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FAULT FINDING
F
AUL
T FINDING F
AUL
T FINDING F
AUL
T FINDING F
AUL
T FINDING F
AUL
T FINDING
ESPRIT 2 -
Installation and Servicing
92
H.....4.... (DRY FIRE THERMISTOR ERROR)
94
H......n..... (PHASE REVERSAL ERROR)
Check wiring to the boiler for
reversed live and neutral
93
H......F..... (FLAME DETECTION ERROR)
Replace flame detection electrode
Is there continuity between the 2 terminal pins ?
NO
YES
Remove flame detection electrode terminal from PCB
Replace PCB
Can the fault condition be reset by switching off
the mains supply to the boiler ?
Check wiring for continuity from the
PCB to the dry fire thermistor
Check resistance using a suitable multimeter
connected across the thermistor’s terminal pins
At 25
o
C
expect
9,700 - 10,300
Ohms
At 60
o
C
expect
2,400 - 2,600
Ohms
At 85
o
C
expect
1,000 - 1,100
Ohms
Are thermistor values correct ?
Replace PCB
Replace thermistor
NO
YES
NO
YES
Is water system correctly filled and vented with a
system pressure of approximately 1bar
H9/L9
(HEAT EXCHANGER OVERHEAT)
Is the system filled and vented and all isolation
valves open, including TRV's & Bypass?
Check the pump is operating correctly in
Heating & DHW and check temp diffs across
Flow & Return.
YES
NO
Fill and vent the
system and open all
isolating valves
Are thermistor values correct ?
Check that a permanently open
bypass circuit is available during
the pump over-run period after
boiler shutdown. This can be
provided by either an automatic
bypass valve or a heat leak radiator
(no TRV) of at least 10% of the
minimum boiler output.
Replace
thermistor
YES
NO
Check resistance, using a suitable multimeter
connected across the dry fire thermistor
terminal pins.
At 25
o
C expect
9,700 - 10,300
Ohms
At 60
o
C expect
2,400 -
2,600
Ohms
At 85
o
C expect
1,000 -
1,100
Ohms
Note.
With V9 Primary Control PCB, overheat LA/HA or H9/L9 when
reset will display 3 horizontal lines and will not attempt to refire
until the temperature in the heat exchanger drops below 50
o
C.
Check Flow stat is
fitted - making contact
with pipe
YES
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