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Discuss Baxi Instant 80HE not detecting water flow in the Plumbing Forum area at

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  1. Jon Weaver

    Jon Weaver New Member

    ** First of all, I am not Gas Safe approved, so I understand that there might be a limit to the help people offer **

    Have have just renovated a house for my In-Laws and the last job (why did I put this off??) is the boiler.

    I am coming here as Baxi give me snippits of help, but keep refusing to talk any more as I am not "Gas Safe", so I hope someone here might be able to help.

    It has an Baxi Instant 80HE, which only intermittently detects HW flow... It works when I turn on the bath tap (lots of water), but not the sinks (lower flow)..

    I have looked at the mechanism which detects flow, and its obvious what the issue is.. When I turn on the tap, the "pin" that presses the microswitch comes out long and hard.. But when I turn on the sink taps, it only comes out 1/2 way and I can easily push it back.

    At the weekend I had a look at the diaphragm and associated mechanism and it was sound.. I cleaned of a bit of scale and it made little difference.

    So then I moved onto the "Venturi" which was something that Baxi told me to look at. They said that sometimes the splines come off of the cage. So I removed the cartridge, and to my surprise, the Venturi was completely missing. I checked inside the opening with a mirror/torch and its not there. The Venturi is awol.

    So I would hope this could be the cause.. But a call to Baxi today resulted in them telling me that it WAS there as the boiler wouldn't work at all without it and. They refused to accept that in my case the venturi was missing and almost implied I was lying.. They said the boiler would not work AT ALL without a Venturi and simply refused to speak to me or give me any more advice.

    Does anyone with Baxi knowledge know why my venturi is missing? And why the boiler still works??.

    How confident are you that if I simply replace the venturi is will solve my problem?

    Thanks in advance for any advice.. I need to get this fixed quickly now as they have moved in and have no reliable hot water, so don't have time on my side.


    Read more: https://www.******.com/diy/threads/...etecting-hot-water-flow.485642/#ixzz4n56sEQsv
  2. Jon Weaver

    Jon Weaver New Member

    Here is a photo of my cartridge.. I am not missing something? Its missing the Venturi yes??

  3. oz-plumber

    oz-plumber Plumber

    Well, why don't you just order the part, replace it and see if the boiler works.

    There could be numerous reasons why the boiler doesn't work - but you have found yourself a starting point.
  4. Jon Weaver

    Jon Weaver New Member

    Thats exactly what I am doing and have done (expecting the part in a few days).. But considering Baxi told me that "the boiler would not work at all without the venturi" and refuse to go into further detail, I just want to be sure I am on the right lines for such an issue as I MUST fix this in a matter of days. (Parents are late 80s and can't live there with no reliable hot water).
  5. townfanjon

    townfanjon Trusted Plumber GSR

    Sorry , no gas advice here pal , for the same reason as Baxi .
  6. Jon Weaver

    Jon Weaver New Member

    Ahhhh.. I am struggling to understand the law here... I get it if I was talking about the gas side. I would NEVER touch anything gas.. But this is pure plumbing.. If I am allow to install my own tap, or make changes to the plumbing, I don't understand why the discussions on the water side of the boiler are a no go.

    If I messed with the gas, it could result in death.. But the water side could only lead to damage and flooding (no different to if a tap leaked or I overfilled the bath).

    But if its the law, I will have to respect that and will have to carry on blindly and work it out for myself, which is surely more "dangerous"?????
  7. oz-plumber

    oz-plumber Plumber

    They're the choices you have to make for yourself.

    You could have called someone who most probably would have had the part available and repaired the problem on the spot.

    Your choice is to do the repair's yourself.
    You will be paying way over the odds for the part and it may or may not resolve the problem.

    But hey, who are we to judge
  8. Jon Weaver

    Jon Weaver New Member

    :) Over the odds.. So far its cost me 30 mins in time and a new Venturi is £12 (although I treated myself to a new cartridge for £15).. And I would be willing to bet thats cheaper than any plumber (or plumber supplies) would sell it for.

    Even if its the wrong part MY VENTRI IS MISSING, so its has to be replaced anyway, so even if it doesn't solve the issue and I have to get a plumber in, I have hardly caused a bigger issue or wasted time/money.

    The only reason not to do this is if I didn't have the tools/skills (Which I do), and the time (Which is my fault for leaving this long) And if it were dangerous, which it hardly is considering we are talking water.

    But I get the message. But I find it odd, as I found this forum due to similar requests for help for near identical problems and didn't get the negativity from those posts/replies.
  9. townfanjon

    townfanjon Trusted Plumber GSR

    Sorry Jon. I should have said , its not a well known fact ( it should be )
    Strictly speaking , you are not alowed to take the cover off . Sorry
  10. Jon Weaver

    Jon Weaver New Member

    Ah well, I am guilty as charged.. They had better lock me up, for my "crimes"..

    Message received loud and clear... I will just have to continue on my own and hope that the boys in blue don't come along any time soon (that was an attempt at humor by the way).

    For the record, I wouldn't be doing this if I didn't feel it was safe or I was competent. As an engineer with over 30 years in my field, I understand what I am doing and believe what I am doing is safe. I know my limits and I, for example would never mess with Gas...

    But lets leave this here and I will disappear from where I came

    Cheers all

    • Like Like x 1
  11. Chuck

    Chuck Active Member

    If you are an engineer with 30 years you will be aware that safety hazards are often not obvious. I think you'd be surprised at how much damage a hot water system with faulty or incorrectly set controls can do to people and property. At the moment you have a system that is failing safe. Think yourself lucky and get a Baxi-approved GSR to fix it in accordance with the manufacturer's instructions for you and let everybody sleep safely and well at night.
    • Like Like x 1
  12. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    @Lou@Lou close please

    Op as a gas burning room sealed appliance you need to be gas safe to take the cover off

    No ifs no buts
  13. Lou

    Lou Administrator Admin Top Contributor!!

    Down the well it is.
    • Like Like x 1
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