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Thread: Suggestions - Hissing Noise From Machine

  1. #1
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    Suggestions - Hissing Noise From Machine

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi All,
    Over the past few weeks I have noticed a very quiet hissing noise coming from my Izzo Duetto II. Not entirely sure where it is coming from - but it does not yet appear to be impacting on the machine's ability to function (yet).

    The hissing continues after the machine has switched off, maybe for an hour or so (haven't timed).

    Machine is 7 years old. Over the past 18 months I have been getting increasingly interested and involved in servicing it myself as much as I can. Did a general service today to see if that spontaneously fixed it (but no luck).

    I would love anyones advice as to what the hissing could be - what I can check, and any suggested fixes.

    Looking forward to your suggestions.

    SD.

  2. #2
    Senior Member JMcCee's Avatar
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    I'd bet my wife's pumpkin scone recipe it's the anti-vac valve hence the tapering off over an hour as it cools down when turned off. Easy way to tell is whilst the hiss is there give the pin a twiddle or take it out and smear a little food grade grease on the 'O' ring (when its cold). Plus they're regarded as a consumable so just get another from CP.

    I hope I'm wrong cos I'd like to get rid of that recipe.
    Last edited by JMcCee; 5th August 2018 at 07:35 PM.
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  3. #3
    Senior Member topshot's Avatar
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    As MJcCee said, it will be the anti-vac valve, it's simple to get out, apart and cleaned. That is all it will need most of the time.

    They are cheap to buy though.
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    Thanks JMcCee and topshot. You're suggestions are very much appreciated.

    Wish me luck!

  5. #5
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    Think I've found the culprit.

    And @JMcCee - your wife's pumpkin scone recipe is all mine!

    https://youtu.be/_VoJ72otYqU
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  6. #6
    Super Moderator Javaphile's Avatar
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    To be clear, on most machines the anti-vac valve and the safety/over-pressure valve are two separate valves as they perform 2 very different functions. I've no experience on this machine though, have they managed to combine both functions into a single valve?


    Java "Clarity is good" phile
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  7. #7
    Senior Member topshot's Avatar
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    Quote Originally Posted by Javaphile View Post
    To be clear, on most machines the anti-vac valve and the safety/over-pressure valve are two separate valves as they perform 2 very different functions. I've no experience on this machine though, have they managed to combine both functions into a single valve?
    The Dueto II has both anti vac and safety valve.

    It's unusual for a safety valve to fail, but it can happen, like scottydogs has.

    Either it needs adjusting, or just replace it, they don't cost much.

  8. #8
    Senior Member flynnaus's Avatar
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    Quote Originally Posted by Javaphile View Post
    To be clear, on most machines the anti-vac valve and the safety/over-pressure valve are two separate valves as they perform 2 very different functions.
    You're right but it looks like the valve in scottydog's video is connected directly to the boiler


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    Quote Originally Posted by topshot View Post
    It's unusual for a safety valve to fail, but it can happen, like scottydogs has.

    Either it needs adjusting, or just replace it, they don't cost much.
    You shouldn't try to adjust a safety valve, they are pre-adjusted and usually have a seal to 'lock' the adjustment for safety reasons (so nobody is tempted to tighten them to stop a leak and prevent them from safely venting excess pressure before something ruptures catastrophically). Some of the ones we get in as spare parts even come with a calibration certificate. In the video above the seal is the little copper disc on the right hand side of the valve near the top.
    Generally if a safety valve leaks, it is either the thread leaking where it is screwed into the boiler, or the valve itself is leaking after the boiler has overpressurised due to a faulty pressurestat. Safety valves are only designed to open in case of a major fault, so are often prone to leaking after they close again when the boiler is depressurised.
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  10. #10
    Super Moderator Javaphile's Avatar
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    Quote Originally Posted by flynnaus View Post
    You're right but it looks like the valve in scottydog's video is connected directly to the boiler

    Many machines have them both mounted directly to the boiler. In my experience the safety/over-pressure valve has always been mounted directly to the boiler with the anti-vac valve being mounted directly to the boiler more commonly among the home and prosumer machines than in the commercial machines where with their additional space they frequently have them mounted off the boiler.


    Java "So many valves...need more handles!" phile
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  11. #11
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    Looks to me that your safety valve is leaking, you may need to replace this part, unfortunately the safety valve that you have cant be adjust, also is call safety valve due to if the boiler overheats realize the extra pressure. It is a SAFETY mechanism

    This can happen due:
    The safety valve is not sealing properly
    Over heat - check you pressure switch

    Regards
    Renzo
    Old due to tare and ware
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  12. #12
    Senior Member topshot's Avatar
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    If my memory serves me correctly, there was an issue with the safety valves on the Dueto II, where they were prone to leaking when they were not very old.
    There was/is an upgraded valve available for replacement.

  13. #13
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    I think Izzo use the same safety valve than La Marzocco, this means that they are great, I am using at the moment a different one, Is hard to say which one is better because should last at least 5 yeas plus depending on your water, and pressure....They are some safety valve which realize pressure when you reach 1.2 or 1.5 or 1.8 so on that's depend on the manufacture
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  14. #14
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    Safety valve replaced - and problem now solved!

    Thanks all for your help and comments!


    (Now for the second issue......which has just become more pressing!)
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