Copyright HK Instruments 2021
www.hkinstruments.fi
Installation version 7.0 2021
INSTALLATION
INSTRUCTIONS
HUMIDITY TRANSMITTERS
RHT-MOD Duct Series
• READ THESE INSTRUCTIONS CAREFULLY BEFORE
ATTEMPTING TO INSTALL, OPERATE OR SERVICE THIS
DEVICE.
• Failure to observe safety information and comply with
instructions can result in PERSONAL INJURY, DEATH AND/OR
PROPERTY DAMAGE.
• To avoid electrical shock or damage to equipment, disconnect
power before installing or servicing and use only wiring with
insulation rated for full device operating voltage.
• To avoid potential fire and/or explosion do not use in potentially
flammable or explosive atmospheres.
• Retain these instructions for future reference.
• This product, when installed, will be part of an engineered
system whose specifications and performance characteristics
are not designed or controlled by HK Instruments. Review
applications and national and local codes to assure that the
installation will be functional and safe. Use only experienced and
knowledgeable technicians to install this device.
SPECIFICATIONS
Thank you for choosing an HK Instruments RHT-MOD Duct se-
ries relative humidity transmitter with Modbus interface. The RHT
-MOD Duct series is intended for use in commercial environments
in HVAC/R applications.
RHT-MOD Duct is a relative humidity transmitter with temperature
output installed in air ventilation duct. In addition to these measured
values, RHT-MOD Duct calculates various parameters such as dew
point, mixing ratio, enthalpy and absolute humidity. Illuminated dis-
play ensures easy readability also from a distance. The RHT-MOD
Duct has a screwless lid and an easily adjustable mounting flange
that make the installation of the device easy.
RHT-MOD Duct series devices are commonly used to monitor and
control:
• Relative humidity and temperature levels of incoming and return air
in ventilation system
SPECIFICATIONS
Performance
Measurement ranges:
Temperature: -30...80 °C, sensor
Relative humidity: 0–100 %
Accuracy:
Temperature: <0.5 ºC
Relative humidity: ±2...3 % at 0...50 °C and 10–90 % rH
Total error band includes accuracy, hysteresis and
temperature effect over 5...50 °C and 10–90% rH.
Technical Specifications
Media compatibility:
Dry air or non-aggressive gases
Measuring units:
°C and % rH
Measuring element:
Temperature: NTC10k
Relative humidity: Thermoset polymer capacitive
sensing element
Environment:
Operating temperature: 0...50 °C
Storage temperature: -20...70 °C
Humidity: 0 to 95 % rH, non condensing
Physical
Dimensions:
Case: 119 x 95.5 x 45 mm
Probe: L=188 mm, d=12 mm
Mounting:
With flange, adjustable 40...155 mm
Weight:
150 g
Materials:
Case: ABS
Cover: PC
Probe: ABS
Mounting flange: LLPDP
Protection standard:
IP54
Electrical connections:
4 spring loaded terminals
Power supply:
(24 V and GND)
0.2–1.5 mm
2
(16–24 AWG)
Modbus RTU:
A and B line
0.2–1.5 mm
2
(16–24 AWG)
Electrical
Supply voltage: 24 VAC or VDC ±10 %
Current consumption: max 90 mA (at 24 V) + 10 mA for
each voltage output
Communication
Protocol: MODBUS over Serial Line
Transmission Mode: RTU
Interface: RS485
Byte format (11 bits) in RTU mode:
Coding System: 8-bit binary
Bits per Byte:
1 start bit
8 data bits, least significant bit sent
first
1 bit for parity
1 stop bit
Baud rate: selectable in configuration
Modbus address: 1−247 addresses selectable in
configuration menu
Conformance
Meets the requirements for:
CE:
UKCA:
EMC:
2014/30/EU
S.I. 2016/1091
RoHS:
2011/65/EU
S.I. 2012/3032
WEEE:
2012/19/EU
S.I. 2013/3113
INTRODUCTION
WARNING
APPLICATIONS
RoHS
COMPLIANT
