Specifications

Page 46 • DRI-STEEM XT Electrode Steam Humidifier Installation, Operation, and Maintenance Manual
Operation
Principle of operation
1. Controller receives a call for humidity
When the RH level in the humidified space drops below set
point, the humidifier controller receives a call for humidity and
calculates a corresponding electrical current. The controller
closes the contactor, which energizes the electrodes. If there is
not enough water in the steam cylinder, the fill valve opens and
water enters the steam cylinder.
2. Energized electrodes boil water into steam
When the water level in the steam cylinder rises to touch the
electrodes, electrical current flows through the water between
the electrodes. Electrical resistance in the water causes the
water to heat up and boil into steam. The steam flows through
the steam outlet and through steam hose, tubing, or piping to
the XTSB or dispersion assembly, where it is discharged into
the airstream.
3. Electrical current increases to meet demand
As the amount of water covering the electrodes increases,
current flow increases. The fill valve remains open until
the amperage increases to 10 percent above the current
corresponding to the demand signal. Then the fill valve closes,
and the water boils into steam.
4. Water continues to boil into steam
As the water boils into steam, the amount of water covering the
electrodes decreases, and current flow decreases. When current
flow decreases to 10 percent below the current corresponding
to the demand signal, the fill valve opens to increase the water
level in the steam cylinder, which increases current flow and
steam production.
5. Controller initiates drain/fill events to flush conductive ions
As steam production continues, the concentration of
conductive ions in the water increases, eventually leading to
increased electrical current through the water. An algorithm
monitors water conductivity and auto tunes drain and fill
events to keep electrical current within demand parameters.
This optimizes humidifier performance based on water
conditions and steam production.
The humidifier has integral drain water tempering. Drain water
is automatically cooled before entering the drain.
mc_091010_1415
Figure 46-1:
XT humidifier principle of operation
OM-7641X
mc_111610_0455
1
4
3
2
5
(drain)
5
(fill)
Staging multiple XT humidifiers
Up to four XT humidifiers can be staged
to operate in sequence. In a sequenced
application, one control input signal is divided
into user-selectable control input signals for the
connected humidifiers. See the
Vapor-logic4
Installation and Operation Manual
for
instructions on staging multiple XT humidifiers.