Emerson Liebert ICOM-DO Installation Manual download pdf (Page 69)

Humidifier

Extended Shutdown

Always drain the cylinder before disconnecting power to the humidifier for a period of extended shut-

down. Otherwise, the electrodes are subject to harmful corrosion, which drastically shortens the cylin-

der life. Do not leave the switch in the DRAIN position indefinitely because 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 shutoff valve in the water supply line feeding the humidifier.

A.1.6 Humidifier Troubleshooting

Terms Used

• FLA (Full Load Amps) are amps listed on the humidifier specification label.

• Short cycling occurs when the humidifier’s “On time” is less than 10 minutes upon a call for

humidity. To correct short cycling, all humidifiers have a capacity adjustment that allows the out-

put of the humidifier to be reduced to as low as 20% of rated output, thus extending the “on time”

required to maintain output.

• Foaming can occur when the impurities already in water reach an excess concentration as a

result of boiling away water and continued boiling agitates the contained water. The humidifier

electronics are designed to prevent foaming, although in extreme cases water will foam with little

concentration, making it necessary to increase the drain time of the water contained in the cylin-

der. 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 is 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 pres-

sure in the duct, use a fill cup extension kit. In downflow applications, a downflow distributor

should be used, but in some cases the fill cup extension will also be required.

• Reset unit (humidifier): To reset the humidifier, switch the auto On/Off/Drain switch at the front

of the humidifier to the Off position for at least five seconds, then switch it back to the On position.

• Monitored leg is the primary wire to the cylinder that loops through the current sensing device

of the main PCB. This wire ends at the red cylinder plug at the cylinder.

A.2 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 24V

holding coil of the primary contactor should energize. The resulting magnetic pull closes the high volt-

age contacts with a distinct and audible “clunk.” If the contactor will not make the connection, then

inspect the following while referring to the wiring diagram:

• Check for 24V across terminals 18 and 26 on the PC board.

• The low-voltage 3A fuse located in the control box may be blown.

• The contactor holding coil may be open or shorted.

• The switch may be defective.

Recheck that the Auto On/Off/Drain switch is still On. If it is, 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 3A control fuse blows when the wire from the fuse touches Terminal 6 on the external controls

strip, the contactor holding coil may 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.

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Emerson Liebert ICOM-DO Installation Manual Page 69

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