Honeywell DT90E - Room Thermostat Manual

Introduction

The purpose of this device is to control the temperature of the HEATING when the timer allows it to be switched on.
The hot water will not be affected in any way.

Normal operation of the thermostat

Normal Display
The display will normally show the room temperature measured by the thermostat. If the flame symbol is visible*, this means that the boiler should be on.

To enquire about the set temperature
Simply press one of the arrow buttons and the display will show the set temperature. After a few seconds it will go back to showing the room temperature.

To change the set temperature
Keep pressing the arrow buttons and the display will change to show the new set temperature. Press the button to increase the temperature, and the button to decrease the temperature.

To switch on or off
Press and hold the button marked for 2 seconds to switch off. In the bottom right corner display will show this symbol.

To switch the thermostat back on, press and hold the same button again for 2 seconds. The symbol in the bottom right hand corner will disappear.

The thermostat has an energy saving ECO button

This allows the temperature to be set to a lower value for several hours, to save energy. The energy saving temperature has normally been pre-set to 18°C.

How to operate the ECO energy saving

To start the energy saving
Press the green ECO button. Set the number of hours at this energy saving temperature.

To set the number of hours
Simply press the or buttons to increase or decrease the number of hours (from 1 to 24 hours).

Display during the ECO time period
The display shows the word 'ECO'.
It also alternates between showing the time remaining in ECO mode, with an egg timer, and the measured room temperature.

To switch off the ECO energy saving mode
Press the green ECO button again. 'ECO' will disappear from the display and the thermostat will now control at the normal temperature.