Fault Finding - Saunier Duval ISOMAX F 28 E Installation And Operating Instructions Manual

Wall mounted modulating combination boiler
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FAULT FINDING

Before trying to operate the boiler make sure that :
• All gas supply cocks are open and that the gas
supply has been purged of air.
• The heating system pressure is at least 1 bar.
• There is a permanent mains supply to the boiler.
• The fuse on the PCB is intact.
WARNING. Always isolate the boiler from the elec-
trical supply before carrying out any electrical re-
placement work.
Always check for gas soundness after any service
work.
Table 1
Voltage
230 Volt
24 Volt
15 Volt
Display
The ISOFAST has an on-board fault diagnostic system. Should a fault occur on the boiler, the warning LED at
the top of the user display
fault has occured.
A fault code is displayed on the left hand side of the LCD display, whilst at the same time, the letters FF
appear with a telephone symbol.
30
Measured value
230 V AC
maximum 33V DC
minimum 20V DC
15V + 0.5V
5V + 0.5V
will illuminate and the LCD display will indicate the precise area where the
09
Should there be any doubt about the voltage sup-
ply to any of the components, it is possible to carry
out a simple electrical test to ensure all is opera-
tional in that area.
To carry out the electrical test, gain access to the
main Printed Circuit Board (PCB), as described pre-
viously, and measure the voltages according to
table 1.
Measuring point
Between terminals H8.1 and H8.2
Between terminals B2.4 and B2.7
Between terminals B2.4 and B2.2
Between terminals B2.4 and B4.2
FF
Sec 052

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