Hoping someone can give me a rundown of the following regarding the gauges.

- What exactly they're reading. I know boiler and brew pressure, but what exactly does that tell you?
- Ideal readings
- What all impacts these values? That is, if you're not getting one of the ideal values, what can be tweaked.

Thanks!

Is a somewhat broad question, but since no one has responded I'll weigh in with some very basic answers.

JDW_ATX wrote:I know boiler and brew pressure, but what exactly does that tell you?

The boiler pressure on your machine is directly related to your PID setting. It tells you the temperature/pressure in your boiler, which affects the temperature in the HX. Too high = too hot, with the result that you'd will need to do more flushing to get the HX down to temp. Too low and it will take longer for the machine to rebound after a shot. Also, if too low you will have less pressure for steaming. If it goes unusually low or high without changing the PID setting that might indicate a problem in the system such as a bad temp sensor, bad anti-vacuum valve, bad or clogged gauge, etc.

The brew pressure tells you little that you don't know from watching or timing the shot. If too low, that probably means you need more resistance in the puck - you need a larger dose or finer grind - and that will be more obvious from watching the shot than from looking at the gauge. Ideally it's never that high, so that even with a blind basket it won't ever go much over 12 bar. If it goes way high that might be an indication of stuck closed expansion valves (I believe your machine has two.) If it never gets up to pressure even with a backflush blank then you may have a problem such as a stuck open expansion or priming valve, or a bad pump. When flushing the machine with no PF, you will see a little pressure on the gauge, maybe around 3 bar. If you see this flush pressure go unusually high then you have a good indication that your gicleur (jet where the water enters the brew chamber of the group) is clogged.

JDW_ATX wrote:- Ideal readings

The boiler pressure depends on your PID, setting with ideal in the neighborhood of 0.9 to 1.2 bar. The ideal is pretty loose, and depends on what you want for steaming and how you do your flushing and waiting. See the HX love How-To for some basics on flushing if you're not yet familiar with that.

The brew pressure should eventually ramp up to around 9 bar when brewing. When doing a backflush with a blank filter, it's OK to go up to around 12 bar. Some people would argue that if you like to pull ristrettos it's best if the brew pressure never gets above 10 bar even with a backflush blank.

JDW_ATX wrote: if you're not getting one of the ideal values, what can be tweaked.

For the boiler, on yours it's a simple matter of changing the PID setting.

Lowering the brew pressure on yours would involve adjusting an expansion valve (also called an OPV valve), and can be a little confusing on the newer Giotto/Cellini machines. See OPV on Rocket Cellini V2 is confusing.