User Manual THR842DUK Wireless Digital Thermostat 50051983-001 Rev.
homexperttm by Honeywell THR842DUK Wireless Digital Thermostat Contents WARNING: This product must be correctly installed and configured to work properly (see pages 12-23). If you are not experienced in wiring electrical equipment, we recommend professional installation to avoid possible personal injury or equipment damage. TIP: After installation, see the QUICK START GUIDE on page 6 to customise and begin using your new thermostat right away.
User Manual homexperttm by Honeywell THR842DUK Wireless Digital Thermostat What is a room thermostat? ...an explanation for householders A room thermostat simply switches the heating system on and off as necessary. It works by sensing the air temperature, switching on the heating when the air temperature falls below the thermostat setting, and switching it off once this set temperature has been reached. Turning a room thermostat to a higher setting will not make the room heat up any faster.
User Manual homexperttm by Honeywell THR842DUK Wireless Digital Thermostat About your new wireless thermostat Quick reference The THR842DUK is an easy-to-use thermostat designed to maintain a comfortable environment when you are at home and reduce energy costs when you are away. One touch of the ECO button overrides the normal temperature to maintain a lower, energy-saving level for a specified period of time (see page 11).
Operation homexperttm by Honeywell THR842DUK Wireless Digital Thermostat On/off switch and frost protection 25.0 °c Heating or cooling control Press and hold the ON/OFF button as shown at left to turn the thermostat on or off. When off, the thermostat will never activate the cooling system, and will activate heating only if necessary to maintain a minimum indoor temperature of 5º C (frost protection).
Operation homexperttm by Honeywell THR842DUK Wireless Digital Thermostat Temperature control When idle, the thermostat displays the current room temperature. You can press the p or q buttons at any time to see the “target” temperature the thermostat is trying to maintain. Current room temperature 24.0 °c Press buttons to display or change target temperature 25.0 Energy-saving ECO mode One button press will display the target temperature, flashing.
Installation and Setup homexperttm by Honeywell THR842DUK Wireless Digital Thermostat System installation Install relay box Installation procedure The relay box is wired directly to your heating or cooling equipment. The thermostat communicates with the relay box using a wireless RF signal to control the system. Do not install near metal objects or electronic devices (TV, sound system, PC, etc.).
Installation and Setup homexperttm by Honeywell THR842DUK Wireless Digital Thermostat Connect system wiring Wiring diagrams Connect wiring from your heating or cooling equipment to the relay box as shown at left. See wiring diagrams on page 15 for details. Burner (direct control) Combi boiler Zone valve Cooling device 1 Make sure electrical power is off. 2 Strip insulation to expose about 6 mm of bare wire. 3 Use a screwdriver to loosen terminal screw, insert wire into slot, then tighten screw.
Installation and Setup homexperttm by Honeywell THR842DUK Wireless Digital Thermostat Activate batteries and test thermostat Test thermostat (continued from page 16) Grasp and pull to remove the thermostat cover. Discard the plastic tab inside to activate the batteries, then test as shown below. NOTE: This symbol will flash on the screen when battery power is low. Remove cover and replace batteries with two fresh AA alkaline batteries. Remove tab 5.
Installation and Setup homexperttm by Honeywell THR842DUK Wireless Digital Thermostat Test thermostat location (continued from page 17) Press and hold again Check wireless signal strength Test signal strength to find a suitable location for the thermostat before installation. EEse 55 Install thermostat The wireless thermostat can be mounted in the table stand, or on a wall.
Installation and Setup homexperttm by Honeywell THR842DUK Wireless Digital Thermostat System test Installer setup After installation, you should check to make sure the system is working properly. Set temperature to maximum 35.0 °c 2 Press the p button to raise target temperature to maximum (35°C). If the system is set up properly, the “heating” symbol should appear on the thermostat display, the heating system should begin running, and the green light on the relay box should be on.
Installation and Setup homexperttm by Honeywell THR842DUK Wireless Digital Thermostat Installer setup functions Installer setup functions ** Factory default setting Function Description Setting Options 1: Ot Minimum boiler on/off time 1 minute ** Options: 1 to 5 minutes See page 24 for important information 2: Cr Cycles per hour (CPH) 6 cycles per hour ** Options: 3, 6, 9 or 12 See page 24 for important information 3: Pb Proportional band width 1.5°C ** Options: 1.
Installation and Setup homexperttm by Honeywell THR842DUK Wireless Digital Thermostat Customised settings for your system Your heating system Description of functions Changes required Setting Options Standard gas boiler (<30kW) None No change Zone Valve None No change Oil boiler Function 1: Ot Function 2: Cr Set to 4 minutes Set to 3 CPH Thermal actuator Function 2: Cr Set to 12 CPH Electric heating Function 2: Cr Set to 12 CPH Your cooling system Changes required Setting Options Hea
Appendix homexperttm by Honeywell THR842DUK Wireless Digital Thermostat In case of difficulty In case of difficulty Thermostat screen is blank • Make sure two fresh AA alkaline batteries are properly installed (see page 16). Heating or cooling system does not respond • Check thermostat batteries (see above). • Make sure heating and cooling systems have power. Check fuses and circuit breakers and replace or reset as needed.
Appendix homexperttm by Honeywell THR842DUK Wireless Digital Thermostat Re-binding procedure Re-binding procedure (continued from page 28) If you must replace a wireless thermostat or relay box, the system will not work until both devices can communicate with each other. This is called binding. Follow the steps below to re-establish wireless communication. 1 Hold thermostat about 1 or 2 metres from the relay box, then press and hold the relay button for 15 seconds.
Appendix homexperttm by Honeywell THR842DUK Wireless Digital Thermostat Limited Warranty Declarations, disposal and recycling Honeywell warrants this product for 1 year from date of purchase. We undertake to replace or repair at our discretion, products should they become defective within 1 year solely as a result of faulty materials and or workmanship.
Need Help? For assistance with this product please visit www.homexpertbyhoneywell.com, or call Honeywell Customer Care at 0845 604 2893. ® Honeywell The Arnold Centre Paycocke Road Basildon, Essex SS14 3EA Technical Help Desk: 0845 604 2893 50051983-001 Rev. A www.homexpertbyhoneywell.
