CSZ EZT-570i, Technical Manual

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EZT-570i Technical Manual
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4.2 Humidity System
When the humidity system is enabled, the humidity system output (Q32) will turn on. This turns on
water supply solenoids and atomizer air compressor if applicable. If the refrigeration system is set to
run in single stage mode when humidity is on, system 2 compressor (Q4) will then be turned off as
long as humidity is on. The maximum humidify output (Q33) will turn on whenever the humidification
output percentage exceeds the set point in the configurator for the on delay time period.
An alarm delay is added to the boiler low water input (I7) in order to allow enough time for it to fill with
water when the humidity system is first turned on. The delay will prevent the alarm from going off for
a period of 30 minutes. Should the level not be made in that time, the alarm will sound and shut
down the chamber. Once the proper water level is reached, the alarm will sound and shut down the
chamber immediately upon loosing the input. Should the alarm occur, silence the alarm from the
alarm monitor screen and the chamber will begin operating again and restart the 30 minute alarm
delay timer.
Temperature Limits
The EZT limits the humidity system’s operational range to a minimum and maximum temperature as
set in the configurator. These limits are typically set around freezing and boiling temperatures. Once
the air temperature exceeds either limit, the EZT shuts down the humidity system automatically. If
the humidity system is shut down due to temperature limitations, the system status monitor will
indicate that this has occurred by illuminating the “RH TMP DISABLE” indicator. The humidity system
will restart automatically once the air temperature returns to within the set temperature range.
Dewpoint Limits
In order to protect the refrigeration system and chamber from damage, there are minimum and
maximum dewpoint levels that are set in the configurator. These limits in turn define the minimum
and maximum relative humidity levels that the chamber will operate to at any given temperature. The
EZT uses these limits and internally calculates the minimum and maximum humidity level that the
chamber will control to at the current chamber temperature.
Should the user enter a set point outside of those limits, the EZT will coerce the 9300 set point to the
minimum or maximum value allowed. The system status monitor will then indicate that limiting is
taking place and in which direction by illuminating the appropriate LED on the system status monitor
screen.
Low RH (Frozen Coil)
For chambers equipped with the low RH (frozen coil) option, the EZT monitors the temperature and
relative humidity set points and calculates the resulting dewpoint. When this value is below the
standard wet coil range of 2°C (35°F), the EZT automatically switches to frozen coil mode. This
allows the chamber to reach lower humidity levels than what is capable with standard humidity. The
EZT does not initiate frozen coil mode until the measured dewpoint in the chamber is below 10°C
(50°F). This prevents the coil from loading up with moisture prematurely and reducing the duration of
time at which the coil can affectively control low humidity levels in the chamber.
When frozen coil mode is initiated, the frozen coil control output (Q35) turns on. This activates the
EPR bypass solenoid and transfers control from the wet coil solenoid to the frozen coil solenoid to the
dehumidification output of the 9300 controller.