Worcester 28i rsf has hot water but no heating

[rapid]

Hello people

went to a boiler break down today, it was a worcester 28i rsf combi boiler. Boiler hot water output was fine. But no central heating.
turn heating demand on fan runs, pumps runs, but no ignition. No lock out light flash. Checked overheat stat on top of the boiler has continuity. Checked central heating stat (same as the hot one)-so i took it off the central heating flow pipe and put it next to hot water stat. Both have same resisitance. Check spark electrodes both fine. I am thinking is the pcb. But not really sure. Any ideas guys

 

[SimonG]

No gas advice given on open forum, if gsr then send photo of card to gasman to gain access to the inner gsr only sanctum.

 

[Dotty]

As above. Thread closed.