Ok, I would like to start by apologizing. I'm sure I can find my answer already spelled out somewhere on this forum. Please direct me if the topic already exists.

So, I recently bought a brand new La Pavoni Professional in chrome. Within a week of owning it, I have had great success, loads of crema with zero bitterness and lots of accenting flavors. A few weeks later I bought a used brass/copper professional (pre-millennium - 1997). The problem I am having is heat related. With the new one, the first 2-3 pulls are a nice temp and then I use the common methods of cold towel and soaking the pf to cool the girl down, no problems, works like a charm. The very first shot on the used machine is very hot, to the point that its bitter and will burn my mouth. Any ideas, am I doing something wrong?
Thanks in advance,
~Nick

Even though they are both pro models (with pStats), the millennium and pre-millennium are thermally different because of the group. The pre-M has a vent/channel between the top of the group cylinder and the boiler. Some call it steam heated. There is no vent like this on the millennium group.
Also, your pre-M has no cylinder sleeve, so the brew water feeds straight from the boiler into the brew cylinder via the siphon tube. The millennium is a sleeved design so much of the water that feeds your brew cylinder has been sitting out in the cooler space between the group and the cylinder sleeve.

If you are walking up and pulling a shot from an idle group that has been on for a good while, the pre-M should be hotter. The two machines may need different approaches to managing group and brew temp.

I'll share a brief description of my method as one example that works pretty well for me on both machines, for first shots after turning the on machine as well as for subsequent shots in a session:
I always start with a too cool group - If the machine has been in use, or on long enough for the group to have gotten hot, I always cool it way down (nowadays I just use a cool wet bar cloth for this.) Then I half pump (and flush a little) to bring the group temp up where I like it immediately before pulling the shot. I use 60C-90C temp strips - have learned to fairly precisely read my group temp by watching the subtle color changes of the patches. (Won't work if you have old strips or poor lighting.) The "where I like it" point is based on experiment and taste. I may also fudge the temp a little by turning the machine off and brewing at a slightly lower than usual pressure, then flip it back on for steaming. (I don't leave my Pavoni turned on between coffee-making sessions.)

I should mention that many people find temp strips inadequate and prefer digital thermometers attached to the group. Others get by fine with no thermometry - have just learned to get the timing right between switching on/off and pulling shots. On the millennium you might be able to leave it on for hours, and pull a good shot from idle with no attention to group temp.

neeko1118 wrote:Ok, I would like to start by apologizing. I'm sure I can find my answer already spelled out somewhere on this forum. Please direct me if the topic already exists.

No need for apology. I know if you search the site for Pavoni and Temperature, the hits would be overwhelming. There is a lot of great info, here are some threads that I think would help:

La Pavoni Millennium Owners, Are Temperature Problems Solved?
Adding Thermometry to a La Pavoni Europiccola
Second pull on La Pavoni Europiccola is too hot - is pressurestat too high?
Bought a new La Pavoni Europiccola and want to learn
Tips for Controlling Brew Temperature on a Home Lever Espresso Machine

The best approach to reduce the level of frustration is to treat these as entirely different devices. I have a 97 pro machine and the process I use is similar to what homeburrero posted.

I first grind beans then turn on the Pavoni with at least 1/2 glass of water in it and allow pressure to build to 1/2 bar or slightly above. When at about 1/2 bar I vent through the steam wand until I get a cloud of water vapor, this is a long blow down. Then I allow it to come to the point of P-stat shutoff while I build the puck. The coffee is 15gr in an Elektra double basket with a 10lb tamp to get head room. Once puck is built I again blow down the boiler until the catch container gets hot and when vapor cloud fogs my glasses. Now I allow the pressure to build back to P-stat shutoff, this is maybe 30 seconds. Lock in portafilter and raise lever and hold up until group completely fills and puck preinfuses, several very light and short pumps will accelerate this process. Pull shot using about 30 lb of lever force and a 15-25 second pull time. Raise lever and repeat for the fist double of the day. I turn the machine off just as I start the first pull and leave it off. I turn it back on again as I build another puck for the 2nd double of the morning. This keeps the group from becoming so hot that the results are less than satisfactory without recourse to drastic cooling measures.

