User Manual

About your new thermostat

homexperttm by Honeywell THR840DUK Digital 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).

QUICK START GUIDE

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

2

Select heating (default) or cooling mode

See page 9

3

Set desired indoor temperature

See page 10

Cooling system is

ECO mode countdown

Heating system is

running (see page 9)

(see page 11)

running (see page 9)

ECO mode is on

 

 

(see page 11)

 

 

 

ECO

 

is showing

25.0

° C

Appears when

 

target temperature

 

 

Current temperature

 

 

(or target temperature

 

 

when flashing)

 

 

System fault

Low battery warning

Standby symbol

(see page 25)

(see page 18 to replace

appears when

 

batteries)

thermostat is off (see

 

 

page 8)

Press to change temperature (see page 10)

Press to turn ECO mode on or off (see page 11)

Press to turn thermostat on or off (see page 8)

6

7

Page 4
Image 4
Honeywell THR840DUK user manual About your new thermostat, Quick reference, Install and set up thermostat