I just installed the new SMA vacuum breaker B.2.029 on my GS3 and am wondering at which temperature that new valve switches between open and close? The LM tech bulletin doesn't really talk about that point.
However I noticed when the machine cools down at the point where it shows zero steam pressure for a while, opening the steam valve actually sucks in air. Boiler is still hot to the touch where you could burn your fingers so most likely above 60C, but below 100C.
I am not sure if I like that. Anyone knows at which temperature the switch point is?

So it appears from this thread New La Marzocco GS3 Vacuum Breaker Installed (which it looks like I cannot reply to) that there are quite a number of people out there now with that new style vacuum breaker valve on their GS3.

I can't even tell when that new valve opens and closes (on the old one it was an audible hiss and change on the pressure gauge).
From that I assume it changes state somewhere below steam temperature.

My quick test to open the steam valve after the steam pressure gauge has returned to zero for a while (but the boiler is still hot to the touch) has resulted in the steam arm sucking in a bit of air, so at that point the old vacuum breaker would already be open.

It seems like a trivial question, but how do you verify that it does what it is supposed to do?

All the experiences I have read so far is people being happy about no dripping and no hissing associated with their new SMA vacuum breaker, which a simple plug would do too (arguably without the vacuum breaker function)

I notice a faint gurgle from the drip tray about an hour (just guessing here) after the machine shuts off for the night.
The pressure is zero of course at that point, haven't ever thought to turn the machine back on to check the boiler temp.

Good observation, Chris.
I decided to wait for it when the pressure reached zero, down from little under 2bar.
At 1 hour and 5 minutes after turning the machine off and without messing with it during the time there was this faint gurgle. Activating the steam valve after that event showed no response, there was no pressure positive or negative.
Next time I put a thermometer on it

I just removed the new SMA vacuum breaker valve from my GS3 because it failed after one year. La Marzocco and Voltage do not have rebuild kits available and no suggestions about getting on. So, I'm back to the old ref 'o' ring. I am however $100+ poorer and left with a not very substantial paperweight.
jerry

Hi Jerry,
can you elaborate a bit on how it failed? Did it start dripping or is it not closing or not opening anymore?
Thanks much for any info!