boiler shows f1 / low pressure, but pressure reads fine

Discussion in 'Plumbers' Talk' started by michael9, Nov 22, 2021.

  1. michael9

    michael9 New Member

    I've been trying to figure this one out for a bit now, but failing to come up with a reasonable answer – any thoughts or suggestions would be appreciated.

    We've got an Ideal combi 24 boiler, a bit old but not so bad (10 years). Had an F1 fault a few weeks back, but pressure was around 0.7bars. I increased it to ~1.3 and that cleared it. A few weeks went by and the F1 returned, this time the pressure stood in the normal range at (~1.3-1.5) so I decided best not to add any more water and end up over-pressurising it. Called an engineer to visit later in the week, but by the next morning it was fine, so the engineer basically shrugged and said they couldn't identify the fault. They suggested a power flush might help solve it, but they weren't sure.

    Anyway, it happened again a day after they left and once again, 24-36 hours later was fine and working again with no intervention. Now – a week later we're once again with the F1 fault and no clue when it will (hopefully) work again.

    I'm not a plumber so I don't want to be the one messing around with it, but costly engineers without any answers aren't helping and i'm not convinced we need a fully new boiler over this.

    Anyone experience this before? Any thoughts? Cheers
  2. Sean Stringfellow

    Sean Stringfellow New Member

    Have you tried resetting the boiler? Or maybe try topping it up to say 1.5 bar. I have the same boiler and get the f1 every couple of weeks... Or days if using the heating. Put a plastic jug under the condensate pipe, and a a small sandwich bag around the little copper pressure relief pipe that'll come out the wall. It could be the heat exchanger on its way out but then if the pressure is OK then maybe it's some sort of sensor. These boilers seem to pack in after 10 years anyway
  3. pppmacca43

    pppmacca43 Super Member

    I would guess if the pressure is correct and you are getting F1 fault it could be a faulty pressure transducer. Simple fix if so for a gas safe engineer
  4. Vin

    Vin Active Member

    Pressure sensors often get clogged with sludge which stops them from reading properly, this is probably why a power flush was suggested.
    Does seem an expensive fix though, I would change the pressure sensor first.
    pppmacca43 likes this.
  5. pppmacca43

    pppmacca43 Super Member

    If the system is dirty a flush will help prevent it happening again. The transducer would still need changing though. Personally I would just get it changed, they are about £20-30 and can be changed quickly. If it fails again in a short amount of time then maybe a more expensive flush could be needed but boefully that could be avoided.
    This is all assuming it is actually the pressure transducer that is faulty and it’s not something else.
    Vin likes this.

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