La Pavoni False Pressure and Lever Lifting Mystery - Page 3

#21: Post by **yakster** » December 23rd, 2013, 4:33 pm

Glad to hear you got it working.

Muffin pans are good for organizing small parts. I was even using them for a while for sorting coffee defects by type.

#22: Post by **hankbates** » December 23rd, 2013, 4:54 pm

rpavlis wrote:Some people make fun of me when I work on various things with small parts like microscopes and espresso equipment because the very first thing I always do is take a large all white soup bowl and sit it by the equipment on which I am working. When I am working with something that has many small parts I usually put an old white bed sheet on the floor and set the equipment in the centre of the sheet, and the soup bowl by its side. By working on the floor I avoid the problem of having things fall and bounce to places where they may never be found again. Even tiny parts are visible on white bed sheets.

Then as I remove parts I put them in the soup bowl. Sometimes when there are sub assemblies to disassemble I get a white cereal bowl and put the parts of sub assemblies in that to avoid confusion. When there are several sub assemblies I use more than one cereal bowl. Keeping things white makes the components easier to locate.

Boy, can I relate to this. Especially the part about bouncing parts which disappear.

#23: Post by **Cmtwgr** » December 24th, 2013, 2:56 am

If things can go flying , taking them apart inside a clear plastic bag , is sometimes a good idea

#24: Post by **mathof** » December 30th, 2013, 1:41 pm

homeburrero wrote:The anti-vacuum is a little button dangling below an orifice with a rubber seal. Gravity opens it, and escaping steam forces it up against the seal, where it is held closed by boiler pressure. When the pressure inside the boiler drops to atmospheric the little button drops down, opening the valve to outside air. Same principle as the button in a pressure cooker.

The reason you don't need to worry about bleeding 'false pressure' when you have a working ant-vacuum is because as the machine warms up and is producing water vapor, the AV valve is still open, allowing steam and air to escape through the valve. By the time enough steam is being generated to lift and seal the valve, all the air has been driven out and replaced by water vapor.

Hello, Pat. I ordered from a UK supplier an LP Anti-Vacuum valve and spring, which arrived today. However, when I have tried it, the valve simply omits a great deal of steam as the boiler heats up and continues to do so until I switch it off. The boiler pressure levels off at about 0.2 bar. I tried the sharp rap technique, but that made no difference. The valve couldn't be scaled up as it's brand new.

Any suggestions would be appreciated.

#25: Post by **algue** » December 31st, 2013, 3:56 pm

I think that the problem could be that your new valve is not compatible with the part of the valve screwed to the boiler.
If I remember well from spare parts data sheets, that sort of nut also is different between machines with or wihout anti vacuum valve.
I suggest you to ask to your dealer.
From what you are saying it seems to me that your valve can't close, probably because the shape of the two parts does not match.
If this was true you should see at the beginning lot of steam when manometer is at 0 pressure (this is the anti vacuum part working). Then you should see steam stopping and pressure starting to raise up to 0.2bar. At this point tou should see steam starting again due to the leaking of the valve.
Bye
Alberto

#26: Post by **mathof** » December 31st, 2013, 4:12 pm

Thank you, Alberto. That is an exact description of what happens, and your diagnosis is the same as my dealer's. I have ordered the replacement parts that I need. I'll report back when/if I get it working.

December 31st, 2013, 11:03 pm

algue wrote:If I remember well from spare parts data sheets, that sort of nut also is different between machines with or wihout anti vacuum valve.
I suggest you to ask to your dealer.

mathof wrote:Thank you, Alberto. That is an exact description of what happens, and your diagnosis is the same as my dealer's. I have ordered the replacement parts that I need. I'll report back when/if I get it working.

.. just now got back to this thread. That is interesting, news to me - and important to anyone considering adding this AV valve to a machine that does not already have that valve. I went back and looked at the factory parts list, and it does appear that the parts numbers changed on both the casing and seat when they added that AV valve. I assume this is what you ordered to go with the new valve and spring: http://www.espressoservices.co.uk/39675 ... e_cas.html

Good to know about that wrinkle.