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Group Head- three way solenoid valve body has a hole in it ???

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  • Group Head- three way solenoid valve body has a hole in it ???

    Working on my machine and one of the group head three way solenoid valve body has a hole in it (see image below) and I am not sure if this makes it un-servicable?  

    This group did not work when I got the machine, but I am 99% sure that is electrical.

    I (sort of) know how the solenoid works with this valve, but am unsure if this part with the hole is supposed to be water tight?

    The other group head is fine, but they are different as in one or the other has been replaced over history.

    I can get a new part but if this hole is common in some units Id prefer to save the money.

    Any thoughts on if this hole is a locating mechanism for a solenoid, or do I need to replace it?

    Thanks as always for your consideration.  Cheers, Colin


  • #2
    Re: Group Head- three way solenoid valve body has a hole in it ???

    Pretty sure thats an undocumented feature. Id replace.

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    • #3
      Re: Group Head- three way solenoid valve body has a hole in it ???

      Cactus - needs replacing. The way these valves work means there will be heated pressurised water behind that hole every time the group is activated. And what tends to happen when water gets in between the valve body and the coil is that the coil shorts and burns out, sometimes even partially melting. I reckon that holes probably the reason that group doesnt work (3 way valve is probably dead).

      FYI, the way these valves work is that when the coil is energised, it creates a magnetic field that pulls the internal plunger in the valve down against the spring that normally holds it shut. The plunger has a seal at the top and at the bottom. When off the top end seals and shuts off the water supply from the heat exchanger to the head while also connecting the group head to the drain outlet - when you activate the group, the plunger is pulled down, opening the valve and letting water flow from heat exchanger to group head, and at the same time closing the drain outlet to stop water flowing out the drain. When it shuts off, the plunger springs up and stops the water flow from the heat exchanger, and at the same time opening the drain outlet so that water pressure in the head is released. This is the important trick these valves have up their sleeve - a regular 2 way solenoid valve would do the job, except that it wouldnt release the head pressure. So unless you leave the handle in for a while to allow the pressure to seep past the coffee puck, taking the handle out would release the pressure by spraying wet coffee everywhere from the handle!

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      • #4
        Re: Group Head- three way solenoid valve body has a hole in it ???

        Thanks MorganGT. Nice explanation of the operation. I will add a new sleeve to my order list and test the solenoid incase it needs to be added as well.

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