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Pressurestat Failure : Symptoms?

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  • Pressurestat Failure : Symptoms?

    Hi guys.

    Need an expert opinion on an issue I discovered this morning.

    Machine: ECM Raff megaline A2.

    I'm guilty of sometimes leaving this machine on overnight - never really an issue, except that means for about 6-8hours it is not being used.

    This morning I come up to make my usual early riser ristretto (yes, I need the kick to get functioning) and the boiler pressure is Zero.
    It's clearly stopped working in the small hours, as I went to bed around 1am and all was well. Normally I can hear the pressurestat relay clicking about every 45s-1min.

    I'm hearing nothing.

    I turn the machine off, then on. I get control relay click, pump click, and wait for pressurestat click and element rumble. No click no rumble.

    So I'm *thinking* the pressurestat has failed.

    Not sure if it's a Sirai or Parker or whatever.

    Before I go inside and pull it out, I have a couple of questions:

    1. Is it worth dismantling and cleaning the contacts in the relay, or would it be cactus?

    2. Is there a way to replace the magnetic relay with an SSR?

    3. Should I look for a different pressurestat - like a druck or something similar. (digital pressure transducer to control an SSR for the boiler element)???

    Not even sure that the last item exists for an espresso machine, but it could be fabricated.... but at what cost... who knows.

    I'm going to pull the p'stat and clean the contacts and pray this is a temp fix so I don't have to keep going up the road to get coffee over the weekend.


    Pulled the lid and the side off the machine, and took the lid off the pressurestat. everything actually looked pretty normal. Then I spied the thermal cutout on the side of the boiler.

    I pressed it and it clicked. Thinking this *may* be the answer, I powered the machine back on, and I started to hear the heater element creak into life.

    The machine came up to pressure after a while. It seemed like longer than normal, but I'm thinking it was likely that it was only my being anxious to test.

    Once the machine reached the pressure cutout, I heard the distinctive clunk from the pressurestat.

    To test the pressure drop and pressurestat cut in, I immediately opened both steam wands. The pressure dropped in the boiler very quickly.
    I shut off the 4 hole wand, leaving the twin hole wand wide open. Normally, the boiler can maintain about 1.1 bar with the wand fully open.

    the pressure was not increasing, nor maintaining any steadiness. just kept dropping.

    closed the steam valve off and waited . no pressurestat clunk.

    So it looks like the pressurestat is kaput.

    Given it's midday saturday I seriously doubt there is anywhere where I can get a new pressurestat from today.


    The only curious thing is why would the thermal cutout engage and cut the boiler element, if the pressurestat is failing to switch back on after it cuts out at the pressure setting?

    That is the only thing that has me confused.

    But if anyone here can help - ideas / advice would be appreciated.

    Last edited by JoeB; 5 April 2014, 11:57 AM.

  • #2
    Did the thermal cut out kick in again after the reset? Also does your ps have a replaceable diaphragm ?



    • #3
      pressurestat is a parker model. does not appear to have replaceable diaphragm. So will look for a sirai unit today. There is no clunk from the pressurestat when the machine is cold. only when it reaches temp.

      Thought about the thermal cutout switch. it's possible that it could be faulty, but doesn't really make sense. the boiler element must still be OK, because if it had a problem then it would trip the circuit breaker.

      So for peace of mind I'll grab a thermal cutout switch as well just to be sure.

      I am testing it again this morning to confirm.


      • #4
        Well, this is bizarre.

        turned on machine this morning after taking side panels off. click from control unit, pump filled boiler. waited: heats up. pressurestat cuts out. I leave it for 10 minutes, come back, and the pressure is maintained, the pressurestat working and it's still clicking away as we speak.

        I'm baffled.


        • #5
          update 2: The machine has decided to work without issues for the last couple of days. Quite unsure what the issue is, however I have a spare sirai pressurestat on hand, in case the world ends.

          The pressurestat is clicking on and off now, so I guess it was warning that the contacts might be getting dirty.