I was concerned that my sightglass wasn't accurately indicating my boiler water level on my Elektra Microcasa semi auto, so i pulled it apart and descaled with citric acid solution. As i refilled the boiler, the sightglass appeared to be reading accurately. When I powered the machine back up and turned on the steam wand, it appeared to work fine except the water level in the sightglass appears to "bob" up and down a good bit (about 1/2 inch at times). It also appears to not be going down at all, though of this I'm less sure.

At this point, having pulled the machine apart and descaled the boiler and sightglass area, I can't figure out what it is. Thanks.

Its all about Vapour Liquid Equilibrium

When the machine is idle the steam and water at boiling point are in perfect equilibrium. Opening the steam valve will release steam and reduce the pressure in the boiler, so the water is all of a sudden above boiling point at that pressure, so it boils, generating steam and increasing the pressure. So the steam 'stored' in your boiler isn't limited to steam in vapour form, but also the heat stored in the water that will boil and turn to steam when you open the valve. And just like a pan or kettle of boiling water, the surface bounces around.

This is also why dropping boiler level won't necessarily give you more steaming power.

Thanks - that's helpful. I'm still concerned about the water level seemingly not going down though - despite consistent steaming. Perhaps there's still some blockage in the boiler - I suppose I could pull it apart again and make sure everything is clean inside.

I've got the same problem with my maximatics, the sight glass is slow to follow the boiler level. Since it is a HX the boiler it is only used for steaming. If it gives you any comfort 1 part of water equals 1700 parts steam so it is going to take a bit to drain a boiler when steaming milk.

Because the sight glass is slow, I have a problem when refilling the boiler and I do the following:

Take a dry wooden chopstick, dip it into the boiler till your fingers touch the fill lip. Take it out, hold it at the same level with the fill lip and compare the wet portion with the indication on the sight glass.

Hello, first post for me here. I have used SemiAutomatica for some years now and it is great machine. Also quite easy to maintain... I did have same issue you describe about a year ago and resolution was to replace the upper and lower rubber grommets/gaskets. They are situated directly above and below the sight glass. Sight glass housing will need to be removed first though (see nuts at either end of housing) and you can see the white rubber grommets resting in place, or they may even fall out upon disassembly. These grommets will, with age, swell as they become softer and restrict air flow on upper boiler tap and/or restrict water flow on lower tap. Hence, you will get "bobbing" in glass as it tries to find equilibrium. Glass may be unable to drain water to/from bottom tap fast enough or possibly also cannot pass air on upper vapour space tap into boiler. This latter scenario would cause vapour lock in sight glass (which would happen upon boiler refill) that would not allow trapped liquids in glass to lower much. This means you have no actual boiler level measurement available. Two new grommets and 1/2 hour of time got my glass working as new again. You may note that old grommets and new grommets feel and look very similar in hand, but under pressure and high temps the old ones will compress and restrict the small openings that feed the sight glass chambers. Hope this helps.

Thanks! I hadn't thought of this before - I'll take a look as to whether this is the problem.