Combi Boiler Won't Fire Up

[Lecky133]

I have a Ferroli Optima 701 boiler that won't fire up. Also, the pilot light won't light without me lighting it manually. Could this be an electrical problem, or just the thermocouple?

[gasman]

Does the pilot light stay in once lit ???

[Lecky133]

Yes, the pilot light remains lit

[gasman]

Well the thermo-couple is OK then. So the peizo has probably failed or just a loose connection in regards to not been able to light the pilot. So your problem could be a number of things can you desribe the symptoms in more detail ? Does the pump run ? Is the thermostat calling for heat ? is the programmer ( timer ) set correctly ?

[Lecky133]

When I switch the boiler on to 'constant c/h and hot water' or if I turn the hot tap on, the boiler sounds as though it is going to fire up, but fails to do so. Sorry, I don't know much about the workings of the boiler so I can't really give a lot of detail other than this. The programmer is set as normal, so I doubt there is a problem there.

[gasman]

could be a faulty air pressure switch does the fan run as normal ?

what does the LED display ?

[Lecky133]

Yes, the fan runs ok. The LED displays the current time ??? Is this the LED you are talking about? It's the only one I can see.

[gasman]

then it may be the air pressure switch then. Pull off the silicone tubes that go from the APS to the venturi at the flue and inspect them for damge or holes and that they are not clogged up including the venturi aswell and also blow into the tubes to see if you can hear the APS operate. It will click as it opens and closes if it does'nt then replace it.

[Lecky133]

Many thanks for your help Gasman.
Much appreciated

[Lecky133]

It's a relay on the PCB that has blown.
Not as bad as I thought.
Thanks Gasman.