Armstrong World Industries EHU-704 User Manual

1)  Check unit operation.

2)  Look in drain pan for leaks.
3)  Check steam piping for leaks.
4)  Observe duct low points for signs of poor humidity distribution.
5)  Be sure unit is draining freely by pushing the manual drain 

button (the manual tank off button should not be depressed).

1)  Repeat the 5 steps outlined above.
2)  Clean, repair, or replace steam generator.

General:
The steam generator is basically the only part of the EHU that requires regular maintenance. This
maintenance may include cleaning or replacing the tank itself or the electrodes. We recommend sub-
stituting a spare generator in order to minimize downtime and labor requirements. The replaced gener-
ator may then be serviced when it is convenient.

Tank Cleaning:
As the water in the steam generator boils away, the minerals in that water come out of suspension and
are deposited on the walls of the tank and on the electrodes. This process leaves the tank walls coat-
ed with a white or light brown colored mineral buildup. This buildup may be anywhere from soft and
chalky to rock hard. The automatic drain cycle will minimize mineral buildup but, eventually, the tank
will need cleaning.

Tank cleaning is indicated when:
a)  The unit has been in service for a period of time, a solids buildup is visible through the tank 

walls, and the "normal" water level in the tank is rising, or;

b)  The tank cleaning message (C02) is displayed.

Tank replacement is indicated if the tank body becomes deformed in any way, as this could 
cause leakage around the o-ring.

Electrode disintegration generally starts due to high conductivity water being present in the 
steam generator. Electrode disintegration sometimes occurs as a result of a combination of the 
following factors:

a)  High voltage (especially 480 and 600 volts);
b)  Hard water (in excess of 20 grains/gal.);
c)  Any unit with a malfunctioning drain system;
d)  Softened water.

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