Honeywell ST9420C User Manual

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Contents
CONTROL OF YOUR SYSTEM
General Description of Controls in Your System ...................................................4
The way to use a Programmer ..............................................................................4
The way to use a Room Thermostat / Control of Your Boiler / Optimisation .........5
GETTING STARTED WITH YOUR ST9420C
Step 1: Setting the Date & Time............................................................................6
Step 2: Running a Built-in Programme .................................................................7
PROGRAMMING YOUR ST9420C
The Built-in Programmes / Your Personal Programme ..........................................8
Reviewing the Programme Times / Modifying the Hot Water Programme ............9
Modifying the Heating Programme / Disabling or Enabling Time Periods .........11
OPERATING YOUR ST9420C
Choosing the Operating Mode ...........................................................................12
Overriding the Operation Without Changing the Programmes ...........................12
The Extra Hour Function / The Holiday Function ................................................13
Enquiry Mode .....................................................................................................14
FINE TUNING YOUR ST9420C
Changing from AM/PM Time Display to the 24 Hour Clock ................................15
Changing the Installer Parameters .....................................................................15
Optimisation ........................................................................................................17
How to set your Hot Water Set Temperature .......................................................18
BOILER SERVICE REMINDER
Countdown to Service / When Service is Due ....................................................18
Shut-down ...........................................................................................................19
OPERATING YOUR DT92E
Inquiring about the Set Temperature / Adjusting the Set Temperature ...............19
Switching Off / Display Updates / Heating Indicator / Frost Protection ..............20
DT92E OPERATING INDICATORS
Low Battery Indicator / Battery Replacement / RF Communications Indicator / Lockout ...21
DT92E ENERGY SAVING ECO FEATURE
Entering ECO Mode and Setting the Energy Saving Time Period ......................22
What Happens in ECO Mode? ............................................................................22
How to Exit ECO Mode .......................................................................................23
FINE TUNING YOUR DT92E
Changing the DT92E Installer Parameters .........................................................23
OPERATING YOUR CS92A HOT WATER THERMOSTAT
Basic Operation / Battery Replacement / Error Indications ................................ 25
OPERATING YOUR BDR91T RELAY BOX (IF INSTALLED)
BDR91T Controls Layout / Automatic Operation ................................................26
Temporary Manual Override / Loss of Wireless Communications ......................26
FAQ AND TROUBLESHOOTING
Frequently Asked Questions ...............................................................................27
Troubleshooting Guide........................................................................................29
CONFIGURATION & SERVICE DATA
Configuration Data (to be completed by Installer) .............................................34
Boiler & System Service Log ..............................................................................35

Honeywell ST9420C Specifications

General

Model	ST9420C
Category	Thermostat
Display	LCD
Channels	2
Power Supply	230V AC
Mounting	Wall-mounted
Contact Voltage	230V AC
Contact Current	3A resistive, 1A inductive
Switching Type	SPDT
Type	Programmer
Programs	7-day programming
Compatibility	Compatible with most heating systems