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ECM Giotto boiler water level probe depth and steam issue

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  • ECM Giotto boiler water level probe depth and steam issue

    Hi All,

    I have a 2006 ECM Giotto (Premium?) that I purchased about 9 months ago. When I first started using it the steam worked brilliantly and I was easily able to froth 300mL of milk without the pump kicking in. Unfortunately within a few weeks the machine flooded and tripped the house circuit breaker so I sent it back for repair. From what I can tell the pressurestat (Mater XP110), over pressure valve and boiler water level probe were replaced, along with the pressure gauge on the front (as it was very sluggish...). All has been working great since except for the milk frothing, which seems to have degraded (can't be certain whether it was like this from the repair or happened after). When starting to froth, the pressure drops down to ~0.6bar, then hovers there for some time and eventually drops slightly below 0.5bar when the pump kicks in, killing the steam pressure. Once steaming is finished, the pressure recovers quickly back to 1.1bar.

    When the machine is idle, the boiler pressure on the gauge sits around 1.1 bar, and shoots up to 1.2bar when heating which appears to be normal.
    After opening up the machine it appears that the new level probe is different. The new probe is inserted ~70mm when measured from the plastic sheath (where the red arrow is pointing).

    Original probe


    New probe


    I pushed the probe in ~5mm to lower the water level, purged some water and frothed 250mL of milk several times. This seems to have improved, the pressure drops and holds at ~0.6bar, but the pump doesn't kick in which is good.

    My questions are:
    1. During frothing on the Giotto, should the steam pressure hold at 0.6bar or should it be more around the 0.9bar level? As the first pressure gauge was very sluggish I didn't really notice what the behaviour was on the machine before it was repaired.
    2. What should the overall length of the probe be, and the insertion depth? I have looked at the replacement probes on coffeeparts and it is a 120mm probe, though this seems excessive and would drop the water level down lower than the heating element.
    3. Is there anything else that could be causing this issue?

    Any help would be greatly appreciated.

    cheers
    Dan

  • #2
    I'm no expert but I have exactly the same machine.

    My boiler cycle sits at 0.9-1.0 bar. When steaming it drops to ~0.8 ish and slowly descends during steaming but only to about 0.7 bar when finish a 250ml steam. Recovers pressure pretty quickly afterwards. I haven't measure the depth of my probe.

    I think you've found your issue already - I suspect it's just the ratio of water to air in the boiler. With the probe high (more water) there is less air to compress and therefore the pressure drops quicker as air escapes. Lower the probe gives less water, more air to compress and longer steam time, but careful not to uncover the element. In a perfect world the heating element will keep up with the release of steam, so you would see an initial drop in pressure due to the open valve, but then the pressure would remain constant.

    Comment


    • #3
      After spending some more time troubleshooting it appears lowering the probe didn't resolve the issue. It will still sometimes start the pump and dump the pressure below 0.5 bar without any obvious pattern indicating the cause.
      When the pump doesn't turn on during steaming, the pressure drops slowly from 1.1bar down to 0.6bar when the milk has reached 65 degrees and I stop frothing. At this point the pump will turn on. Once the pump has stopped, the pressure will go from ~0.6bar up to 1.2bar in about 47 seconds. Does this seem slow?

      I looked inside the boiler and it doesn't look great, there are flakes sitting on the bottom of the boiler. I'll descale the boiler with the heating element still attached on the weekend and see if that makes any difference. I'm not sure where to go from here though. Possibly the heater is on its way out and can't keep the pressure up?

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