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The transmitter requires 24 VDC. The sensor provides an accurate and predictable four-wire, 4-20 mA output signal for temperature and a second 4-20 mA output signal for humidity. Dimensions FRONT 0.95" (241mm) 2.25" (572mm) 2.75" (699mm) 0.75" (191mm) VIEW SIDE VIEW 4.5" (1143mm) Wall TOP VIEW Specifications Output 4 to 20 mA Sensor 10K . platinum RTD Supply Voltage 24 VDC Tolerance of Resistance (Accuracy) ±1.5°F (±0.83°C) ±2% RH (from 15 to 95% RH) Response Time 20 seconds for a 63% step Environmental Operating Range (Transmitter) 45°F to 96°F; 0 to 100% RH (7°C to 35°C); 0 to 100% RH Termination The THW420 transmitter must be powered from a 24 VDC supply. The combination temperature/ humidity sensor is terminated as follows: .The humidity transmitter requires a three-wire termination for the 4-20mA output using 24 VDC. .The temperature sensor also requires a three- wire termination. In most cases, it obtains power from the analog input to which it is connected and no external power is required. Though interference from external sources is not a major problem with current transmitters, Liebert recommends separating the wiring from line voltage wiring and from wiring used to supply highly inductive loads such as motors, generators and coils. Liebert also recommends making power connections with twisted pair wire of at least 22 AWG and crimp- type connectors. Ground 4-20 mA Input #1 + - 4-20 mA Input #2 + - X U3 Terminations +24VDC should be used at all times SW2 OUTPUT SELECT ON 0-5V 0-5V 0-5V RUN RESIST. 4-20ma 4-20ma Ch1 CAL SW2 C9 GndV+Ch1Ch2 J2 J3 DISPLAY CYCLE IN SECONDS 10 3 T POT1 20 H The GND (common)between the Power Ch3CALTempTemp R19T&B SWITCH Short Norm Open SW1 RTH1 RTH2 J1 Building AutomationProducts, Inc. Copyright 2000REV. 101600 XCOMBO T&B Controller To GND (common) of controller* From +24VDC of controller or power supply To controller.s analog input (humidity signal, 4-20mA) To controller.s analog input(temperature signal, 4-20mA) * NOTE: and Sensor %RH Ch3 Ch2 terminal is common ! CAUTION Liebert recommends wiring the sensor WITHOUT power applied because accidental arcing may damage the product and will void the warranty. Ordering Information Quantity Part # THW420 Description Combination Temperature/Humidity Transmitter Wall 4-20 mA @ 45°F to 96°F and 0 to 100% RH SL-31080 Product Specification/Installation Sheet page 1 6/03 (Rev. 0) Mounting Enclosure Mounting Instructions Mounting hardware is provided for both junction box and drywall installation. 1. Pull the wires through the opening in the base plate. 2. For junction box installation: Secure the base to the box using the #6-32 x 1/2" mounting screws provided. For drywall installation: Drill two 3/16" holes 3-1/4" apart on center. Insert the drywall anchors and secure the base using the #6 x 1" sheet metal screws provided. 3. Terminate the unit according to the guidelines in Termination on page 1. 4. Attach the cover by latching it to the top of the base, rotating the cover down and snapping it into place. 5. Secure the cover by backing out the lock-down screws using a 1/16" allen wrench until they are flush with the bottom of the cover. NOTE In a wall-mount application, the wall temperature and the temperature of the air within the wall cavity can cause erroneous readings. The mixing of room air and air from within the wall cavity can lead to condensation and premature failure of the sensor. To prevent these conditions, seal the conduit leading to the junction box and seal the hole in the drywall by using an adhesive backed, foam insulating pad. Troubleshooting Guide The following table lists common problems and possible solutions. For more information, consult your local dealer, Liebert representative or the Liebert Worldwide Support Group. Junction box 2" x 4" Mounting screws Cover Delta base Wall Locking screws Problems Possible Solutions Unit will not operate . Check +24 VDC power supply at controller. . Disconnect the sensor and check power wires for +24 VDC. Humidity reading is maximum 20 mA or 100% . Make sure the sensor is installed properly, and is not shorted. . Quick Check: Remove the sensor. If the reading does not change, contact technical support. Humidity reading is minimum 4 mA or 0% . Verify that the humidity sensor installed. . Quick Check: Short the sensor terminal block with a wire. Does the reading change? If so, the sensor may be faulty; if not, contact technical support. Humidity reading in software appears to be off more than specified accuracy . Check all software parameters. . If available, check the sensor against a calibrated control such as a hygrometer. . Determine if the sensor is exposed to an external source more than room. Temperature sensor in front- end software is reading high . Make sure wiring is correct. . Disconnect wires and measure with a multimeter. Temperature sensor in front- end software is reading low . Make sure wiring is correct. . Disconnect wires and measure with a multimeter. SL-...