Honeywell THR840DUK Thermostat User Manual

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User Manual  
THR840DUK  
Digital Thermostat  
5
0051982-001 Rev. A  
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homexpert by Honeywell THR840DUK Digital Thermostat  
Contents  
About your new thermostat  
Appendix  
What is a room thermostat? ..................4-5  
QUICK START GUIDE.............................6  
Quick reference to controls.......................7  
In case of difficulty..................................25  
Warranty information...............................26  
Disposal & recycling................................27  
WARNING: This product must be correctly installed and configured to work properly (see  
pages 12-24). If you are not experienced in wiring electrical equipment, we recommend  
professional installation to avoid possible personal injury or equipment damage.  
Operation  
NOTE: This symbol will flash on the screen  
when battery power is low. Remove cover and  
replace batteries with two fresh AA alkaline  
batteries as shown on page 18.  
On/off switch............................................8  
Heating or cooling control.........................9  
Temperature control................................10  
Energy-saving ECO mode ......................11  
TIP: After installation, see the QUICK START GUIDE on page 6 to customise and begin using  
your new thermostat right away.  
Installation and setup  
System installation..................................12  
Wall bracket installation ..........................13  
System wiring....................................14-17  
Battery installation & mounting................18  
System test ............................................19  
Installer setup ....................................20-24  
Copyright © 2010 Honeywell International Inc.  
homexpert by Honeywell is a trademark of Honeywell International Inc. All rights reserved.  
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User Manual  
homexpert by Honeywell THR840DUK Digital Thermostat  
What is a room thermostat?  
.
..an explanation for householders  
If your heating system is a boiler with radiators, there will usually be only one room thermostat to control the  
whole house. But you can have different temperatures in individual rooms by installing thermostatic radiator  
valves (TRVs) on individual radiators. If you don’t have TRVs, you should choose a temperature that is  
reasonable for the whole house. If you do have TRVs, you can choose a slightly higher setting to make sure  
that even the coldest room is comfortable, then prevent any overheating in other rooms by adjusting the TRVs.  
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. How quickly the room heats up depends on the design of the heating system,  
for example, the size of boiler and radiators.  
Room thermostats need a free flow of air to sense the temperature, so they must not be covered by curtains  
or blocked by furniture. Nearby electric fires, televisions, wall or table lamps may prevent the thermostat from  
working properly.  
Neither does the setting affect how quickly the room cools down. Turning a room thermostat to a lower setting  
will result in the room being controlled at a lower temperature, and saves energy.  
The heating system will not work if a time switch or programmer has switched it off.  
The way to set and use your room thermostat is to find the lowest temperature setting that you are  
comfortable with, and then leave it alone to do its job. The best way to do this is to set the room thermostat  
to a low temperature – say 18°C – and then turn it up by one degree each day until you are comfortable with  
the temperature. You won’t have to adjust the thermostat further. Any adjustment above this setting will waste  
energy and cost you more money.  
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User Manual  
homexpert by Honeywell THR840DUK Digital Thermostat  
About your new thermostat  
Quick reference  
The THR840DUK 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).  
Cooling system is  
running (see page 9)  
ECO mode countdown  
(see page 11)  
Heating system is  
running (see page 9)  
Press to change  
temperature  
(see page 10)  
ECO mode is on  
see page 11)  
Press to turn ECO mode  
on or off (see page 11)  
(
eco  
QUICK START GUIDE  
Press to turn thermostat  
on or off (see page 8)  
Appears when  
target temperature  
is showing  
°c  
25.0  
Your new thermostat is pre-programmed and ready to go. Just check the steps below and change  
settings if needed:  
1
Install and set up thermostat  
if this has not been done by a professional installer).......................................................... See pages 12-24  
(
Current temperature  
(or target temperature  
when flashing)  
2
3
Select heating (default) or cooling mode..................................................................................... See page 9  
Set desired indoor temperature................................................................................................ See page 10  
System fault  
see page 25)  
Low battery warning  
(see page 18 to replace  
batteries)  
Standby symbol  
(
appears when  
thermostat is off (see  
page 8)  
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Operation  
homexpert by Honeywell THR840DUK Digital Thermostat  
On/off switch and frost protection  
Heating or cooling control  
Press the ON/OFF button as shown at left to turn the thermostat on  
Press and hold both buttons for 5 seconds  
The thermostat is pre-set to control only your heating system. If  
installed and set up correctly, it can also be used to control your  
cooling system.  
