Combi Boiler fault, would appreciate some advice please.

I have a Fagor Combi Boiler model FE24E. Fault is that it will not ignite. It makes all the usual noises, clicks etc, but no flame. You can hear the ignition spark, click away during fire up, and there is a spark, but no flame.
There are two sealed chambers inside the boiler.
The larger outer one, contains the combustion chamber, heat exchanger, air fan pump at the top of the heat exchanger, electric safety thermostat and one of the water pipes. There is also a round plastic assembly which has two smallish rubber pipes coming out of it and going into the inlet and outlet flue, it also has two wires connected to it, going back to the control box, I am not sure of the function of this unit.
The smaller inner chamber is where the combustion takes place, it has two parallel probes going into it, which are the spark gap for igniting the gas. It also has another single probe positioned over the flame, with a single wire going back to the control box. The technical manual I have for the boiler is in Spanish, and they identify this single probe as a "Electrovalvula modulante" which googles out as a "Modulating Solenoid"
When I first starting working on the boiler, I thought it was an ignition spark problem, so I changed the Spark Transformer and the Spark Gap probe inside the combustion chamber, after changing these parts I thought I would fire up the boiler with the cover off the inner combsution chamber, and bingo, spark igniter sparked and the flame lit, great I thought. So I put the cover back on the inner chamber, and I thought I would give it another test, but this time it would not fire up. I could hear the spark clicking away inside the chamber, but no flame, so I took the cover off again, and it started working again? Now if I put the cover partially back on, it will fire up, but not when the cover is fully tightened up.
I would very much appreciate your help with this please, TIA
Regards Mark in Spain.
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"Anti-Spam" wrote in message

Mark, I am no expert on boilers, and have never seen or heard of a Fagor Combi Boiler model FE24E, so I can only generalize.
I do not know if it is a hot water or steam boiler.
A few things in general I would check if it were my boiler.
Is the solenoid opening?
Is the fuel jet blocked?
Is there a Gas supply right up to the boiler?
Does the burner have a manual safety switch, if so has it tripped?
Care should be taken while working on these things as if a gas leak occurs it could cause fire or an explosion, also I suppose the electrical system is 220 volts so it could be lethal if you touch the wrong thing so getting in someone who knows about these boilers sounds like the best shot.
Sorry that is about as far as I can go.
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On Sat, 19 Nov 2011 00:48:24 +1000, < snipped-for-privacy@truthonly.com.Sword of Baal> wrote:

Thanks for your help
Its a Hot Water Domestic Combi Boiler
I do get flame if I leave the Combustion chamber cover off, which I think answers the last questions?.
I think the gas supply to the burners can be varied, by the control board, via some sort of special gas valve, ie more heat needed then more gas supplied (would love to know how this works).
I am aware of the safety issue, but thanks for the advice anyway.
Regards Mark in Spain
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"Anti-Spam" wrote in message

-----------
Just another thought if you have a water gauge and your boiler has a connection for it you might check the gas pressure, especially if it has a gas governor (Pressure reduction valve)
I was wondering if that gas governor is closing down when you attempt to start it, or is closed and there has been a little leakage letting you start it but once it has started there is insufficient gas to run it as the valve is not opening.?
I do not know about Spain but in Sydney Australia they bring in fairly high pressure gas that requires reduction valve before the meter and in most cases another one to operate the appliance. In the older times mains gas pressure was only 5-7 inches water gauge in the gas mains in UK, NZ and Australia.
Not sure what it is now in Sydney but for some reason 11 PSI comes to mind. The old gas tanks (Gasometers) are a thing of the past there, as they now rely on both supply and that extra pressure in the mains as backup.
27 inches water gauge = one PSI from memory.
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Correct, roughly .44 PSI per foot of depth of water.
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On Sat, 19 Nov 2011 00:48:24 +1000, < snipped-for-privacy@truthonly.com.Sword of Baal> wrote:

    And you chose to open your mouth and bless us with proof of your ignorance .... why ?
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P.JM wrote in message

Well you open your mouth and prove your stupidity regularly................
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Appology, I made a mistake on namimg the single probe. that is in the Combustion chamber, its not "Electrovalvula modulanteit" should have read, "Bujias De Ionizacion" which googles out as "Spark Plug Ionization"
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