You will have to come up with your own routine for this but there is minimal steam heating of the group until all the non condensible gases are vented out as the machine heats up. Until vented off the only heating is primarily conduction from the boiler. Careful feeling of the parts while heating will confirm this without recourse to extra test equipment.

I just have to echo that the mil version is just do dang easy to use. I have been continually impressed by how simple it is, much different than the reports on the pre-mil options.

Thanks to all three of you for replying! I tried pulling a shot today. I started it and let it come to .5 bar. Released pressure through the wand for a good amount of time. Let the pressure come up to the point that the machine cut power right around 1.0 bar. I felt the group head and it was only warm. I Pulled the shot and it still came out very hot. Is it possible that the pressure gauge is inaccurate? I understand that this is a more temperamental machine; however, is it possible that it is this hot right from the start?
~Nick

That first pull will be probably 195 - 200F water. Do not for get to vent when you reach 1 bar as there is still some noncondensible gas in there. At this point you can change grind, tamp pressure, and pull time to get what you want. Nominal pull time is 15-25 seconds with 30lb on the lever. The time with the group full and the lever held up lets some heat in the water transfer to the group which results in cooler water in the group. The water that initially enters is directly from the boiler and will be rather hot. When you raise the lever hold it up until when slightly lowered it feels solid and repeat this move until you get a drip out of the PF. If it promptly runs out then the grind is too coarse or the tamp too light. Generally better luck is had with a light tamp. This is one of these man over machine types of things to get it to work.

neeko1118 wrote:however, is it possible that it is this hot right from the start?
~Nick

The Pre-Millenium, post 1973, models are hot little monsters. Without a thermometer to gauge some group side temps you'll be guessing constantly. I put a digital thermostat on my Pre-Millenium, spent alot of time guessing how to pull right on that thing, finally found a method that worked for me and just stuck with it. When my La Pavoni comes up to temp after 10 minutes I pull my shots, cool the group if necessary and pull another, steam my milk and shut it off. Also, don't put your PF in the group when heating up on the pre-millenium. You don't need it and a cooler PF will also help to cool the group just enough to give you a good pull.

Drgary on the other hand has/had a Millenium model and it sounds as if his setup with some temp monitoring is just as easy as you found your Millenium model. He's spent alot of time documenting his La Pavoni methods and testing here on the forums and I found his information quite useful even if it was for a different model in the series.

Rpavlis I think has Pre-Millenium models, and his method is slightly different. Again, great information from him on the product.

neeko1118 wrote:I felt the group head and it was only warm. I Pulled the shot and it still came out very hot. Is it possible that the pressure gauge is inaccurate?

Normally is not likely, but if you're getting overly hot shots when the group is only warm to he touch I would not rule out the possibility that the gauge is reading low and that someone then adjusted the pStat up to match the faulty gauge. Try switching it off, letting off a little pressure, and pulling shots down around 0.6 bar and see if that helps. You can always lower the pStat setting - just don't go so low that your steaming suffers. According to Francesco Ceccarelli, the factory setting on these in the late 90's was down to 0.6 bar -0.8 bar in an attempt to deal with user complaints about hot temps.

There is no vacuum relief and the needle will move the shaft if pulled negative far enough. A temp gauge on the steam wand or as this is a saturated system once all noncondensibles are vented off you can check external boiler shell temperature and compare to saturation pressure. psia - 14.7 = psig, -a is absolute and -g is gauge reading. Link is absolute pressure vs. saturation temperature and 1 BAR is about 250F. http://www.engineeringtoolbox.com/water ... d_599.html This will be the easiest way to validate the gauge.

OldNuc wrote:There is no vacuum relief and the needle will move the shaft if pulled negative far enough.

Yes, and that will shift it so as to show a pressure that is erroneously high, and the needle will show an above-zero pressure when the machine is cold. I think the suspicion here is the opposite - that the machine is showing 1 bar when the actual pressure is 1.2 or something. Not likely, but perhaps worth looking into.

Since the OP has two machines, one option to check the suspect manometer would be to temporarily put it on the newer machine and see what it reads.