Fault Finding - Baxi Solo 3 Installation And Servicing Instructions

Before starting FAULT FINDING carry out preliminary
electrical system checks i.e. Earth Continuity, Polarity,
Short Circuit and Resistance to Earth. Ensure that the
system is correctly pressurised.
START
Ensure external
controls are calling
for heat
YES
Is
there mains voltage
at P/L input ?
YES
Is
there mains voltage
at Pump L output ?
NO
Check external
NO
wiring
YES
Check fuse on
circuit board
Change PCB
No continuity
across fuse,
change fuse
YES
Check pump wiring
YES
Investigate
pump
NO
Replace
thermostat
Supplied By www.heating spares.co Tel. 0161 620 6677
YES
Does pump run ?
NO
Is
"Boiler On"
light on ?
NO
YES
Is
there mains voltage
at S/L input ?
YES
Change
potentiometer
Note: This can occur if
the boiler has
overheated
Reset by turning
control knob OFF, wait
10 seconds then turn
ON
Does
lockout light
go out ?
NO
Is there
continuity across
the overheat
thermostat ?

13.0 Fault Finding

YES
Does fan run ?
NO
Is
lockout light
on ?
NO
NO
Is
"Fan On"
light on ?
NO
Check control knob
is turned on
Check that the wires
are connected to the
thermostat sensor
YES
Check that the fan &
pressure switch plug is
connected
Check continuity
across sensor
(1 M OHM at 20 o C)
No continuity - change
sensor
Check continuity
across pilot solenoid
(1.5 K OHM)
No continuity - change
pilot solenoid
Check Potentiometer
(see table)
NO
Replace harness
Is
there a clear
constant spark at
the electrode ?
NO
Is
"Pilot On"
light on ?
YES
Check & clean
electrode. Check gap &
lead
YES
Change PCB
Note: Under cold
conditions fan run up
time may exceed
1 min
Check pressure switch
pipes for leaking or
blockage
Is there
continuity between
C & NC terminals
on the pressure
switch ?
YES
NO
Replace pressure
switch
Replace fan
Is
there mains at
the fan
connection ?
YES
Replace fan
YES
45