Viessmann KW10 Operating Instructions And User's Information Manual page 9

Diagnostics
Failure, Cause, Correction
Failure
Heating system does not activate
(only GREEN power LED is
illuminated)
Heating system does not activate
(GREEN power LED is not
illuminated)
Burner does not activate, or
activates intermittently
(RED fault LED flashes)
Burner does not start
*1
Red LED does not flash when Honeywell S8600 ignition control module is used with boiler.
Cause
Thermostat is not set to a
sufficiently high temperature
Power switch " " is in " "
position
Main power to boiler control and
heating system has not been
activated
Fuse on Vitotronic boiler control
has deactivated heating system
Fixed high limit (FHL) tripped
*1
No fuel
Control calls for heat but burner
*1
does not respond
Power venter (if installed) will not
activate or is defective
Correction
Adjust thermostat.
Ensure power switch " " is in " " position.
Activate main power; ensure 120 VAC is
supplied to control (receptacle).
Replace fuse with same type and rating
(F1: T 6.3 A / 250 V, slow blow).
Reset FHL by pushing in the pin, labelled with a
" " (using a ballpoint pen).
If a "click" can be heard, the limit was tripped.
If the limit requires multiple resets, please
contact your heating contractor immediately.
with oil: Ensure sufficient supply of oil
with gas: Open main gas supply valve
or
contact your local gas utility
Attempt to reset burner using reset button on
the burner (underneath burner hood).
If still unsuccessful, please contact your heating
contractor.
Contact your heating contractor.
Operation
9