Troubleshooting Guide - Honeywell ST9400A User Manual

Troubleshooting Guide

This is a quick guide to help you diagnose and cope with possible problems with
ST9400A. For further assistance, please contact your Installer.
Symptom
ST9400A has a blank
LCD display
ST9400A indicates
that Heating and/or
Hot Water are ON, but
radiators are cold and/
or taps are running
with cold water.
ST9400A shows the
message 'INTERNAL
FAULT'
When the slider is
moved to the HOT
WATER position, the
display shows 'NOT
VALID'
FAQ AND TROUBLESHOOTING
Possible Cause
No power to the
heating system
Fault in ST9400A
Temperature controls
are switched off or set
too low
Boiler or other
system controls have
malfunctioned
Fault in ST9400A
ST9400A has been
configured as a
Mini-Programmer
Remedy
Check that there is power to the
heating system
Call Installer
Check that the temperature controls
in the system are set to appropriate
levels
Call Installer
Call Installer
Check the Contents page of this
booklet or the 'Configuration &
Service Data' section (page 18)
to see if your ST9400A has been
configured as a Mini-Programmer.
Call Installer to check if this is
correct for your heating system.
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