Fault Finding & Diagnosis; No Hot Water On Opening A Tap (New Installation); Fault Finding - Worcester 29CDi Classic Installation, Commissioning And Servicing Instructions

FAULT FINDING & DIAGNOSIS
7 FAULT FINDING & DIAGNOSIS
7.1 NO HOT WATER ON OPENING A TAP (NEW
INSTALLATION)
When a hot tap is turned on and only cold water is delivered, and the
boiler does not fire up, the first thing to check would be to see if the hot
and cold domestic water pipes are installed the correct way round.
To display the value of the service function:
▶ Press the button for more than 10 seconds (the display shows
). When the button lights up orange, release it. In the display
appears Digit.Letter e. g. 1.A.
▶ Press the eco button for going up (service next) or
going down (service previous) to select service function 6.d.
▶ Press the button and release it. After releasing the button will light
up orange. The display shows the current flow rate.
▶ With the hot tap turned on, the current flow rate is displayed in the
digital display. If the hot and cold DHW pipes are reversed then the
display will indicate no flow, and the display will show 0.0.
You can also use this menu item to check the hot water
flow rate, and complete the Benchmark Logbook during
installation. Carry out the sequence described, and
when the pipes are correctly fitted the boiler will display
the actual hot water flow rate in litres per minute.
Display code Description
A1 Pump has run dry or pump has stalled/seized.
A7 Hot water NTC sensor defective.
A8 Break in communication to FX/Sense controls.
b1 Code plug not detected.
C6 Fan speed too low.
E2 CH flow NTC sensor defective.
E9 Safety temp. limiter in CH flow has tripped.
EA Flame not detected.
F0 Internal error.
F7 Flame detected even though appliance switched off.
FA Flame detected after gas shut off.
Fd Reset button pressed by mistake.
Table 15
54
7.2

FAULT FINDING

This fault finding information is for guidance only.
Worcester, Bosch Group 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 during a fault. The seven segment display on the boiler fascia
give an alpha numeric fault code. Use the table below to identify the fault
button for
code and cause.
A more detailed fault finding procedure is described in the Service
Engineer's booklet.
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
(d) RESISTANCE TO EARTH
Remedy
Check for water leaks.
Free the pump or replace.
Check:
- hot water NTC sensor
- connecting lead for circuit breaks/short circuits.
Check electrical connections.
Insert code plug correctly, test and replace if necessary.
Check:
fan lead and connector, and fan; replace as necessary.
Check CH flow NTC sensor and connecting lead.
Check:
- system pressure,
- safety temp. limiters,
- pump operation,
- fuse on pcb, bleed appliance.
Is gas cock turned on?
Check:
- gas supply pressure,
- power supply,
- igniter electrode and lead,
- ionisation sensing electrode and lead,
- flue duct and CO2 level.
Check electrical connector contacts, programmer interface module
ignition leads are not loose; replace pcb if necessary.
Check:
- electrode assembly,
- dry pcb.
- Flue clear?
Check:
- gas valve; resistance, coil 1 = 190, coil 2 = 390
- wiring to gas valve.
Clean condensation trap and check electrode assembly.
Flue clear?
Press reset button again.
6 720 815 725 (2015/05)