Ideal mini c28 - Faulty temp probe?

Discussion in 'Plumbers' Talk' started by alexjb1989, Jan 17, 2023.

  1. alexjb1989

    alexjb1989 Member

    Hi all,

    Long time no speak! Since replacing my PCB ignition board, the boiler has been running like a dream!

    Recently, I have noticed that after the boiler has been running for a time, it starts cutting out...stops for a bit, fires up again then sometimes runs for a bit or for 2 seconds!

    It has been getting worse. It is much worse when the return flow is warm. If cold, it works for longer.

    So, I flicked the switch to engage the other lamps in diagnostic mode (as to why these are not permanent, I have no idea!).

    When it cuts off, the 2nd and 3rd lamp flash together. According to the fault finding manual, this is a 'Faulty CH temperature probe NTC' Now, this would make sense with having something to do with it not being happy with return flow ....?

    My question: Shall I replace the temperature probe? They are like £5 on Ebay.

    Any advice? I have 2 temperature probes. Do I need to replace them both? One is on the return manifold, and the other is one is behind the CH flow switch.

    It appears on some boilers you need to drain them down to do this, but on others, they are in a pocket - so do I not need to?

    I have a video of the fault, but it is as described above. Once it is warm and the fault starts it will only fire up for seconds....when it is cold it works OK.

    Any help is much, much appreciated.

    Many thanks,
  2. alexjb1989

    alexjb1989 Member

    Update! Just bought 2 of these just so I am ready....

    Any help on replacing them would be grand!
  3. Mike83

    Mike83 Screwfix Select

    You need to drain down.
    Be careful you don’t get water in the electrics.
  4. alexjb1989

    alexjb1989 Member

    Thank you.

    Bugger, I was hoping I wouldn't have to drain down.

    I will put a bag over the electrics just in case!

    Assuming I can just drain the boiler down as it is the highest point in the house using the drain valve?

    Cheers again.
  5. alexjb1989

    alexjb1989 Member


    All sorted! While I had it drained down I replaced the temperate probe thermistor and removed the dhw heat exchanger and cleaned it!

    Boiler working a treat!

    Now to get it serviced.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice