Air/steam coming out of group head after descaling treatment

#1: Post by **veeveenyc** » February 23rd, 2009, 2:21 pm

Hello all, I recently descaled my machine about a week ago. Everything seamed clean and happy. I used Dezcal in the tank and flushed well. I then used Cafiza and backflushed as directed and flushed as well. Everything seemed fine. A few days later after letting my machine warm up for the normal 25 minutes, to my surprise when I activated the brew switch to flush the group prior to pulling my shot, the pump only expelled steam and/or "air" for about 5-8 seconds before any water came out of the shower screen. This machine has been pulling consistent shots and the pressure was dialed back to about 9 bars and I assume the temp is ok because of the quality of the shots. Why all of a sudden is there air in the line? All the hoses are secure and there appears to be static water all along the visible line with no air bubbles. After the initial "steam/air" purge, the machine seams to behave normally. When it sits for a length of time it again builds this "air" pocket. Any thoughts? Did I do something wrong in the descaling process? Thanks, a new E61 convert.

#2: Post by **another_jim** » February 23rd, 2009, 4:07 pm

Has the thermosyphon stalled? That is, is the group cooler than usual, and the length of time the flush boils much shorter? If it has, the return line is blocked, probably from a bit of scale in the jet. If the temperature is back to normal, whatever blocked it has shaken loose, and you are good.

#3: Post by HB » February 23rd, 2009, 7:58 pm

Another possibility is that the brew valve (or 3-way valve if no expansion chamber) isn't seating, leading to the water in the HX slowing boiling away until a steam pocket forms. Look for a slow drip into the driptray from the brewhead pressure release.

#4: Post by **Randy G.** » February 23rd, 2009, 8:31 pm

Nooooo! Descaling... Thermosyphon stall.. I HEAR THE VOICES! The calls are coming from inside the espresso machine! GET OUT NOW! STALL! STALLLLL!!! backflush.. particles!!! Arghhhhhhhhh!!

Is that your gicleur or are you just glad to see me? It's tuned to the key of A... I IV V.. 8 bar blues... Blue Mountain... My portafilter is BOTTOMLESS! The steam.. the steam.. oh, the humanity! EEeee heee heeeee haaaaaa haaaaaaa! NOT THAT LEVER!

#5: Post by HB » February 23rd, 2009, 8:52 pm

Please see Odd Vibiemme Domobar Super thermal behavior for an explanation of Randy's odd behavior. Don't say that I didn't warn you about mocking espresso gremlins.

February 24th, 2009, 12:55 pm

Thanks All,
I spoke with my restorer and he informed me that he had ordered the steam valve gaskets for my machine to replace. Maybe related? The group is if anything hotter than before these symptoms began. Going to open it up this weekend. I will post my discoveries to help others with same problem. Thanks again.

#7: Post by **rivera618** » August 8th, 2009, 10:26 am

I was wondering if you had any updates on this. i'm experiencing an almost identical issue.