La Pavoni Europiccola Post-Millennium safety valve question

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
maki

#1: Post by maki »

never owned or worked with a Post-Millennium. should steam always come out of the valve as in Pre-Mill or is this an issue with this machine?

a friend of mine inherited it and asked me to take a look..
LMWDP #630

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homeburrero
Team HB

#2: Post by homeburrero »

Something is amiss. On the newest machines there should be a slight hiss from the anti-vac valve for a few seconds when the machine just starts to come to pressure, but after that it should not continue to hiss at all. On older millennium and late pre-millennium with pressurestats which don't have an anti-vac valve you should have no hissing there at all unless the machine heats up above the safety pressure (above 2 bar or so.)

If the safety valve is continuously releasing pressure from the time that the machine begins to get up to pressure, then it's probably stuck open or failing to seal. If so you need it inspect and clean or replace it.

I notice that your green light appears to be unlit, and it should on whenever the machine is heating. Perhaps the lamp is bad or the wiring to the lamp is bad or disconnected. But I also worry that maybe something is dangerously miswired so that the pStat is not shutting off the element, and the boiler is heating uncontrolled, causing the safety valve to release the too-high pressure per design. I suggest unplugging and verifying that the wiring is correct.

Here's a diagram that might help to understand how it should be wired: userpix/10510_pavoniep-millenniumwiring.png
Pat
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maki

#3: Post by maki »

thank you for detailed reply!

yes, indeed you are correct- the green light was off as the safety thermostat shut off the heating element, as pStat seems to be stuck on.

well, that's a challenge but after refurbishing my Pre-Millennium i think i can handle it.

inspected the pStat, it's a model with a ring on it, i suppose it's where you adjust your pressure. rotated it - no changes.
next though- the tube can be clogged with scale, as machine was not taken good care of. do i need to take the tube off or a simple descale process of the boiler itself should take care of the scale from pStat tube?
LMWDP #630

maki

#4: Post by maki »

this is my wiring, seems like it's correctly wired.
LMWDP #630

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homeburrero
Team HB

#5: Post by homeburrero »

maki wrote:next though- the tube can be clogged with scale, as machine was not taken good care of. do i need to take the tube off or a simple descale process of the boiler itself should take care of the scale from pStat tube?
That's a very likely cause. What most people do is remove the pressurestat from the tube, then get in there with a wire or pipe cleaners to remove the clog. It's better not to remove the pipe from the boiler because that fitting is sealed with a threadlocker, so if you remove it you need to put it back with a threadlocker.

Once it's all back together you can do a final mild descale, cycling up to pressure a few times to encourage getting the descaler down into the tube and pStat. 50/50 white vinegar and distilled is recommended over citric acid for this, followed by a very thorough rinsing. (In theory, citric acid might leave behind a calcium citrate sediment that might settle down in that tube. Vinegar gives you calcium acetate, which won't precipitate, but the vinegar leaves a strong odor that you need to rinse away.)


P.S.
Wiring looks correct to me. The tripped thermoswitch explains the green light being off in your video.
Pat
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maki

#6: Post by maki »

just finished assembling it back. again you're correct - it's the tube that was clogged. cleaned it, as well as the pStat itself and now it cycles wonderfully at 0.8-1.0 bar.

one more question if i may- what's the best range for this machines?
LMWDP #630

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homeburrero
Team HB

#7: Post by homeburrero »

maki wrote:one more question if i may- what's the best range for this machines?
The current factory spec says 0.7 - 0.8 bar so I think you're OK. Higher means that you'll get a little better steaming and your group will be a little quicker to overheat. At higher elevations you can go higher in pressure -- at 1000 meters above sea level you can go 0.8 - 0.9 bar gauge pressure and have the same temp as a machine at sea level at 0.7 - 0.8 bar.
Pat
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