La Pavoni Professional pressure gauge failure

[orwa]

Hello everyone,

I am pretty busy in my Master studies at the moment but I cannot neglect the signs of failure I am currently noticing on the relatively new pressure gauge I have on my Professional. When I first bought the machine it was used for around 13 years, with a burnt brown fuse and mountains of scale inside the boiler. I started using the machine by descaling it and bypassing the fuse in the electrical system, then I used a non-resettable fuse that I was able to find locally. After this I kept using the machine for maybe 4 months until the pressure gauge had a sudden failure. I admit that immediately before the failure I left the machine on for a couple of minutes (maybe five) with the boiler cap off while on, which resulted in the machine working as a kettle for a while. This MAY be one (if not the only) cause of the failure of the pressure gauge. Anyway, this made me buy a set of new parts for the machine replacing every functional piece in it, and buying a new portafilter (I even replaced parts that people don't usually replace like the lever pins and the C clips). Today after maybe 4 or 5 months of usage after the rebuild, the zero point of the "new" pressure gauge is having a constant offset towards the positive side: it started by shifting to 0.1 bar at rest, 0.2 bars, and today it's nearly 0.25 bars at rest... Ain't that frustrating?!

To give you all the details of daily operation, I am admittedly an aggressive user of the machine. I operate the machine sometimes 3 times a day, each time brewing two double shots and frothing from 1 to 3 amounts of milk, where I had short periods of intense operation where I did things people usually don't do on the Pavonis, namely when I went with my parents to meet the big family in Jeddah last week (1400km from my place) and took the machine with me. When I was there, it happened that I made around 20 drinks in a 2-hour session (splitting every double shot into two bases for two macchiato-size latte-milk drinks), where at the end when I was tired of emptying and filling the machine I used to stay at the frothing pressures for extended periods (30 minutes?) and froth for many chocolate latte drinks for the "little ones".

I must also say that I froth at 2.0-2.5 bars of pressure with a 3-hole acorn nut tip as this was the only way I could reach a microfoam that is up to my taste. I have a feeling that this unusual practice is related to the smaller gauge of the wand when compared to the thick wands found on the HXs and the commercials (which operate at a much lesser pressure and still do well) which may give a reasonable justification of why I wasn't able to obtain good milk using a less aggressive type of operation (lesser boiler pressure/temperature).

I hope that you may be able to help me as what to do to prevent future failure of the pressure gauge or as to understand what is happening precisely. The image I am currently having in mind is that the Pavoni is a crappy machine that just gives the impression of a reliable horse but in fact isn't, and that it shouldn't be used the way I am using it (operating the boiler at those high pressures). But for god sake, why is the whole range there on the pressure gauge if reaching it would cause that amount of rapid destruction? The La Pavoni pressure gauge is VERY expensive and I am not willing to buy another one, especially that La Pavoni has no existence in my country and thus I will have to request it from outside, incurring a considerable increase in the cost, and in the delay (don't tell me about the delay, I kept waiting for the stupid gauge for 3 whole months!!).

Thanks

[r-gordon-7]

Well, orwa, I'm probably a much less aggressive user of my Gaggia Factory 106 than you are of your La Pavoini Professional, but my understanding is that the two machines share the same basic pedigree and that many of the parts are essentially the same. Although I don't know if this is the case with respect to the pressure gauge, the gauge on mine has never come to rest on the pin at zero. It always comes to rest at ".1", that being the second hash mark above the pin. The needle rests there even when the cap is off, so clearly it is simply a presure gauge that has been slightly misadjusted "since birth"... As the gauge on mine has not shown any change in its point of rest since I first received the machine several months ago, I figure I can live with it that way. However, if yours keeps coming to rest at increasingly higher rest points, it would seem that there's more to the story than a simple misadjustment - but it sounds like you already suspect this is the case.

r-gordon-7

[orwa]

Yes gordon, I am sure that the resting point is continually rising, and that it's happening rapidly, mine started resting nearly at the pin, then at the first hash (that being 0.1 on mine), then at the second (0.2), and now, believe me it looks to rest in-between the second and the third hash (around 0.25 bar)... All with the boiler cap off. Moreover, when I first replaced the pressure gauge I remember that I had a very strange feeling, a feeling that the same pressures I used to experience previously are suddently being logged "lower" by the new gauge (not mentioning that the older gauge was marked differently, and that it was much more beautiful with a thoroughly golden casing rather than a black-plastic casing with a golden frame. The green region on that older gauge was also considerably wider than the new one, extending roughly to 1.5 bars).

