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Biasi Riva Plus HE - Water dripping from automatic air purger valve

Discussion in 'Plumbing and Central Heating' started by Adam Stone, 15 Dec 2019.

  1. Adam Stone

    Adam Stone

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    Good Morning All,

    Im wondering if anyone may be able to help or advise please.
    I have an issue I believe is tied to a leak coming from the combi boiler (Biasi Riva Plus HE M296 28SMC, 2015 Model):

    Last night the RCD on my home electrical system consumer unit tripped, after much hunting, unplugging and isolating, we discovered that it was tripping as soon as there was a demand from the boiler (hot water and central heating demand). We tested this and can consistently induce the fault by either having the hot tap on or having the central heating make a demand.

    I removed the cover to take a look if there was anything obvious. Sure enough, on top of the pump itself, coming from Item Number 26 on the diagram, the grey capped "automatic air purger valve". There was a small but consistent weep - Id estimate one drip per 30 seconds-ish.
    Furthermore the immediate area was coated in a limescale type crud - evidence that it had been like this for a while. Is water meant to come out of this valve? I have attached an image to help illustrate. I had wiped most of the water away but if you look carefully you can see the first couple of drips below the grey cap just off to the left slightly.

    How and why this weep could cause a short and trip the RCD is the query - the most obvious possibility is that it sits on top of the pump unit itself and the water has seeped into the pump itself, onto the electrical gubbins within - this would do it I suppose? Perhaps its as a result of a demand being made , the pump energising causing the subsequent short?

    Course of action : 1.stop the leak 2.dry out the pump 3.reassemble and try again?
    Question 1: Automatic air purger valve - is it meant to remain open all the time for normal operation?
    Question 2:Automatic air purger valve - Is there meant to be water coming out of it
    Question 3:Automatic air purger valve - replace the whole assembly or change seals?
    Question 4: Pump itself - if it has seen water inside , is it salvageable/repairable?

    Any directions, tips or words of warning before I get in and about this?

    I really appreciate and welcome comments or advice - thank you very much all.
    Adam
     

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  3. terryplumb

    terryplumb

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    No ,water shouldn't come out.
    Yes ,it should release air automatically.
    You need to have it replaced.
    If water gets onto any electrics ,or electronics within the boiler ,it can cause RCD to trip.
     
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  4. Adam Stone

    Adam Stone

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    Thanks @terryplumb , presumably I just pull that metal clip to release the valve - will water shoot out or anything as that comes away? do I need to release all the pressure out of the system first or anything? And finally do you know where I can buy parts?
     
  5. ianmcd

    ianmcd

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    you need to drain the boiler to replace the Automatic air valve AAV, as a temp measure tighten the grey cap and it will stop leaking, sounds like you will need a new pump head too though
     
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  6. ianmcd

    ianmcd

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  8. CBW

    CBW

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    I’ve had it where the pump has failed and blow the 3A fuse, if this is the case you will need a new pump/head and it won’t work until it’s replaced.
     
  9. Adam Stone

    Adam Stone

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    @ianmcd and @The Novice thanks for your messages.
    So I cracked on and drained the system back and isolated the water source.
    Dismounted the AAV and saw instantly that it was clogged up with limescale and general build up of crud. Once that was off, cleaned and serviced , I took the pump head off and sure enough water had been seeping into it and pooling to the point where the coil and the contacts were sitting in water. It had been seeping in slowly through the mating face where it mounts onto the other side of the pump - it was absolutely drenched and had begun to rust etc.

    Im not even mildly surprised that it was tripping the circuit. I took the whole thing apart and cleaned it very well then got my wife's hairdryer on it. Once it was dry I used a clean cloth soaked in contact cleaner to get right into the coil contacts. I cleaned everything thoroughly, lubed up all the seals and got it completely dry inside.
    Its now reassembled and in place - the leak has stopped as the AAV is now doing its job, just fired it up and its all good! Fault cleared!
    saved myself a pretty penny and also learned something in the process !
    I appreciate the input and suggestions guys, thank you.
    Adam
     
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  10. terryplumb

    terryplumb

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    Good on ya Adam !!
    Keep checking the AAV for a week or two ,in my experience ,once failed ,its better to replace.
    The cap should not be closed ,but left slightly open in normal operation.
     
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  11. schnellyb

    schnellyb

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    Hi, I’m hoping that I can get some advice/guidance. I have a Biasi M110.32SME, which I understand are not good boilers, which has generated a very slight leak and loses pressure weekly although it still works. Having looked under the cover a valve which I think might be an auto air purger (located above the pump) looks full of ‘gunk’. Is this likely to be my problem? And if so is it an expensive fix if I get an engineer out? I’ve attached a photo to show the part. Very grateful for any guidance/clarification.
     

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  12. Madrab

    Madrab

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    @schnellyb - you really should start your own thread rather than pick up on a old thread as the information may not be the same.

    It looks like the same issue whereby the AAV is leaking but please start a new thread.
     
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