51
17.0 Fault Finding
© Baxi Heating UK Ltd 2007
Fault Finding Solutions Sections A to E
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 - A4 connector
terminals 4 & 5
Check wiring
Replace selector
3.
NO
NO
A
Pump Replace pump
1.
YES
PCB - A4 connector terminals 3 & 6
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 - A5
connector terminals 7 & 8
Replace microswitch
1.
NO
NO
Flow or Return temperature sensor faulty.
Cold resistance approx. 11K ohms
(resistance reduces with increase in temp.)
Replace sensor
2.
YES
Fan connections correct at fan.
PCB - A2 connector, is 230V
across terminals 5 & 7
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 flashing
PCB - A1 connector has 230V AC
across terminals 2 & 4
YES
Turn selector switch
to Reset position
YES
NO
NO
NO
F
NO
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