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).  
°
c
To switch between heating and cooling, press and hold the p and q  
buttons together until the screen changes.  
25.0  
°
25.0  
Heating changes to cooling  
c
You can change the frost protection temperature to any level between  
5
º and 16º C, or turn this feature off so the heating system is never  
activated when the thermostat is off (see page 22).  
NOTE: The thermostat will not switch to cooling control unless you  
enable this feature (see page 22).  
Press and hold  
to turn on or off  
NOTE: When you change the system, the “Heating” and “Cooling”  
symbols will appear for a few seconds, then disappear. Normally, these  
symbols appear only when the heating or cooling system is running.  
°
c
°c  
5
Symbol appears when  
.
0
25.0  
System maintains  
minimum  
thermostat is off  
temperature when  
thermostat is off  
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Operation  
homexpert by Honeywell THR840DUK Digital Thermostat  
Temperature control  
Energy-saving ECO mode  
Current room temperature  
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.  
Press to enter ECO mode  
The ECO mode overrides thermostat settings to maintain a different  
temperature for 1 to 24 hours. This can be useful to reduce heating or  
cooling costs when you are away from home.  
eco  
One button press will display the target temperature, flashing. To  
change it, press either button repeatedly, until the display shows  
the temperature you want. After a few seconds the display will stop  
flashing and change to show the current room temperature.  
1
2
Press the green ECO button to display timer.  
°
24.0  
c
1hr  
Press the p or q buttons to set timer (1-24 hours).  
While in ECO mode, the screen will alternately display remaining time  
and current room temperature. After the timer expires, the thermostat  
will resume normal operation. Options:  
Set number of hours  
NOTE: You can use the ECO mode to temporarily override the target  
temperature for a specified period of time (see page 11).  
Press buttons to display or change target  
temperature  
eco  
•
Press the p or q buttons to raise or lower the temporary ECO  
temperature if needed.  
3
hr  
Change ECO temperature (if needed)  
•
Press the ECO button again to cancel ECO mode and resume  
normal operation.  
°
0
c
2
5.  
NOTE: The default ECO temperature is pre-set to 18º C. To raise or  
lower the default temperature, see page 22.  
eco  
°
c
18.0  
1
0
11  
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Installation and Setup  
homexpert by Honeywell THR840DUK Digital Thermostat  
System installation  
Wall bracket installation  
Installation procedure  
Remove the thermostat cover and use a screwdriver to pry  
open the tabs as shown at left, then remove the thermostat  
from the wall bracket. Install about 1.2 to 1.5 metres above  
the floor, where the display screen can be easily seen.  
1
2
Disconnect electric power  
NO  
NO  
Choose thermostat location and  
install wall bracket  
OK  
•
Do not install near sources of hot or cold air (radiators,  
windows, heating or cooling ducts).  
3
4
Connect system wiring  
Thermostat  
Wall bracket  
Activate batteries and attach  
thermostat cover  
5
6
Restore electric power  
Setup and test system operation  
NOTE: If you are not experienced in equipment installation, we recommend that these  
procedures be done by a professional installer.  
DISCONNECT ELECTRIC POWER BEFORE INSTALLATION: Can cause electrical shock or  
equipment damage.  
1
2
13  
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Installation and Setup  
homexpert by Honeywell THR840DUK Digital Thermostat  
Connect system wiring  
Wiring diagrams  
Connect wiring from your heating or cooling  
equipment to the thermostat as shown at left.  
See wiring diagrams on pages 15-17 for details.  
Basic boiler  
Combi boiler  
1
2
Make sure electrical power is off.  
Strip insulation to expose about 6 mm of  
bare wire.  
3
4
Use a screwdriver to loosen terminal screw,  
insert wire into slot, then tighten screw.  
Replace thermostat cover, then restore  
electrical power.  
NOTE: All wiring must comply with IEE  
regulations. Keep AC mains supply/load cables  
separate from equipment wiring.  
2
.0 - 2.5 mm  
1
6
mm max.  
