Brew pressure too high and unstable

#1: Post by **swilson59** » May 12th, 2010, 1:29 pm

The Astoria, sae 1/jun, i recently bought used, 4 yr old, seems to have a brewing pressure issue. When i started using the machine it was espressing at 10 bar. So i bought a new gage, still 10 bar, whether auto-filling or espressing, about 3bar idle, and boiler pressure at one bar. Then the next day it was espressing/ auto-filling at 12 bar and promptly blew up the auto-fill solenoid. I adjusted the internal pump regulator, backed out 1 turn, replaced the solenoid. The next time i brewed it was espressing/filling at 8 bar in the morning. By the afternoon it was up to 10 bar. What's up, why isn't the pressure stable????

#2: Post by HB » May 12th, 2010, 1:33 pm

Is it a plumbed in rotary pump? Maybe it's the inlet pressure that is not stable. See Water pressure and the effect(s) it may have on rotary pump for details.

erics wrote:The pressure measured at the inlet to the espresso machine affects the pressure developed by the pump. The pressure developed by the pump is brew pressure, typically anywhere from 8.0 bar to 9.0 bar with 9.0 bar being a "favorite". One bar is about 14.5 psi (14.5038 psi) and the inlet pressure will affect the outlet pressure on a one for one basis. This pressure and any variance it may have has no influence on the pressurestat setting or vice versa.

Normal water pressure in a home is, say, 60 psi. However this can vary between 45 and 75 psi depending upon what other fixtures are in use AND whether or not your neighbors decided to hold a car wash fund raiser. This is why a pressure regulator set to maintain, say, 35 psi (or whatever the espresso machine mfg recommends) is a necessity.

May 12th, 2010, 2:05 pm

You got it, it's inlet pressure. Water pressure here at the shop can be from 4-6 bar.