Fault Finding And Diagnosis; Fault Finding - Worcester GREENSTAR 24i Junior Installation, Commissioning And Servicing Instructions

Expansion vessel
8 716 105 545 0
GC No. H05 206
Flue sample plug
- vertical adapter
8 710 506 199 0
Sump gasket
8 716 113 829 0
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.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.
Blue light Lockout reset
indication button
Off Off
On Off
6 720 802 047 (2013/05)
O ring - Siphon
8 716 113 851 0
Flue sample plug
- air intake
8 716 111 253 0
Fault Possible solution/check
No power at control Permanent mains supply to boiler.
board
Fuse F1 - 2.5A.
Otherwise replace control board.
Boiler not operating Live demand at ST10-L
during central heating
Fascia mounted timer (if fitted)
demand (HW ok)
CH knob in winter position
Diverter valve
Control board
Boiler operating without Some older thermostats (containing capacitors) may give a low voltage return at
live demand at ST10-L ST10-L
R
(from external room
Check that there is no permanent live at ST10-L
thermostat timer)
Boiler not operating Ensure cold inlet DHW outlet are correctly piped i.e. are not crossed piped.
during hot water demand
Flow Turbine test:
(CH ok)
▶ Check for 5 volts d.c. across red and black wires
▶ Check for 2.5 volts d.c. across the yellow and red wires with the water flowing.
Check diverter valve, motor and control board.
Boiler not operating Fan
during any demand.
Control board
(from external room thermostat/timer)
R
when the thermostat contacts are open.
R
FAULT FINDING AND DIAGNOSIS
Terminal end
8 718 681 828 0
Flue sample plug
- gas outlet
8 716 111 252 0
from another source.
R
53