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© Baxi Heating UK Ltd 2009
16.0 Fault Finding
Fault Finding Solutions Sections A to F
Is there 230V at:
Is there 230V at:
Main terminals L and N Check electrical supply
1.
NO
Main terminal fuse
Replace fuse
Replace PCB
neon
illuminated
2.
YES
Selector terminals a & b and a
& 3. PCB - M1 connector
terminals 9 & 10
Check wiring
Replace selector
3.
NO
NO
A
Pump Replace pump
1.
NO
PCB - M1 connector terminals 8 & 15
Replace PCB
2.
NO
Change pump supply cable
YES
B
CH system pressure 0.5 to 1.5 bar Re-pressurise system
1.
NO
Primary flow valve diaphragm damaged Replace diaphragm
Flow valve rod obstructed
3.
YES
Check the tap of the automatic air
vent is opened
Open the automatic air vent
2.
NO
NO
C
YES
Continuity across flow
microswitch and PCB M2
connector terminals 3 & 4
Replace microswitch
1.
NO
NO
Primary temperature sensor faulty.
Cold resistance approx. 11K ohms
(resistance reduces with increase in temp.)
Replace sensor
2.
YES
Fan connections correct at fan.
PCB - M5 connector, is 230V
across terminals 28 & 29
Fan jammed or faulty winding
Replace PCB
Replace fan
YES
3.
D
If pump jammed, release
Check and correct if necessary
1. Electrical and pressure tube connections
2. Blockage of pressure tubes
3. Restriction in flue
4. Venturi
NO
E
Replace air pressure
switch
Gas at burner
Ensure gas is on and purged
Replace PCB
Replace gas valve
neon illuminated
PCB - M4 connector is approx 230V AC, terminals
36 & 38
YES
Turn selector switch to
‘Reset’ position
YES
NO
NO
NO
F