Replies to This Discussion

Permalink Reply by Mike Sabol on May 13, 2010 at 9:17am

That guage wanders when the heating element kicks in. Since LaMa's have the dual boiler and an active heating element rather than the heat exchangers the guage moves based on the expansion of the water when the element fires. It will climb to 14-15 bar and then suddenly drop to around 13, which is what most of the expansion valves are set for. It will then stay there mostly until the element turns off or you pull a shot. Once the element is off you'll see the needle fall back down the the line pressure number, usually between 3 and 5.

The reason you don't see this on other machines is that when the water is being heated in the hX and expanding, which also makes it lighter so it rises, it moves up through the thermosyphon tubes into the group head to heat up the metal, and therefore cool itself down and then falls through the lower thermosyphon tube. The expanding, contracting, and the convection current of the thermosyphon makes the internal pressure more consistant on hX machines. They still have a expansion valve that drains into the drain cup but you don't see the same kinds of temp swings. I also think it has to do with the fact that in a hX machine the water is always being passively heated while in the LaMa the water is sometimes being actively heated. So in the LaMa you would get a much more pronounced expansion of the water when the element is on and therefore bigger swings on the pressure guage.

• ▶ Reply

Permalink Reply by Kevin Ayers on May 13, 2010 at 10:59am

Yep, wandering gauge is normal.


Mike, shouldn't that be more like 12 bar? I thought the marzocco manuals I've read say to set it to drip at 12. I could be wrong though. Probably a moot point anyway.

• ▶ Reply

Permalink Reply by Mike Sabol on May 13, 2010 at 12:26pm

I don't know if the manuals recomend 12. For some reason I've always used 13. I think I was originally trained that way but I've never bothered to verify that number with LaMa.

What is important in saying this is that I've noticed that the guage will shoot past the set point by about 2 bar and then drop down to the set point. So the needle will go up to 15 and then drop back to 13. Or 14 and 12.

• ▶ Reply

Permalink Reply by ryan mcdougall on May 17, 2010 at 7:31pm

yes, relief valve set to 12 bars, pump to 9.

Kevin Ayers said:

Yep, wandering gauge is normal.


Mike, shouldn't that be more like 12 bar? I thought the marzocco manuals I've read say to set it to drip at 12. I could be wrong though. Probably a moot point anyway.

• ▶ Reply

▶ Reply to Discussion