Hi folks!

First time poster, and recent purchaser of a used Pre-Millenium (man. June 1995) La Pavoni Professional that has a super clean heating element. This was a major upgrade from my first machine so I'm pretty pumped

However, I'm a bit confused about my pstat and am hoping for some internet wisdom concerning it. My machine tends to hover around 1.1-1.4 bar according to the gauge, and my understanding is that if I lower the pstat setting I can lower the overall temperature of my boiler slightly. I'd like to do so because steaming isn't a priority for me, and the heat on this thing seems a tad.... Violent....

My problem though is that my pstat doesn't seem to be like the two pstats I have seen in this forum so far,and my attempts thus far to adjust the pressure seem to have heard no affect on the pstat. Here's a picture.



Hopefully this is clear enough for some troubleshooting. You can see that there is a brass flat head screw pointing from the left of the image to the right, towards the pstat. I've tried turning that screw both ways a pretty good distance up and down, and it didn't seem to adjust the pressure threshold at all....

But I don't see elements of the pstats that I've seen in other posts. No set screw, no dial to turn.

Any ideas?

I tried removing the screw to see if I could get any clues, and this is what I found.... (note that the orientation of the image has changed.)



And it seems that the writing that I couldn't see before due to lack of lighting is implicating that this IS the control. The unfortunate conclusion that I've come to is that loosening it lowers the pstat threshold, and that tightening it increases it. And I think I've already given it a shot at its lowest setting.... But I'll give it a shot soon here.

Well, sorry to triple post. I'm playing forum solitaire here. But I tried screwing the screw in farther than I was previously comfortable, and it definitely raised the pressure threshold. Unfortunately, loosening the screw basically all the way doesn't lower the pressure threshold from the 1.25 average.

So it looks like I can't even lower my pressure below that point. This is disappointing.

My monologue is over. Hopefully this is interesting.

La Pavoni never used branded MATER pstats so this is a replaced part. The MATER stat is known for its fail rate, for whatever reason..generally said to get waterlogged, and installing in this position under the boiler would likely point to this. If turning the screw out all the way does not change the high limit then the pstat is not working due to diaphragm problem, scale, or just bad luck. That it turns on and off means it IS working but that you can't adjust it means something is wrong with the stat.

Wow. No longer a monologue but a response by the lever guru himself! One of the first places scale can cause problems is in the PSTAT. You may find it is getting scaled. To test and hopefully solve that, see if you can remove it, seal it, and introduce some droplets of 50/50 solution of white vinegar into the water pipe end. Let it sit for an hour or two. Use the vinegar solution instead of citric acid because the vinegar won't precipitate into different solids that can still block the small passages inside the PSTAT, preventing it getting triggered soon enough to turn off the heating element at a lower threshold than you're getting now.

If none of this works a PSTAT is easily replaceable and not too expensive.

Thanks for the tips, sirs!

I've ran into mentions of that vinegar method before, so perhaps I'll pull the pstat, see what my amateur eyes can find, and perhaps give it a go.

Is it at all possible that this pstat never was able to adjust below 1.25 bar? Just thought it was worth asking since it seems to adjust above 1.25 just fine, but not below it.

Where does one buy a replacement pressure stat for one of these things? You don't happen to sell them, do you, Doug?

I already picked up some lc thermometers from you and am excited to get them it. Thanks for carrying them! You're the only one I saw.

The model designation XP-GP is not familiar...current MATER used is 110 XP....so it is possible that the GP part may mean high range or something. We don't stock many electrical parts anymore but it is a common part. May want to consider a CEME as well since the CEME is used in a lot of under boiler applications and is a little smaller in diameter if fit is an issue. On the other hand if you use a MATER the micro switch is useable from the old one.

I remembered you don't need to pull the PSTAT. Use the 50/50 vinegar solution and power cycle the machine on and off about half a dozen times. It'll come up to pressure, forcing vinegar solution into that small passage. Then you shut it off, power on again and bring up to temperature for the same result. That has worked for several machines for me. If that doesn't work swapping in another PSTAT shouldn't be hard, and they all come with microswitches attached. Ask Doug if he carries the correct replacement part. But you're not there yet. Try the vinegar descale and you may be good to go.

Stefano's Espresso Care sells adjustable PStats

http://espressocare.com/products/item/a ... -la-pavoni

You could also preheat the vinegar, white distilled, and use pure concentration, let that sit for a while, pour some hot water in to dilute a bit , run the machine to get some pressure and the turn it off- if the 50-50 ratio doesnt work.