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ULTRA-SORB MODEL XV INSTALLATION, OPERATION, AND MAINTENANCE MANUAL
3. Humidification demand is provided by a control signal to the DriSteem
control cabinet. When the demand signal is sufficient, steam will flow to
1) the internal heat exchanger and 2) the modulating control valve that
provides steam output based on demand.
4. As the 2-position shutoff valve opens (approx. 75 seconds), the heat
exchanger in the steam dispersion panel begins operating. The heat
exchanger will continue to operate any time there is duct air flow and
humidification demand.
5. The shutoff valve actuator includes an end switch that enables the
modulating control valve if the shutoff valve is over 90% open. The end
switch of the shutoff valve actuator is wired to an input of the steam
dispersion panel controller. If the input is not made, the modulating control
valve will remain closed.
6. If the shutoff valve does not reach 90% open after 4 minutes (determined
by actuator end switch), the steam dispersion panel controller will close the
shutoff valve and activate a failure alarm contact on the control board, and
provide LED alarm indication on the controller. See Figure 21 [DriSteem
alarm point to be wired to BAS as specified.]
7. When the steam dispersion panel controller verifies the shutoff valve is
open, it allows the modulating control valve to modulate based on the
control signal, providing a 2-10 VDC signal from the control board to the
valve actuator. At low/no demand signal or space RH above setpoint and
outside the PID band, the valve is closed. At high demand or space RH
below setpoint, the valve opens. Modulating control valve is spring-return
to fail to the closed position.
8. When the air handling unit fan stops (Unoccupied Mode by command
of BAS, or other means) the air flow input wired to the steam dispersion
panel controller opens, and controller returns the modulating control valve
to the closed position.
9. After the modulating control valve is closed, the 2-position shutoff valve
remains open, to maintain steam flow through the heat exchanger for 15
minutes to evaporate any remaining condensate in the steam dispersion
panel header.
Sequence of operation
OPERATION
