Herrmidifier Herrmidicool - Manual (Page 3)

Herrmidicool IOS Manual
I n s t a l l a t i o n , O p e r a t i o n & S e r v i c e M a n u a l
3 www.herrmidifier-hvac.com
When the humidity requirement has been satisfied, the EST-
1250 will turn off the demand signal to the AH-1109, which
will close the water solenoid, modulating water valve and
the air solenoid. Water pressure is bled instantly to drain via
the drain solenoid. Air pressure is relieved slowly through
the atomizing heads. The air will dry the internal portions
of the head maximizing the maintenance interval. An air-
proving switch (included) ensures there is airflow prior to the
humidifier turning “On.”
Types of Control
The Herrmidicool System is available with three (3) types
of control – (1) On/Off, (2) Proportional, and (3) P+I – these
provide “good,” “better,” and “best” control.
1. On/Off – Humidity is sensed by a humidistat that
provides digital (On/Off) input to the humidifier.
Humidity swings above and below the setpoint based
on tolerance and accuracy of the humidistat. Due to the
limited controllability of an On/Off controlled adiabatic
humidifier, this control scheme would only be used in
very specific applications.
2. Proportional – The variation between the control input
signal and the humidity setpoint results in adjustments to
the unit output. Variations will be smaller than with “On/
Off” control and will be within the control band.
3. Proportional + Integral – The P + I control simply evaluates
the actual humidity vs. desired humidity over a period
of time or integration period. The humidity difference, or
offset, is corrected by an offset correction. This correction
shifts the bandwidth up or down to attempt to eliminate
the offset condition. This type of control is standard with
AH-1200 Series Control Cabinets. Included with these
cabinets are two humidity sensors. One for return or
room sensing, the second for supply or limit sensing.
II. Unit Operation
The Herrmidicool system is an in-duct air/water atomization
system designed to introduce atomized water into the
airstream. The AH-1200 Series includes two sensors and
an air proving switch. From the inputs of these controls, the
EST-1250 microprocessor creates a demand signal that is
forwarded to the AH-1109 atomizer control board.
AH-1200 Series Control Cabinet
Systems provided with the AH-1200 Series Cabinet include
two duct (room sensors optional) sensors and an air proving
switch. One duct sensor, the “control,” monitors the return air
relative humidity. The other duct sensor, the “limit,” monitors
the relative humidity downstream of the humidifier.
The EST-1250 Control Board compares the two sensor
inputs to the corresponding user selected control setpoints. If
both humidity readings are below their respective setpoints,
the controller will select the value closest to its setpoint and
determine an appropriate demand signal based on that.
The demand signal is fed from the EST-1250 controller to the
AH-1109 atomizing control board.
Once it receives a demand signal from the EST-1250
controller, the AH-1109 will energize the air solenoid. A
pressure switch on the air control section will verify sufficient
air pressure, then the water solenoid will be energized and
the modulating water valve will open to the appropriate level
as dictated by the demand signal.
As the demand signal varies up and down, the modulating
water valve will open and close accordingly. The air pressure
will remain constant allowing finer droplets to be produced as
the system modulates down and evaporation becomes more
difficult.
Control Cabinet