I have owned a La Pavoni Stradavardi Professional now for about 6 months. Initially I had no problems. At one point I think I was filling the water a little above the sight glass and since then I've been having two problems.

1. When I heat the machine up it builds up to 1 bar of pressure. If I want to make a shot of espresso I can with no problems. If, however, I open the steam wand the pressure almost always empties within 2 seconds, but then once it heats back up again I have long sustained pressure from the steam wand. I understand this may be caused by the stat (the pressure control system) taking a false reading of the pressure. But I'm not sure what to do to fix it.

2 My second problem is that occasionally - maybe 1 or 2 times out of ten - when I turn my machine off, after it cools for half an hour or so, the lever on the machine mysteriously lifts itself to the highest position and stays there. This is very confusing to me, because I could understand if there were a vacuum on the top of the piston pulling it up, but as far as I understand it, the vacuum would be coming from the side of the piston from the inlet to the boiler.

Any help would be appreciated.

On the pavoni , the inlat hole is ABOVE the piston
so any vacuum would try to rise the lever , if the piston runs smooth , the lever will rise , its a good thing

The so called false pressure is not false , but its a mix of air and stem . mostly air
air can be compressed ,
as the air heats up , the pressure rises
when the pressure reach the setpoint of the pressurestat , , the heating turns of

when you bleed of the air its quickly gone
the water has NOT reached boiling point
that why there is no steam


NOW the water is heated to a temperature way over the boiling point at NORMAL atmospheric pressure
the water will keep heating up , following the lows of nature (higher pressure =higher boiling point)

when the pressure reach the setpoint of the pressurestat , , the heating turns of

if you now opens the steam wand ,steams comes out , but at the same rate new steam comes from the super heated water , and the heating element can keep up with the loss of energy in the water

Thanks Cmtwgr.

I've not heard of anyone else having this problem with the lever lifting after you turn it off. Also, my understanding is that the top (side) of the piston covers the inlet.

Also, I'm still looking for a fix for the pressure problem in the boiler. I know that if i release the pressure from the steam wand then it will build up to proper pressure - but the machine is only a year old and it should build up to the proper pressure right from when i turn it on.

Some newer Pavonis have a safety valve that also has a vacuum breaker built into it

I dint know if yours have such thingy ;o)
but any machine that doesnt have a vacuum breaker (or a stuck one) needs the false pressure bleeding off

bostonbuzz - I was unaware, thanks.

Cmtwgr - its only a year old and I'm almost certain that it does have a vacuum breaker in the same place as the pressure safety valve - and i guess its stuck, but i'm not sure how to get it unstuck.

The strange thing is that you started having this problem without any modification to the machine.
In my opinion this could means that your safety release valve is stuck in the part related to the vacuum breaker (the smallest piston in the valve)
If you have had this problem from the very beginning, I would have said that your machine is equipped with the plastic mushroom valve, that has not vacuum breaker.
alberto

Here an image of the two different safety valves
The right one is on the right hand side
In that one, the smallest piston have the vacuum breaker function
You should check if it can move or it is stuck
alberto

my LP pro will lift the lever like that for a while after I clean and service the piston and seals. it surprised me too the first time. I figure this just shows that the lever/piston move easily. that is a good thing. it means things are clean and not gunked up. as to the "false pressure"... that is a well known LP quirk. it is easily overcome (and I believe speeds up the process of getting the machine up to working temp) by just opening the steam wand and pulling a small shot of water into a cup at the same time. the added benefit to this is that if you leave the water in the cup till you are ready to pull a shot, then you will have a warm cup.

bostonbuzz wrote:It will not build up to normal pressure without a vacuume breaker. Sometimes if the lever doesn't go up to release the pressure, you have a vacuume in the boiler until you turn it back on and you don't have to bleed any false pressure.

I don't understand what vacuum is supposed to be broken, or how the 'breaker' works. I sort of understand why air compressed by pressurised steam in the boiler can trip the p/s when the steam pressure is not high enough to do so, which is why the air must be bled off. But how does a vacuum come in to the picture? The boiler, after all, is filled with water, steam and air. (As you can see, I'm no engineer; but I am curious.)