I'm an electrical engineer, working with the owner of an (old) Rancilio Z-11 Omicron 3-grouphead espresso machine and would appreciate some suggestions on resolving a problem with the steam wands.

Machine is levelled on the countertop. Boiler water level maintained about 1/3 the way down from "max" indication. Boiler pressure slightly greater than 1 bar.

Operating either the left or right steam wand BY ITSELF gives good volume and no water. If right steam wand is opened first, then the left wand is opened, the amount of water in the right steam wand increases as the left wand valve is opened further. But the left wand consistently delivers good quality steam (no water) at all times.

I'm assuming the piping for both steam wands just taps into the top of the boiler, with no dip tubes or anything--RIGHT? Any thoughts?

THANKS!!........Lee

Lee,
Water in the steam can indicate 2 things. 1) Low temperature, 2) boiler too full. When the boiler is at 1 bar the water is held above boiling temperature and is at equilibrium because of the pressure in the boiler. As soon at you open the steam valve the water vapor in the boiler immediately drops in temperature (think a form of PV=nRT from chem 101) and the water begins to boil. When both valves are open the temperature drops even further and the water boils more violently. The lower the temperature of the water vapor the more condensate you will see in the steam.

Sometimes the roiling boil can be violent enough to reach the steam exit (Depending how large your boiler is, how close the water is to the steam outlet, and the contents of the water).

One thing to try is to raise the pressure to 1.5 bar to increase the stored energy in the boiler to see if this helps. It will throw off the temp of the brew water but will be a good troubleshooting step.


BillC

Sometimes the water level indicator is captive and does not change due to scale buildup. If it does not move during multiple shots or when you hear the refill valve open, may indicate this situation.