Armstrong World Industries EHU-703 - Manual (Page 19)

Monitoring Current:
While the unit is filling, the current should increase. As the current approaches the maximum rating of
the unit, it increases more slowly, especially in higher capacity units. With the tank on, and the fill and
drain circuits idle, the current should fall slowly. When the unit is draining, the current should decrease
at a moderate rate.
Monitoring % Power:
The percentage power equates to the percentage of maximum steam output. The percentage power
reading will increase and decrease proportionally to the current draw. Overcurrent protection circuitry
starts initiating drain cycles as the % power reading approaches 110%. The overcurrent failure routine
is initiated at about 120%.
Automatic Drain Operation:
The microcontroller will energize the drain valve at the beginning of the fill cycle to reduce the conduc-
tivity and mineral build-up in the tank. It will vary in drain duration to adjust for changes in water quali-
ty, demand history, and steam output.
Manual Drain Mode:
If the manual drain button is pushed while the tank circuit is energized, the fill valve will also open to
temper the drain water. If the tank is off, only the drain valve will open.
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