I have had replaced so thermostats, diafram, heat exchanger also the have tested gas flow and water, ignition and burner all seem to be ok but this keeps happening:-
SATURDAY 14/02/2009

06.30……C/H ON ONLY / LOCKOUT +PUMP RUNNING / BAR PRESSURE OK
12.00…….C/H ON….TOOK SHOWER AFTER SHOWER LOCKOUT/NO PUMP RUNNING / BAR PRESSURE OK
17.00…….C/H ONLY / LOCKOUT / PUMP RUNNIG / BAR PRESSURE OK
22.15…….TURNED C/H ON …OK / BAR PRESSURE OK

SUNDAY 14/02/2009

07.10……..C/H ON …ALL OK / BAR PRESSURE OK
13.00……..C/H ONLY / LOCKOUT / PUMP RUNNING. / BAR PRESSURE OK
15 45……..C/H ONLY / LOCKOUT NO PUMP RUNNING. / BAR PRESSURE OK
17.05……...C/H ON OK / RAN BATH WATER COLD / LOCKOUT. / BAR PRESSURE OK
20.00 …….C/H ON OK / TURNED KITCHEN TAP ON COLD / LOCKOUT. / BAR PRESSURE OK

MONDAY 16/02/2009

07.00……..C/H ON OK / BAR PRESSURE OK
08.30……..C/H ONLY LOCKOUT / PUMP RUNNING / BAR PRESSURE OK
22.00…….. C/H ONLY LOCKOUT / PUMP RUNNING / BAR PRESSURE OK

TUESDAY 17/02/2009

07.00…….. C/H ONLY LOCKOUT / PUMP RUNNING / BAR PRESSURE OK
08.00……...C/H ONLY LOCKOUT / PUMP RUNNING / BAR PRESSURE OK
12.30……... C/H ONLY LOCKOUT / PUMP RUNNING / BAR PRESSURE OK
16.45……... C/H ON OK / TURNED KITCHEN TAP ON COLD / LOCKOUT. / BAR PRESSURE OK

WEDNESDAY 18.02.2009

07.00………. C/H ONLY LOCKOUT / PUMP RUNNING / BAR PRESSURE OK
16.00………. C/H ONLY LOCKOUT / PUMP RUNNING / BAR PRESSURE OK
17.00………. C/H ONLY LOCKOUT / PUMP RUNNING / BAR PRESSURE OK

LesG, February 2009

have you checked condition of both electrodes?, maybe ignition pcb or main pcb?, all boiler engineers should be able to check these! or just cut your losses and pay vokera (about £185, which inc. parts, labour & vat!) to come and fix it in one visit!

Big A, February 2009