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Mater pressure switch leak

Today I noticed water under my espresso machine and I found that the mater pressure switch is leaking water. What should I do to solve this problem?



  • Order new identical p-stat and replace is the simplest solution.

    Replacing it with the digital pre-infusion module is another option.
  • Thank you, Frans!
    I appreciate your reply!

    Is there a specific reason caused this?
    My machine is less than 2 year old and this is the 2nd issue I have faced so far.
  • Thank you, Frans!
    I appreciate your reply!

    Is there a specific reason caused this?
    My machine is less than 2 year old and this is the 2nd issue I have faced so far.
  • The little p-stat works hard. In my experience it's best to set it at one preferred pressure for the roast you most often get and leave it like that. If a p-stat like this is left for a long time and then one wants to change the setting, it might have lost its flexibility.

    But that is a very personal observation as I am not a routinely experienced tech service person.

    If one wants to change the pre-infusion pressure in a more versatile manner the digital module is the way to go.

    If you feel the upgrade would be above your tech savvy, then maybe sell your machine sometime this year and buy the current model that has it built in.

    And if you decide to order the new p-stat, order two so if it ever happens again you will have zero waiting time to replace and get up and running again.

    Plus piston rings and shower screen seal as these will come in handy, sooner or later.
  • PS addition: years ago when I talked to a professional espresso machine technician and expressed my surprise seeing these same small p-stats inside hugely expensive multi group commercial espresso machines, he explained to me that these were routinely replaced at every service visit to the coffee bar, preventing any leak. Of course in home use the machine does not work that hard and the small p-stat might very well keep going for years, but a replacement on occasion is not an exceptional event.
  • i agree with all frans writes above

    the static pressure of around 12 bar when the machine is at idle is what kills the longevity of the little Mater pressure switches, not the switching activity which occurs at 3.5 bar for the Mater

    durability is one reason why we have undertaken several years of research and development for the digital pressure transducer solution, which is designed to handle operating pressures of up to 30 bar

    kind regards

  • Thads pretty interesting. Anybody have an idea of how long we should expect the variable pressure remodel on the R to last?
  • hi brian

    im not sure i understand your post

    one of the reasons, apart from user adjustability, for moving to the pressure transducer is durability

    durability is the prime consideration in our designs because if anything fails prematurely we feel it in warranty claims

    the mechanical pressures switches did not enjoy the static pressure that is generated when the cold water introduced to the system expands, this increase in pressure being relieved at about 12 bar by the expansion valve at the top of the manifold, where it drains back into the water tank

    a pressure transducer is digital, therefore there are no moving parts and therefore it is not affected by higher pressures in the same way

    the pressure transducer we use is rated to work at pressures up to 30 bar, far beyond what can be generated in our espresso machine design

    the addition of the pressure transducer on 1 January 2019 represents a massive improvement in the durability x roast optimisation matrix for the LR

    kind regards

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