERNAL AND FIELD WIRING(for PVC or LVC unit with remote or attached electrical)

WIRING DIAGRAM No. 85-3-1 Rev. 7 (9/21/98)

NOTE: SOLID LINES WIRING BY OTHERS

.187 insulated fast-onfor field connection

PRIMARYPOWER

HIGH WATERSENSOR PCB

HIGH VOLTAGEELECTRODE LEADS

(BY OTHERS ORINCLUDED WITH

PVC UNIT)

-2 LEADSFOR SINGLE

PHASE

-3 LEADSFOR THREE

PHASE

123 4

PRIMARY TERMINALBLOCK

(provided withPVC unit)

D

PRIMARYCONTACTOR

24 vac

LIMITED WARRANTY

NORTEC INDUSTRIES INCORPORATED and/or NORTEC AIRCONDITIONING INDUSTRIES LIMITED (hereinafter collectively referred to as THECOMPANY), warrant for a period of two years from date of shipment, that THECOMPANY’s manufactured and assembled products, not otherwise expresslywarranted (with the exception of the cylinder) are free from defects in material andworkmanship. No warranty is made against corrosion, deterioration, or suitability ofsubstituted materials used as a result of compliance with government regulations.

THE COMPANY’s obligations and liabilities under this warranty are limited tofurnishing 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 usedfor repairs are warranted for the balance of the term of the warranty on the originalhumidifier or 90 days, whichever is longer.

The warranties set forth herein are in lieu of all other warranties expressed orimplied by law. No liability whatsoever shall be attached to THE COMPANY until saidproducts have been paid for in full and then said liability shall be limited to the originalpurchase price for the product. Any further warranty must be in writing, signed by anofficer of THE COMPANY.

THE COMPANY’s limited warranty on accessories, not of NORTEC’smanufacture, such as controls, humidistats, pumps, etc. is limited to the warranty of theoriginal equipment manufacturer from date of original shipment of humidifier.

THE COMPANY makes no warranty and assumes no liability unless theequipment is installed in strict accordance with a copy of the catalog and installationmanual in effect at the date of purchase and by a contractor approved by THECOMPANY to install such equipment.

THE COMPANY makes no warranty and assumes no liability whatsoever forconsequential damage or damage resulting directly from misapplication, incorrect sizingor lack of proper maintenance of the equipment.

THE COMPANY retains the right to change the design, specification andperformance criteria of its products without notice or obligation.

Model # :_________________________

Serial # :_________________________

Cylinder # :_______________________

Cylinder Last Replaced:

_________________________MTH/DAY/YR

_________________________MTH/DAY/YR

_________________________MTH/DAY/YR

NORTEC INDUSTRIES INC.P.O. Box 698

826 Proctor AvenueOgdensburg, NY 13669

NORTEC AIR CONDITIONINGINDUSTRIES LTD*.2740 Fenton Road

Ottawa, ON K1T 3T7

A WMH COMPANY

PR

INT

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INC

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