How old is the machine Gonzob?
My La Pav Pro has recently developed a problem. I think. Maybe.
In the past:
When I was about to prepare a coffee after heat-up, I would, as the instructions say to do, release the "false pressure" by opening the steam valve. This would pump out steam and the pressure would drop a little. I would then continue to make my coffee, and life was good.
I do the "false pressure" thing, and the pressure drops to under 0.5 bar. It takes a minute or so to get back to pressure. I continue to make my coffee, and life is still good. I thought, "aah, you're not waiting long enough for it to heat up", but waiting longer doesn't seem to make any difference. The machine performs fine after the initial start-up.
So, Is it likely that my pressure/temperaturestat is failing? Is it my imagination? Something else? Am I getting old?
If the pressure dropped only a little when you opened the steam valve then there was no false pressure, or you didn't leave it open long enough. If that were the case you'd know as soon as you went to froth the milk. The behavior you're seeing now is what is normally associated with having/releasing false pressure. Initially full pressure, then the release, and most if not all the pressure disappears. Then the boiler returns to full pressure taking some time to do so.
Java "Sounds like everything is fine" phile
Toys! I must have new toys!!!
Sounds like JP knows a whole lot more about the machine than I do, will leave it to him.
I don't know that specific machine at all except in a very general sense. But I do know physics and how boilers work passably well.
Java "Not blinded by Science" phile
Toys! I must have new toys!!!
Yes, JP, I agree with the analysis, however, it also occurs when I have not opened the filler cap between runs. So, it shouldn't be full of air, causing the "false pressure" issue. Unless, of course there is a vacuum release mechanism or maybe the air just leaks back in through the group...
Too much thinking...
Your machine is most probably fine. Was the boiler filled with the same amount of water as in the past? The lower the water level, the more false pressure there will be.
Some Pavonis have vacuum breaker valve, and some don't... If yours does have one, it means the valve is sticking (probably just needs a clean).
Part 19 is typically where the vacuum breaker valve is located. I have also heard some models have the vacuum breaker incorporated in the boiler cap (if this is the case you should see some spurting through the cap during warm up).
I have never felt it necessary to purge the little bit of air that might still be left in the boiler, but I do usually purge the steam wand to remove any condensation before I start steaming milk.
Mine have all been post-millenium models, but I think that LaPav started using anti-vacs much earlier than that.
Yes, well, there are days when you wonder why you got out of bed....
So, I HAD this problem, and thanks all for your suggestions. The problem has gone away.
My suggestion is DO NOT DO THE FOLLOWING:
> inspired by CS members suggestions, take a socket to the relief valve domed nut and turn
> the whole assembly now turns
> find a very thin spanner to stop the assembly turning (spend a lot of time running backwards and forwards to the garage)
> grind a spanner down because you can't find the correct one
> remove the domed nut and pressure relief valve
> discover that your machine has a vacuum vent valve
> clean it
> reassemble and test machine
> discover that turning the whole assembly has caused it to leak
> wait for the machine to cool
> remove the domed nut and discover that the assembly can't be tightened because there's a nut on the INSIDE of the boiler
> fart around until you find a spanner to fit the nut via the filling hole (yes, the filling hole)
> remove the assembly, clean it, reassemble it with sealant, and WITHOUT dropping the nut into the bottom of the boiler
> test the machine - it works!
> feel good
> look at the assembly drawing and notice that there is supposed to be a WASHER under the nut INSIDE the boiler.
> swear furiously, feel bad
> let the machine cool down
> open the top, and, using a torch, see the washer in the bottom of the boiler
> swear again
> disassemble the machine as above (twice previously)
> fish out the washer
> test - OK
At this point I realised that the problem was caused by SOMEONE ELSE filling the machine with water when she wanted a coffee. Unfortunately, the filling was usually only half-way, which (as mentioned above) leads to the symptoms I described earlier today when I should have still been in bed.
Thanks for your assistance
Sounds like Murphy paid you a visit...
Crikey Gonzo! what a saga, glad you got it sorted.