91
12.7 Servo Motor Blocked
Ensure ‘TIME CLEAN BRAZIER’ is
then reset to its original setting or
the brazier cleaning operation will
be repeated every time the burner
shuts down.
Note 5 - Is the servo motor correctly
set?
The stroke of the servo motor is factory
set and should not be adjusted. Check
with Grant UK for correct setting.
Note 6 - Is the boiler cleaning
interval correct?
Go to the ‘CLEAN’ sub menu of the
burner control settings and check that
‘TIME CLEAN BRAZIER’ and ‘TIME
CLEAN BOILER’ are correctly set.
Refer to 9.7.1.3
Primary fault
Secondary follow on checks
SERVO MOTOR BLOCKED
Open the
combustion
chamber door.
Is the brazier
blocked up?
No
No No No No No
Can the brazier
be opened
manually?
Is the brazier
clearance correctly
set?
Is the servo
motor operating
correctly?
Is the boiler
cleaning interval
correctly set?
Is the duration
of the brazier
cleaning period
correct (4 to 5
minutes in total)?
Is the brazier
distorted or
damaged?
Reset brazier
clearance using
Grant UK brazier
clearance gauge
Is the servo
motor correctly
set?
Replace damaged
parts and reset
brazier clearance
Reset servo
motor controls
In burner menu
reset ‘TIME
CLEAN BRAZIER’
and ‘TIME CLEAN
BOILER’ settings
Adjust servo
motor setting or
replace servo
motor if
necessary
Yes Yes
Yes
Note 1 Note 2 Note 3 Note 4 Note 5 Note 6
Yes Yes
Remove the
blockage and close
the combustion
chamber door
Yes No
H2o 60˚C
SET 75˚C
SERVO MO
Note 1 - Opening the combustion
chamber door.
Before attempting to open the
combustion chamber door, set the ON/
STANDBY switch to STANDBY.
Note 2 - Can the brazier be opened
manually?
First clear any blockage (clinker/ash)
from the brazier. To open the brazier
manually, operate the release switch
on the servo motor. Refer to Section
11.7.2.
DO NOT FORCE THE BRAZIER
OPEN WITHOUT OPERATING THE
SERVO MOTOR RELEASE SWITCH
OR THE SERVO MOTOR GEARS
WILL BE DAMAGED AS A RESULT!
Note 3 - Is the brazier clearance
correctly set?
To check the gap between the fixed
and moving part of the brazier, use the
brazier clearance gauge (supplied with
the boiler). Refer to Section 11.7.2. If it
is necessary to dismantle the brazier,
the burner must be removed from the
combustion chamber door. Refer to
Section 11.7.
Note 4 - Is the servo motor
operating correctly?
Set the ON/STANDBY switch to
STANDBY. Go to the ‘CLEAN’ sub
menu of the burner control settings and
set ‘TIME CLEAN BRAZIER’ to 0.
Set the ON/STANDBY switch to ON
and start the boiler. When the burner
display shows ’100% POWER’ set
the ON/STANDBY switch back to
STANDBY. When the burner has
completed the shut down process the
brazier cleaning operation will start
automatically. The burner control screen
will first show ‘BRAZIER CLEANING
FORWARD’ for between 2 to 2½
minutes. Then the burner fan will start
and the screen will show ‘BRAZIER
CLEANING BACK’ for between a
further 2 to 2½ minutes. Thus the total
time for the brazier cleaning operation is
between 4 to 5 minutes.
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