Fault Finding Solutions - Baxi 105 HE Installation And Servicing Instructions

Fault Finding Solutions Sections A to E
A
Is there 230V at:
1.
Main terminals L and N
2. Main terminal fuse
3.
Selector terminals a & b and a
& 3. PCB - A4 connector
terminals 4 & 5
B
Is there 230V at:
NO
1.
Pump
2. PCB - A4 connector terminals 3 & 6
YES
Change pump supply cable
C
1. CH system pressure 0.5 to 1.5 bar
2.
Check the tap of the automatic air
vent is opened
3.
Primary flow valve diaphragm damaged
D
1.
Continuity across flow
microswitch and PCB - A5
connector terminals 7 & 8
2.
Primary temperature sensor faulty.
Cold resistance approx. 11K ohms
(resistance reduces with increase in temp.)
3.
Fan connections correct at fan.
PCB - A2 connector, is 230V
across terminals 5 & 7
50
© Baxi Heating UK Ltd 2011
NO
YES
NO
If pump jammed, release
NO
NO
NO
YES
NO
NO
YES
NO
Check electrical supply
Replace fuse
Check wiring
Replace selector
Replace pump
Replace PCB
Re-pressurise system
Open the automatic air vent
Replace diaphragm
Flow valve rod obstructed
Replace microswitch
YES
Replace sensor
Fan jammed or faulty winding
Replace PCB
16.0 Fault Finding
NO
neon
illuminated
YES
Replace fan
Replace PCB