I'm about make a modification to my Livia 90 so I can constantly monitor the water temp just as it goes into the brew head by installing a Tee connector in the line between the three way valve and the brew head. I'm permanently installing a thermocouple about two inches from the brew head and a small digital display to do this. I'm getting constant changes the cut off points of the boiler pressure gauge during the day by as much as .3 bar, which may the TStat acting up, so I want to see if that change is affecting my HX water temp during the brew cycle and it's a pain to check with the bead probe in the basket and that's only good for those couple of checks, not much help for daily use.

While making this change, I was thinking about adding a port to monitor the brew pressure, but is that something worth the additional expense and trouble. Adjusting the brew pressure is not something readily done, you have to take the cover off the machine and change shims in the OPV. By using a gauge in the bottomless portafilter I have it set for 9.1 bar and it's easy enough to check like that. I also installed a Tee connector in the OPV pump input so I can connect a gauge and monitor pump pressure anytime I want. I just don't have room in the machine to permanently mount a gauge.

I was thinking is it was beneficial, I would buy one of those dual gauges that's monitors both boiler and brew pressure but most of those in the size I need are somewhat expensive and the range of needle movement is so small, it looks as though it would be hard to tell much change in pressure, unless it was a drastic change.

As I recall, data shows that flow goes up with increasing pressure and then starts going back down as you exceed something around 9 bars and the coffee gets compressed.

I recommend that you get the ability to control flow and pressure (say with a variac) before you bother with measuring them.

Thanks, pretty much told me what I figured. I seriously doubt I will ever get deep enough into espresso to start wanting to tune my flow/pressure for a certain shot. I know I would never be trying something like that on this little machine.

Well, typical situation, I just got through installing my thermal probe and connecting a digital display and I guess the display is bad (it's been sitting siting in a box junk like that for several years) or the probes are not designed for these low temps (they are some of my EGT probes I use in my engines), I will have check with the company I get this stuff from and see. I've tried five probes and none of them will give me a reasonable reading. When it's too hot to touch, I know it's more than 90 - 120 degrees. At least I was smart enough to order me a new line and used it to build the manifold I was connecting into instead of cutting the one on the machine. Back to the drawing board.