Emerson DH Manuel D’Utilisation

False canister full 

indication

Foaming

Check drain valve to ensure that it drains freely. Check 

and replace if defective.
Check water supply. If commercially softened, 

reconnect to raw water supply. If connected to hot 

water reconnect to cold water.

Main 24 VAC fuse or 

circuit breaker trips

Shorts or loose connections

Check the wiring connections of the 24 VAC circuit.

Faulty circuit board

Replace the circuit board.

Unit ON, humidifier will 

not operate

Humidifier not receiving power

Verify that RUN/DRAIN switch is in the RUN position.
Check fuses or CBs and replace or reset if necessary.
Make sure molex connector is securely plugged into 

circuit board and that no wires art loose.

Contactor pulled in, but 

no water enters 

canister

No water available to unit

Check external shut-off valves.

Clogged fill line strainer

Clean or replace fill line strainer.

Wiring breaks or loose connections

Check for faulty wiring and loose connections.

Faulty circuit board

Replace circuit board.

Water enters canister, 

but canister full circuit 

activates at a low water 

level

Foaming

Check drain valve and water supply.

Water enters canister, 

but canister full circuit 

activates at a low water 

level

Canister interface connections 

incorrect

Check connection on component plate in humidifier 

cabinet Terminal #1 on the square block interface 

device must be connected to L2 of the power terminal 

block. L2 must also be connected to the electrode 

closest to the steam outlet port.

Verify that the red wire from terminal #2 on the 

interface connects to the red top terminal on the 

canister. This is the one farthest from the steam outlet 

port and is the high water sensor probe. 

Full isolation has broken down

Remove red canister full wire from canister. If normal 

operation resumes, canister must be replaced. 

Remove the wire from terminal #3 on the interface. If 

normal operation resumes, canister full interface must 

be replaced.

Drain assembly not operating freely

Check and replace coil or valve if necessary.

Faulty circuit board

Replace circuit board

Canister fills but 

overflows

Canister full circuit does not activate

Check wiring of canister full interface. Replace circuit 

board.

Humidifier contactor is 

not pulled in (to reset, 

de-energize control 

unit)

Cylinder full. Interface activated.

See similar symptoms above. Canister expired. 

Replace canister.

Problem with fill water system

Water supply is not on. Fill valve problem. Drain valve 

stuck open.

Red LED on humidifier 

control board is on. 

Humidifier contactor not 

pulled in (to reset, de-

energize control circuit)

Humidifier amps reached 138% of full 

load

Canister expired. Replace canister. DIP switch 

settings changed with water in canister. Drain canister, 

call Liebert service.

Humidifier fill valve stuck open; check valve. Water 

conductivity too high; check water conductivity/quality. 

Contact Liebert service.

DIP switches set incorrectly. Refer to Circuit Board 

Mineral deposits obstruct drain valve

Check drain valve for obstructions and clean if 

necessary.

Faulty solenoid

Check for magnetic field at coil.

Faulty circuit board

Replace circuit board.