STULZ Ultra-Series Humidifier Controller
(August, 2013)
19
input is provided as a standard and up to two additional
customer alarm inputs may be enabled as an option.
4.5.1.4 Air Flow Proving (DAH option)
When the Airflow proving switch detects an insufficient air
flow condition, the system controller will display a "Loss of
Air Flow" alarm and shut down the Humidifier(s). When the
Airflow problem is corrected and the alarm is re-set, the
Humidifier(s) will automatically resume operation.
4.5.1.5 Air
Velocity
Monitoring (DAH option)
The Humidifier outlet air velocity may be monitored by a
sensor. If enabled, the controller provides a display screen
with the current air velocity. An air velocity alarm will be
triggered if the velocity falls outside a selectable minimum
and maximum range.
4.5.1.6 Low Temperature Limiting (Optional)
The Humidifier return air temperature may be monitored by
a sensor. As the low air temperature threshold is
approached, the controller linearly limits the humidification
signal. If the return air temperature drops below a
selectable threshold temperature, a low temperature alarm
will be signaled. The controller is programmed to shut down
the Humidifier and drain the reservoir upon sensing a low
temperature alarm to prevent damage due to freezing.
4.5.1.7 Cabinet
Temperature Monitoring
A digital output signal from the controller turns on a cooling
fan located inside the control cabinet when the internal
temperature rises to a threshold plus dead band. If the
enclosure temperature continues to rise, the controller
activates a high temperature alarm and stops Humidifier
operation. The "Fan On" set point and "High Cabinet
Temperature Alarm" threshold are adjustable in the
Control>Alarm Set menu loop (see Section 5.4.2).
4.5.1.8 Water
Conductivity
Monitoring
A sensor installed in the water supply piping permits
monitoring the water conductivity as a measure of
determining when the mineral content is too high. This will
ensure clean, mineral free mist production. The supply
water quality specified for STULZ Ultrasonic
Humidifiers during normal operation should not exceed 5
microSeimens. The controller will provide a pre-alarm
message if this water conductivity rises above 5
microSeimens for more than 5 minutes. If water conductivity
rises above 20 microSeimens for more than 5 minutes, the
controller will shut down the Humidifier(s) and provide a full
alarm text message and indicate a summary alarm
condition, energizing the N.O./N.C. summary alarm
contacts, and optional audible alarm.
4.5.1.9 Water Leak Detection (Optional)
The Humidifier controller may monitor water leaks via
optional water detector(s). Refer to Section 2.6.6. Upon
sensing a water leak, the controller activates the summary
alarm logic and displays a "Water" alarm message. The
controller recognizes a water alarm as a Critical Alarm and
shuts down Humidifier operation.
Remote On/Off
4.5.2
For Remote On/Off operation, terminal positions are
provided to connect a remotely located, On/Off switching
control device. If the Humidifier is turned on and the Ultra
series controller receives a remote input signal to turn off
the Humidifier, the controller disables all control outputs and
a message "Off by Remote Shutdown" appears in the main
display screen. The system will automatically be re-enabled
when the remote On/Off signal calls for the Humidifier unit
to turn back on.
The control device may be an On/Off switch, thermostat or
a humidistat. If customer provided, the remote On/Off
control contacts must be sized appropriately. The Remote
On/Off contacts must have a minimal rating of 24 VAC.
Refer to the electrical drawing included with the unit for the
electrical specifications and for wiring details.
Automatic Drain Cycle
4.5.3
The controller is configured to activate a drain cycle of the
Humidifier reservoir(s) during periods of inactivity. This
ensures a fresh supply of water in the reservoir. If the total
demand for humidity production has been below 10% for
the time interval for the drain cycle is programmed (Default
of 72 hours, the humidifiers will be commanded to drain.
The idle time and drain duration may be adjusted in the
Service menu (see Section 5.5.1.2). When a drain cycle is
initiated due to the idle time elapsing, the following occurs:
1. Humidification stops.
2. The drain valve is energized open.
3. At the end of the drain duration time, the drain valve
closes.
4. When a demand is present, the fill valve opens and
humidification returns to normal.
The water reservoir is emptied entirely during the auto drain
cycle. If there is a demand for humidification, the drain cycle
is interrupted. The drain valve closes and the fill valve
opens. When the water level in the reservoir is at an
appropriate level, the unit begins producing humidity.
Manual Drain
4.5.4
The operator may manually drain the reservoir of an
individual Humidifier by energizing its drain solenoid valve.
This is accomplished with the controller by accessing the
Manual Control screen from the Service>Humid menu loop
(see Section 5.5.1.14).
