Honeywell thermostat ST9400A 1 Day 2 Channel Programmer User Manual

11

OPERATING YOUR ST900A
Overriding the Operation Without Changing the Programmes
In AUTO and ONCE operating modes, the OVERRIDE buttons switch the heating or hot water ON or OFF without altering the programme. 
When the indicator lamp is ON, pressing the OVERRIDE button switches the heating or hot water OFF until the next programmed ON time.
When  the  indicator  lamp  is OFF,  pressing  the OVERRIDE  button  switches  the heating or hot water ON until the next programmed OFF time.
The LoT™...

12

FINE TUNING YOUR ST900A
Changing from AM/PM Time Display to the 2 Hour Clock
Your  ST9400A  can  operate  on  the  12  hour  AM/PM  or  24  hour  clock  formats.  To change the format, ensure the slider is in the RUN position then press and hold the   and  buttons together for about 2 seconds. Ignore the ‘NOT VALID’ message that will appear briefly. All the displayed times will be automatically changed to the new format.
Repeating this procedure will change the clock display back to the...

1

FINE TUNING YOUR ST900A
To Enter Installer Mode:
a. Ensure the slider is in the RUN position, then press and hold  and  buttons together for 8 seconds. Ignore the ‘NOT VALID’ message that is displayed for a few  seconds.  The  message  ‘SET  UP  MENU’  will  show  briefly,  followed  by  ‘SET INSTALLER OK ?’
b. Press the  button to take you into the Installer Mode Parameter Menu.
c.  Parameter  1  is  now  available  to  change.  This  is  to  allow  you  to  change  the clock  format  from...

1

FAQ AND TROUBLESHOOTING
How  do  I  set  the  time  only,  if  the  ST900A  clock  is  not correct?
Your ST9400A contains a very accurate digital clock that is factory pre-set. Should you ever need to change the time, just follow this procedure:
a. Move the slider to the DAY/TIME position.
b. Keep  pressing  the  green   button  until  the  message  ‘SET  THE  TIME’  is displayed.  To  change  the  time,  press  the    or   buttons  until  the  correct time is shown. The message ‘IS TIME...

1

SymptomPossible CauseRemedy
ST9400A has a blank LCD displayNo power to the heating systemCheck that there is power to the heating system
Fault in ST9400ACall Installer
ST9400A indicates that Heating and/or Hot Water are ON, but radiators are cold and/or taps are running with cold water.
Temperature controls are switched off or set too low
Check that the temperature controls in the system are set to appropriate levels
Boiler or other system controls have malfunctioned
Call Installer
ST9400A shows...

1

MINI-PROGRAMMER OPERATING INSTRUCTIONS
You need only refer to this section if:
• The Mini-Programmer box is ticked on the Contents page of this booklet, or
• The  ST9400A  Configuration  Data  (page  18)  indicates  it  is  set  as  a  Mini-Programmer.
What is a Mini-Programmer?
In  a  poorly  controlled  gravity  circulation  hot  water  system,  whenever  the  boiler comes on to service the heating, there will inevitably be some circulation though the hot water storage tank, which will then...

1

Disabling / Enabling Time Periods
To disable any of the time periods ON 1 to OFF 1 or ON 2 to OFF 2, simply set the ON  time  and  its  paired OFF  time  to  the  same  time,  and  the  programme  will  just ignore them.
To re-enable the time period, simply set the two ON and OFF times to be different.
Choosing the Operating Mode 
In  a  Mini-Programmer,  some  Operating  Modes  are  not  possible.  For  example, HEATING  in AUTO  mode  and HOT  WATER  in OFF  mode  is  not  allowed.  When...

150022737-004 A
CONFIGURATION & SERVICE DATA
Configurable FeaturesOptionsInstaller Configured (tick appropriate box)
24hr or am/pm clock displayam/pm display
24hr display
Display backlight operationOff
On if button pressed
On continuously
Automatic time changeEnabled
Disabled
Number of ON/OFFs per day2 on/offs per day
3 on/offs per day
Default programmeA = standard
b = at home
C = economy
Set as Mini-Programmer *No
Yes
Configuration Data (to be completed by Installer)
The  table  below  is  for...