1
4
15  
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Installation and Setup  
homexpert by Honeywell THR840DUK Digital Thermostat  
Wiring diagrams  
Wiring diagrams  
Zone valve  
(drive open, drive closed)  
Electric resistance  
heater  
Thermal actuator  
Zone valve  
L
N
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Installation and Setup  
homexpert by Honeywell THR840DUK Digital Thermostat  
Activate batteries and mount thermostat  
System test  
Remove the thermostat cover (see page 13). Discard the plastic tab  
inside to activate the batteries, then replace batteries. The thermostat  
should display the current room temperature.  
Set temperature to maximum  
After installation, you should check to make sure the system is  
working properly.  
1
2
Check the power supply to make sure the heating system is on.  
Replace the thermostat front cover, then mount the thermostat on the  
wall bracket as shown at left.  
°
°
c
c
Press the p button to raise target temperature to maximum  
3
5.  
0
(35°C).  
NOTE: This symbol will flash on the screen when battery  
power is low. Remove cover and replace batteries with  
two fresh AA alkaline batteries.  
If the system is set up properly, the “heating” symbol should  
appear on the thermostat display, and the heating system should  
begin running.  
Heat should turn on  
3
To stop the test, press the q button to lower the target  
temperature to an appropriate level. The heating system should  
turn off and the “heating” symbol on the thermostat screen should  
disappear.  
3
5.  
0
1
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Installation and Setup  
homexpert by Honeywell THR840DUK Digital Thermostat  
Installer setup  
Installer setup functions  
** Factory default setting  
Installer settings allow you to customise how your system  
works. Check the tables on pages 21-23 to see if any settings  
need to be changed.  
Function  
Description  
Setting Options  
1: Ot  
Minimum boiler on/off time  
1 minute **  
°
c
Options: 1 to 5 minutes  
See page 23 for important information  
To change installer settings:  
2
Press and hold both buttons for 5 seconds  
5.  
0
1
2
Press and hold the ON/OFF button for 5 seconds.  
2
3
: Cr  
Cycles per hour (CPH)  
6 cycles per hour **  
Options: 3, 6, 9 or 12  
See page 23 for important information  
Press and hold the p and q buttons together until the  
screen changes.  
: Pb  
Proportional band width  
Temperature offset  
1.5°C **  
Options: 1.5° to 3°C  
3
Press the p or q buttons to scroll through functions  
quickly until you find one you want to change (see list on  
pages 21-22).  
i0se  
4: tO  
0: No offset **  
Options: +3° to -3°C  
4
5
To change any setting, press the ON/OFF button, then  
press the p or q buttons until the correct value is flashing.  
5
6
: uL  
: LL  
Maximum temperature allowed  
Minimum temperature allowed  
35°C **  
Options: 21° to 35°C  
Press the ON/OFF button again to save your choice, then  
use the p or q buttons to select another function.  
5°C **  
Options: 5° to 21°C  
0e: 1  
Setting  
To exit installer setup, press and hold the ON/OFF button  
for 5 seconds.  
NOTE: See descriptions of functions on page 24.  
Function  
2
0
21  
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Installation and Setup  
homexpert by Honeywell THR840DUK Digital Thermostat  
Installer setup functions  
Customised settings for your system  
Enter Installer Setup (see page 27), then press p or q for access to system settings  
Function  
Description  
Setting Options  
Your heating system  
Changes required  
Setting Options  
No change  
7
: ES  
ECO default temperature  
18°C **  
Options: 5° to 35°C  
Standard gas boiler  
(<30kW)  
None  
None  
8
: HC  
Heating/Cooling options  
0: No central cooling system installed **  
: Allows switching between heating and cooling systems  
Thermostat cannot control cooling unless you select 1  
Zone Valve  
Oil boiler  
No change  
1
Function 1: Ot  
Function 2: Cr  
Set to 4 minutes  
Set to 3 CPH  
9
1
: OS  
Frost protection temperature  
Electric heat  
5°C **  
Thermal actuator  
Electric heating  
Function 2: Cr  
Set to 12 CPH  
Options: — (none) or 5° to 16°C  
Function 2: Cr  
Function 10: EH  
Set to 12 CPH  
Set to 1 if load > 3A  
0: EH  
0: Resistive loads <3 A **  
1: Resistive loads 3 to 8 A  
See page 23 for important information  
1
1: FS  
RESET TO FACTORY DEFAULT  
0: No change  
Your cooling system  
Changes required  
Setting Options  
1
: Select 1 to restore default settings. All customised  
Heat pump/air conditioner  
Function 1: Ot  
Function 2: Cr  
Function 8: HC  
Set to 4 minutes  
Set to 3 CPH  
Set to 1  
settings will be lost.  
