I've heard this mentioned here and there. What is it? And why is it so special and desirable?

Here's an explanation with pictures:

3-Way Valve Hows and Whys

The short answer is it's a valve that releases the brew pressure from the grouphead, allowing you to immediately remove the portafilter after an extraction.

Without this pressure release mechanism, you must wait a few minutes for the water under pressure to leech through the puck. Should you forget to wait, removing the portafilter results in a "portafilter sneeze." The result is hot coffee grounds spattered on the front of the espresso machine and the countertop; there's also a risk of scalding yourself. A three-way solenoid valve is a standard feature on most pump-driven high-end espresso machines.

Randy's pages cited above provide more detail, including a good explanation of why and how to keep the three-way valve clean by backflushing. What is backflushing? and Why is backflushing important? discuss these related topics.

Hi everyone!

i'm restoring old Lelit PL041 as my second coffee-maker and have found that 3-way valve let water leak from the boiler while heating. Also the steam seems to be to weak as for this decent boiler, probably because of insufficient pressure caused by that valve. It looks like here.

When you stop brewing the valve does its usual job spitting water to tray so I guess it is not hopeless.

What do you think, could the series of backflushing restore the valve to normal functioning or I'd better take the valve to pieces and try to fix it?

Thank you! Hopefully I explained all clear enough

trololo wrote:What do you think, could the series of backflushing restore the valve to normal functioning or I'd better take the valve to pieces and try to fix it?

Backflushing is worth trying, but it may be sticking due to scale buildup. If so, the best solution is disassembly and soaking the valve in vinegar. 3-way Valve Removal offers hints on removal/cleaning that can be adapted to your Le'Lit PL041.

Thank you , Dan!