erics wrote:That can, potentially, do more harm than good. The brewing hydraulics become a closed system once the lever is lowered to the "off" position and the thermosyphon system is enabled. Lifting the brew lever, for the purposes of taking a gage reading down, upsets the thermosyphon system.

Nate42 wrote:Your machine has a rotary pump, which can generate enough pressure at any reasonable flow rate that you should expect it to always read 9bar, or whatever its set for. A vibe pump will show more variation since they can only generate full pressure at low flow rates. Other than confirmation that your pressure is set where you want it, it really doesn't provide you with any information you need during a shot. If you want confirmation that it works, with your machine off and cold it should read near zero. You will use it if you ever decide to readjust your pressure, and you might give it an occasional glance to make sure nothing has changed (if it starts behaving strangely it can be a sign things have gone wrong) but other than that you can pretty much ignore it.