NOTE: See descriptions of functions on page 24.  
Fan coil  
Function 8: HC  
Set to 1  
NOTE: After changing the above settings to accommodate a cooling system, you can switch the thermostat to  
control either heating or cooling (see page 9).  
2
2
23  
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Installation and Setup  
homexpert by Honeywell THR840DUK Digital Thermostat  
Description of functions  
In case of difficulty  
Ot Minimum boiler off time: Check proper setting  
LL Minimum temperature: When the q button is  
pressed, the thermostat will not allow a target  
temperature lower than the minimum you set.  
Thermostat screen  
is blank  
•
Make sure two fresh AA alkaline batteries are properly installed (see  
page 18).  
for your system (see page 23).  
Cr Cycles per hour: Check proper setting for your  
Heating or cooling  
system does not  
respond  
•
•
Check thermostat batteries (see above).  
system (see page 23).  
ES ECO default temperature: This is the default  
target temperature when the thermostat is in ECO  
mode (see page 11).  
Make sure heating or cooling system has power. Check fuses and  
circuit breakers and replace or reset as needed.  
Ot Proportional band width: If your heating system  
is oversized for your home, you can compensate  
by increasing the width of the control proportional  
band up to 3°C.  
HCHeating/cooling options: When set to 1, the  
thermostat can control both heating and cooling  
systems (see page 9).  
•
•
Check wiring (pages 14-17) and system configuration (pages 20-24).  
Desired temperature  
cannot be maintained  
If above remedies cannot resolve the problem, the thermostat may  
have to be moved. Make sure it is not installed near sources of hot or  
cold air (radiators, windows, heating or cooling ducts).  
tO Temperature offset: In some cases, the  
thermostat must be installed in a location that  
does not accurately control temperature for  
optimum comfort in other rooms. You can set the  
thermostat to compensate for this by adjusting  
the offset.  
OSFrost protection temperature: Minimum  
temperature allowed when the thermostat is off  
(see page 8).  
•
If this symbol flashes on the screen during normal operation, a fault has  
occurred. Contact Honeywell Customer Care for assistance (see back  
cover for contact information).  
EH Electric heat: Check proper setting for your  
system (see page 23).  
uL Maximum temperature: When the p button  
is pressed, the thermostat will not allow a target  
temperature above the maximum you set.  
2
4
25  
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Appendix  
homexpert by Honeywell THR840DUK Digital Thermostat  
Limited Warranty  
Disposal and recycling  
Honeywell warrants this product for 1 year from date of purchase. We undertake to replace or  
Disposal and recycling  
repair at our discretion, products should they become defective within 1 year solely as a result  
of faulty materials and or workmanship.  
Batteries and waste electrical products should not be disposed of with household waste.  
Please recycle where these facilities exist. Check with your local authority or retailer for  
recycling advice.  
Understandably if the product has not been installed or maintained in accordance with  
Honeywell’s instructions, has not been used appropriately or if any attempt has been made to  
rectify, dismantle or alter the product in any way the warranty will be invalidated.  
Please retain these instructions for future reference.  
This product warranty states Honeywell’s entire liability. It does not extend to cover  
consequential loss or damage or installation costs arising from a defective product.  
If the product is defective, please return it together with a proof of purchase or receipt to the  
place of purchase.  
This does not affect your statutory rights.  
tm  
If you require further information about this product, call the homexpert by Honeywell  
technical helpline on 0845 604 2893.  
For a full list of terms and conditions please visit www.homexpertbyhonyewell.com.  
©
2010 Honeywell International Inc.  
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27  
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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  
www.homexpertbyhoneywell.com  
50051982-001 Rev. A  
© 2010 Honeywell International Inc  

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