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If after checking all previous points the error code is still present,
this suggests that the heat exchanger has become partially
blocked. See section 12.11 for major service of heat exchanger.
2
8
Fault Code =
and
.
The fan is stationary or there is no fan speed signal.
Check the wiring to the fan.
Check the fan and replace as necessary. See section 12.3 for
fan removal.
2
9
Fault Code =
and
.
The fan is stationary and open circuit.
Check the wiring to the fan.
1
8
Fault Code =
and
.
The heating flow thermistor is detecting a temperature in
excess of 100 C.
Check that the pump is functioning correctly.
Check that the system is not air locked.
Check that the flow rate through the installation is high enough.
Refer to section 4.3.
1
9
Fault Code =
and
.
The heating return thermistor is detecting an excessive
temperature.
Check that the pump is functioning correctly.
Check that the system is not air locked.
Check that the flow rate through the installation is high enough.
Refer to section 4.3.
2
5
Fault Code =
and
.
The rate of temperature rise measured by the heating flow
thermistor is too high.
Check that the pump is functioning correctly.
Check that the system is not air locked.
Check that the flow rate through the installation is high enough.
Refer to section 4.3.
13.2 Central Heating
If the central heating fails to operate, or the temperature
provided is poor, check the following:
Check that all external controls are calling for heat.
Check that the boiler controls are set correctly, see section 11.
Increase temperature or return to 'Normal mode'
if necessary.
If there is still a problem, check that no domestic hot water taps
are dripping.
A dripping tap can prevent the boiler from
operating in the central heating mode. Repair any leaking taps
as necessary.
13 Fault Finding
13.3 Thermistor Characteristics
All three thermistors used on the boiler can be checked for
accuracy against the chart below if their performance is suspect.
Note that there is no error message displayed for a fault
involving the Domestic Hot water thermistor.
The thermistors should be checked at both hot and cold
temperatures.
13.4 Combustion
If the combustion CO
12.6 is too high and cannot be adjusted, or the CO levels
measured at full rate are unacceptable, then the following
possibilities should be investigated and cured.
A. Check the flue system has been correctly installed and that
both air and flue ducts are unobstructed internally, see section
7.5.
B. Ensure that correct terminal clearances are observed and
that product recirculation is impossible, see section 3.3.
C. Ensure that the condensate drain is not blocked. Refer to
section 12.5 for cleaning of the condensate drain and section
14.21 for removal if faulty.
D. Check the condition of the burner and clean or replace as
,
directed in section 12.3.
E. Check and clean the air inlet to the fan and check that the
seals are in good condition as directed in section 12.3.
F. If after checking all previous points the heat exchanger may
have become partially blocked, see section 12.11 for major
servicing of the heat exchanger.
13.5 Operating Procedure
Refer to sections 11.8 to 11.12 if necessary to check for correct
operation of the central heating and domestic hot water.
31
Temperature ˚C
Resistance (Ohms)
0
35400
10
22500
20
14700
25
12000
30
9835
40
6712
50
4672
60
3311
70
2388
80
1749
90
1300
100
980
110
749
measured during servicing in section
2
221874A
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