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8
There must be a link between
High Voltage terminals 1 &
6 and high voltage terminals
3 & 6. Make sure both links
are present
MAF STAT CONNECTED NOT CALLING FOR HEAT (BOILER NOT FIRING) WHEN MAF STAT ON MAXIMUM
NO
YES
YES
NO
NO
YES
YES
YES
NO
YES
NO
NO
NO
NO
YES
YES
NO
Is there 230 ~ 250VAC across High Voltage terminals 2 & 4?
Is there 230 ~ 250VAC across High Voltage terminals 1 & 2?
Measure DC voltage (5.1V DC Max.) across
Low Voltage
terminals 3 & 4
Is measured voltage greater
than 4.7V
Is measured resistance
greater than 11K?
Is measured voltage greater
than 4.7V
Check pipe sensor and
connections. If sound, isolate
from mains & measure resistance
across plug J2 pins 5 & 6
Is measured voltage greater than 4.19V?
Is there an external clock fitted?
Measure DC voltage (5.1V DC
Max.) across
Low Voltage
terminals 5 & 6
Check black wire of MAF stat
goes to
Low Voltage
terminal 3
and red wire of MAF stat goes to
low voltage terminal 4. Ensure all
connections are sound
Check clock is on & measure
output
Check for live supply into clock.
Replace clock if live is present
Is 230 ~ 250VAC present?
Check harness connections
to PCB. If all OK Replace
PCB
Remove MAF stat connections
and link
Low Voltage
terminals
TPV & 3. Is there 230 ~ 250VAC
across High Voltage terminals
2 & 4?
Open circuit between clock
out & High Voltage terminal
block 1
Unit mains
supply is
missing.
Check spur
e.g. fuse is
intact
Check
connections
to high voltage
terminals
2 & 3
Problem with switched live output going from High Voltage terminal 3 to
switch live of boiler
Is there 230 ~ 250VAC across High Voltage terminals 2 & 3?
15.
FAULT FINDING
14.3
PCB REMOVAL
14.3.1 Disconnect the wiring at the PCB terminal block.
14.3.2 Release the 4 clips securing the PCB and withdraw the panel, disconnecting the fan supply lead at the
fan tray terminal block.
14.3.3 Reassembly or replacement is in reverse order.
14.4
FAN REMOVAL
14.4.1 Ensure that the electrical supply is switched off and isolated.
14.4.2 Disconnect the 2 inline connectors on the fan assembly.
14.4.3 Release the screws securing the fan and withdraw if from the location runners.
14.4.4 Refitment or replacement is in reverse order.
14.5
HEAT EXCHANGER REMOVAL
14.5.1 Ensure that the electrical supply is switched off and isolated.
14.5.2 Close the isolating valves and drain down the unit.
14.5.3 Release the clip and remove the heat exchanger and its associated pipework from the unit.
14.5.4 Refitment or replacement is in reverse order. Ensure that all air locks are expelled, and check for water
soundness.
14.6
AIR FILTER REMOVAL
14.6.1 Remove the filter cover.
14.6.2 Remove the two air filters out by sliding it from the front of the unit.
