Technical data

15.0 Fault Finding
55
NO
Replace PCB.
YES
NO
YES
Set to
summer mode
(display shows Of).
With water flowing out of a fully
open DHW tap does
display show
Of ?
Is there 240V
from B to D ?
Diverter Valve faulty.
NO
YES
DHW Fault
Mains Input
Transformer
Burner On
&
Fault Neons
Pump
Diverter Valve
Gas Valve
Modem PCB
Room Thermostat
Flow &
Return
Thermistors
Overheat
Thermostats
&
Flow Switches
&
Condensate Trap
Room Control
Display PCB
Fan
E
D
Diverter Valve Plug
(when unplugged)
YES
Unplug
9-way connector
from PCB. With water flowing
out of a fully open DHW tap is
there continuity
across A ?
Unplug
DHW F/S inline
connector. With water flowing
out of a fully open tap is there
continuity across
A ?
Is DHW Flow Switch
blocked ?
Replace DHW Flow
Switch.
Wiring from PCB to
Flow Switch faulty.
Unblock DHW Flow
Switch.
Unplug
Diverter Valve.
With water flowing
out of a fully open DHW tap is
there 240V from
B to C ?
Unplug
4-way PCB
connector. With water flowing
out of a fully open DHW tap is
there 240V from
E to F ?
Replace PCB.
Wiring from PCB to
Diverter Valve faulty.
Unplug
4-way PCB
connector. With water flowing
out of a fully open DHW tap is
there 240V from
F to G ?
Wiring from PCB to
Diverter Valve faulty.
PCB faulty.
NO
YES
NO
NO
NO
YES
YES
NO
YES
F
G
B
C
A