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L1 (2012) Pressure Issues

Hi Reiss and forum crew,

A few times over the past few weeks in the morning when I've come to make my first espresso I've noticed that if I put a bit of warm water in my cup and then tap the steam wand the pressure gauge goes right down to 0.3 or so. It's usually a lot higher than that. The group is hot though.

I just went down to make a coffee and it suddenly vented steam out of the vents (so must have been the relief valve) scaring the **** out of me! I turned it off, took the pressure right down with the steam wand and turned it on again and it's functioning normally but I'm guessing something needs replacing or a bit of TLC?

Thanks as always.


  • Aaron Bhavsar post=17058 wrote: tap the steam wand the pressure gauge goes right down to 0.3 or so.

    Possibly the anti-vac is stuck in the 'closed' = up position.

    If it is, when warming up the air sitting above the water in the boiler is not escaping out of the anti-vac and the air, warming up, creates the pressure that causes the pressostat to stop heating up further.

    Then when you release the air out of the steam tip, that's when the actual building up of steam pressure can begin and the pressure first drops to near zero.

    Vintage machines (like Pavoni) sometimes have that as a normal situation -- heating up with the steam valve open -- close steam valve after the air has come out.
    Aaron Bhavsar post=17058 wrote: it suddenly vented steam out of the vents (so must have been the relief valve)

    My guess is it's the same anti-vac, now stuck in the "open" - down position.

    If it's the OPV (Over Pressure Valve, a different bigger part) then you should be able to notice that when opening the top panel of the machine.

    Replacing the anti-vac is the simplest solution, in my view. Taking it out, taking it apart, cleaning any tiny debris causing the issue, re-assembling and re-installing is also an option.

    Reiss may have more / better input.
  • Thanks Frans.

    I'll see if Reiss can think of anything else to check out and try and give the anti vac a clan this weekend.
  • Something that may help is this: taking care at all times not to get burned by hot steam, use a pair of tweezers to move the little brass nipple of the anti-vac, pushing it down (steam escapes with a surprising power so beware), letting it pop up, and turning the little nipple clockwise or counter clockwise a few full turns.

    If there is just a tiny bit of sediment of scale preventing the full opening/closure or smooth up/down movement, this nimble gymnastics might rub it clean enough to fully close and open without getting stuck.

    Regardless of this, it may be a good idea to already order a replacement and add a set of group piston seals since in the long run you may need these anyway, and if/when you decide the anti-vac needs replacement, it's great to have one on your desk ready to go and swap and make coffee. Less anxiety of waiting for the part to arrive when it's already there.
  • hi aaron

    a machine of your vintage i think will have the 20A Sirai in it, which is why it is time to replace it, although now we use the 30A as it lasts much much longer

    if the safety has actuated, as your has, you need to replace it to

    and if you are getting the complete loss of pressure you report, as frans has already said it is the anti-vac valve, which as a matter of course you would replace at the same time as you replace the Sirai and the safety valve

    if the pressure gauge sits above zero when the machine is cold then you may want to replace that too if you want it to read correctly (this occurs when the anti-vac valve sticks and a vacuum is created and the needle on the pressure gauge it pulled back so hard against the stop pin on the gauge that the needle rotates on the axle of the gauge

    kind regards

  • & apologies for not replying sooner.
  • Many Thanks Reiss & Frans and no worries about the time taken Reiss.

    I'll pop the top this weekend and order the bits after I've checked everything out.
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