Channeling woes / Check rotary pump machine's brew pressure?

[sk]

Hi All

I have an Izzo Alex, a plumbed in E61 with rotary pump, that I am suspicious of having a too high brew pressure. Ex. using naked PF and LM triple (or std. dbl.) basket espresso sprays all over the place, machine, table, floor & me - through out the extraction. Also when running the cooling flushes I have to, more or less, cover the group head with a cloth to avoid scalding. I remember that part less brutal on the Izzo Vivi I had before (E61 vibratory pump) which was adjusted to the same boiler pressure 1.1 - 1.3 bars. Shots are of the expected size 30 & 60 ml, but more often than not too bitter / harsh / unpleasant. I have a feeling that my grind is finer than before, however the grinder is also new, a Mini E.

Is there anyway of estimating the brew pressure with out a PF with gauge, that I have no intention of investing in. Or is brew pressure not the problem at all?

Best regards,


SK

[HB]

Espresso sprays everywhere like this?


System Meltdown (click image to see more)

Higher pressure can increase the likelihood of spectacularly bad channeling like this, but flawed dose / distribution / tamp / grind setting / old beans are also big factors. Your machine looks a lot like the Bricoletta that Chris recently reviewed. If there is no brew pressure gauge, a portafilter pressure gauge is the only way to accurately regulate the pump. A boiler pressure setting of 1.3 bar is on the high side; depending on the machine characteristics, desired temperature, and your usage, you may find 0.9 bar easier to deal with. The steaming will fall off but the flushes will be a lot smaller and less forceful. That said, 1.1 bar at the top of the boiler cycle is a good starting point for many HX machines.

[sk]

Yep, it sprays like that. channeling is a fact now and then but definitely not always! - I do try run the Schomer preparation technique.

Boiler pressure cycle down to max 1.1 - believe I've been there. But as I think it never hurts to try over again I have reduced the boiler pressure cycle to 1.0 - 1.1 ± errors of parallaxes. The first 3 shots came out watery and maybe a bit sour, more or less as expected.

SK

[HB]

Watery and sour = severe underextraction. The pictured "system meltdown" was an intentionally horrendous pour. If you're seeing it now and then, then deal with it now. Properly regulating the pressure is step #1. Further diagnosis is not meaningful without knowing if your pump is putting out 8 bar or 18 bar.

PS: Installing a temporary (or permanent) brew pressure gauge isn't difficult if you're handy. Below is the temporary setup I did for the Cimbali Junior writeup; it's simply a tee added to the pump's output line, pressure gauge, and snubber (to reduce needle flutter):


All John Guest / Watts push-in type fittings for easy removal