ROTRONIC HF3 - Manual (Page 19)

E-M-HF3-V1_22
Rotronic AG
Bassersdorf, Switzerland
Document code Unit
HygroFlex HF3 Transmitters and Thermo-
hygrostats: User Guide Instruction Manual
Document Type
Page 19 of 27
Document title
© 2009-2011; Rotronic AG E-M-HF3-V1_22
7.2 HF34 thermo-hygrostat
7.2.1 Relay operating diagram
Relay 1
Relay 2
7.2.2 Set point adjustment procedure
Two different procedures can be used to adjust each set point. Both require connecting the HF34 to a PC with
the ROTRONIC HW4 software running.
Note:
Adjustment of the set point is by means of a surface mount potentiometer. The scale corresponding to the
minimum and maximum positions of the potentiometer can be changed with the ROTRONIC HW4 software.
Precise adjustment of the set point with the potentiometer is made easier when using a narrow scale. Using
the example of 50.0 %RH for the set point, it is much easier to precisely adjust the potentiometer at 50.0 %RH
with a scale of 49 to 51 %RH than it is with a scale of 0 to 100 %RH. It should be noted that a scale of 49 to
51 %RH does limit any future set point adjustment in the field to only ± 1.0 %RH.
Relay is energized above the set-point:
Common and Normally Open contacts
are connected (use for Dryer) Relay is not energized below the set-point:
Common and Normally Closed contacts
are connected (use for Humidifier)
Set Point
Dead Band
%RH or dew point
Relay is energized above the set-point:
Common and Normally Open contacts
are connected (use for cooling element)
Relay is not energized below the set-point:
Common and Normally Closed contacts
are connected (use for heating element)
Set Point
Dead Band
Temperature