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F2 fault

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robh
robh Member Posts: 6
Hello, I have an f2 fault on my Ideal logic + system 30. My gas safe engineer has serviced it with new spark electrodes, spark generator and detection electrode. The heat exchanger has be flushed with water until it runs clean.
All wires have been checked for continuity, a new PCB has been fitted and finally a new gas valve fitted. Still the F2 fault!!!
Strangely if he blocks off half the Venturi with his finger it’ll light but then extinguish when he removes it. He is now stumped so I thought I’d turn to you for help, surely someone’s seen this before and I can pass it on to my engineer.

thanks in advance.

ps condense is running freely too.

Comments

  • HVACNUT
    HVACNUT Member Posts: 5,864
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    According to the manual, F2 is flame loss, not failure to ignite. 
    Does it go to L2 (ignition lockout) if the venturi is not covered?
    I'm not familiar with that brand but it does state that that air/fuel ratio is set at the factory and there are no field adjustments to the gas valve.
    Natural or LP gas?
    What's the incoming gas pressure?
    If it's ignition lockout, one of the steps is to check the drain.
    The tech might need to call Ideal tech support. 
  • robh
    robh Member Posts: 6
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    Thanks for the very quick reply.

    Yes it does go to L2 without the Venturi covered, it try’s 5 times the  goes to, as you say, ignition lockout. It is an LPG boiler, apparently it has good incoming gas pressure and I also forgot to mention he checked the flue and all that was good too.

    The condenser trap runs freely if water is poured down it.

  • pecmsg
    pecmsg Member Posts: 4,888
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    robh said:

    Thanks for the very quick reply.

    Yes it does go to L2 without the Venturi covered, it try’s 5 times the  goes to, as you say, ignition lockout. It is an LPG boiler, apparently it has good incoming gas pressure and I also forgot to mention he checked the flue and all that was good too.

    The condenser trap runs freely if water is poured down it.

    What is the standing pressure?
    What is the pressure when trying to light, after it lights, just before is goes into alarm?
  • robh
    robh Member Posts: 6
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    Hi, if you mean gas pressure then I’ve no idea, my tech has gone now, I think he’s given up!!!

    if you mean water pressure then it is on about 1.5bar and doesn’t move during the whole process.
  • HVACNUT
    HVACNUT Member Posts: 5,864
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    robh said:
    Hi, if you mean gas pressure then I’ve no idea, my tech has gone now, I think he’s given up!!!

    if you mean water pressure then it is on about 1.5bar and doesn’t move during the whole process.
    Since the manual states the air/fuel ratio is set and tested at the factory, a call to tech support is in order by a tech with an electric meter, a manometer, and combustion analyzer. Even though I didn't see anything in the manual pertaining to a combustion test.


  • GGross
    GGross Member Posts: 1,070
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    On Ideal's website it says "LPG conversion available" how long has this boiler been installed? has it run well for prior heating seasons?
  • robh
    robh Member Posts: 6
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    Thank you all for your help on this. It turned out to be the fan even though Ideal don’t list it as a potential fault for the L2 code. On these boilers there is no separate air pressure switch, I assume the fan senses back pressure if there is a blockage. My fan must of sensed too much back pressure but if you covered half the venturi you reduce air flow and therefore back pressure. I hope this fault finding helps one of you out someday.
  • robh
    robh Member Posts: 6
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    After stripping down the old fan I now see that the fan rpm is measured. I now believe that the bearings got stiff and the rpm didn’t match the input voltage tolerance and that’s why it thought there was a blockage in the condense or flue.

    GGross