I would like also to add that my wooden boiler cap has a number of cracks in the wooden shell and is suspected to have minor leaks, which may cause the machine to heat up unnecessarily when operated under high pressures for extended periods (I don't hear any hissing sound though). The boiler cap on mine is not thorougly in wood like the one photographed on espressoparts.com but is basically metallic with a wooden shell (the 14-year-old golden model I believe, with the group wholly in brass and no plastic anywhere, neither the piston, the group-boiler interface cake, nor the boiler flange are plastic. Mine also has the old copper heating element whose gasket is nomore manufactured and the old OPV mechanism with the metallic ball and the hard spring, which noticeably tolerate higher pressures than the new ones -I used both on my machine and with the original one I hear no hissing even at pressures as high as 2.5 bars!).

[zubinpatrick]

relax......your pressure gauge is a mechanical spring device. It is not failling just out of calibration. You can still make coffee and should be able to adjust yourself to the inaccuaracies of the gauge. Also you are asking alot of a home machine, drive anything hard you will need to do more maintenance. The pressure gauge has has not failed it is jsut out of adjsutment. How hard is the water where you are? When was the last time you descaled? After the previous PG failure did you examine the gauge? WHat exactly was wrong with that one, was it repairable? Also if you want any PG can adapted to fit your PAV, refrigiration parts store etc shoudl be able to get you a more accurate higher quality PG. re: the boiler top, if its not leaking it's not leaking, suspecting it of leaking as the wood cracks (wood cracks it's wood) does not mean it's leaking. If it is leaking you will know, it will swell with moisture etc...I don't have the wooden top but I'm pretty sure it's decorative and the base is still plastic/bakalite/whatever...good luck with all that...Patrick

[orwa]

The original gauge had a true failure, where some permanent change has occurred to the coil inside of it, resulting in a gauge that can hardly log 0.4 bars even when the pressure is as high as 1.5 or 2.0 bars. It also developed noticeable dependency on the temperature, so that when the machine is very hot the pointer of the old corrupted gauge would rise, and would not fall again to zero after the machine is turned off and all the pressure released, but would only do so when the machine cools.

I agree that the boiler cap probably isn't leaking... Either it leaks, or it doesn't, and when it leaks I must be aware of it (I believe the wood would smell in that case too). In my case the base isn't plastic, like I said none of the parts of my Professional are plastic, it looks like machined stainless steel (cannot be anything else with the metallic colour in that corrosive, humid position, can it?).

I tried to look for alternatives (of the gauge), and I visitied a plenty of these shops in my place. The problem is that they use the American pipe thread and hence I will need to machine an adapter, most probably similar in position and function to the already-existing nut that plugs the gauge to the top of the sight-glass assembly on the Pavoni's. However I must admit that though these look to be of higher quality (needle more sensetive and movement is smoother), they are too ugly to mount on a "golden" Professional... But I will do it nevertheless if I was unlucky enough to have another ruined gauge.

[TUS172]

Excerpt:

I tried to look for alternatives (of the gauge), and I visitied a plenty of these shops in my place. The problem is that they use the American pipe thread and hence I will need to machine an adapter, most probably similar in position and function to the already-existing nut that plugs the gauge to the top of the sight-glass assembly on the Pavoni's. However I must admit that though these look to be of higher quality (needle more sensetive and movement is smoother), they are too ugly to mount on a "golden" Professional... But I will do it nevertheless if I was unlucky enough to have another ruined gauge.

Review the thread below... A little research and 'elbow grease' will solve your problem...
McMaster Carr has a number of high quality gauges and NO you do not have to machine anything... McMaster Carr has them in stock in stainless steel.

also this site has a number of gauges... perhaps with the thread you need. http://www.cafeparts.com/dynamicIndex.asp

help-what-is-thread-size-of-la-pavoni-pro-pressure-gauge-t6171.html