Fault Finding And Diagnosis; Fault Finding - Worcester GREENSTAR Ri Installation And Servicing Instructions

FAULT FINDING AND DIAGNOSIS

7 FAULT FINDING AND DIAGNOSIS
7.1

FAULT FINDING

This fault finding information is for guidance
only. Worcester cannot be held responsible
for costs incurred by persons not deemed to
be competent.
The electronic control system for this boiler
incorporates a blue central indicator. This normally
confirms the permanent mains supply but, by flashing at
different rates during a fault, provides a guide to the
cause as listed.
Blue light
indication Fault
No light No power at
control board
Light ON Boiler ON but not
operating during
demand
Ignition lockout
Slow flash
(mostly off,
flashes on)
Flue overheat
Slow flash
(mostly on,
flashes off)
Heat exchanger
overheat
Flue pressure
switch
Fast flash Volatile lockout
(sensor, fan or
code plug)
2 pulses
5 pulses
Tab. 22
60
Possible solution/check
Permanent mains supply to boiler.
Boiler mains switch ON.
Fuse F1 - 2A Slow blow.
Fuse F2 - 1.25A Anti-surge.
Transformer (both coils below 100 Ω.
Otherwise replace control board.
Live demand at ST2 terminal L
Manual bypass is open.
If CH is working check HW controls
If HW is working check CH controls (i.e. external diverter valve,
frost stat, room stat/programmer.
Otherwise replace board.
Gas present and at correct pressure?
Combustion CO level?
2
Flue condition.
Ignition electrodes/cables/connections.
Flame sense electrode/cable/connection
Gas valve (coils 140 - 190 Ω)
Otherwise control board.
Flue temperature too high.
Heat exchanger baffles have been removed and not replaced.
Water pressure/dry.
All air vented?
Pump/cables/connections.
Water leaks/blockages.
Safety thermostats/cables/connections.
Otherwise replace the control board.
Blockage in the flue system.
Temperature sensor (8 000 - 20 000 Ω)
Wiring/connections to sensor.
Fan/cable connections.
Code plug fitted?
Service mode switch in min position
Service mode switch in max position
This fault finding system assumes that the appliance has
been operating normally until the time of failure (i.e. not
a first installation error).
PRELIMINARY CHECKS : Preliminary electrical system
checks are the first electrical checks to be carried out
during a fault-finding procedure. On completion of the
Service/Fault-Finding task which has required the
breaking and remaking of electrical connections, check:
(a) EARTH CONTINUITY,
(b) SHORT CIRCUIT CHECK,
(c) POLARITY and
(d) RESISTANCE TO EARTH.
- is there a demand?
R
6 720 644 744a (2010/10)