My eighty-something Faema Compact S, like many other machines, doesn't tell me anything about brewing pressure. Instead of making a gauge attachment for a portafilter, I thought I'd try to install one permanently in the machine.
The problem is figuring out where to place it. I've looked at a few different options, but I would really appreciate any input, as this is not my area of expertise.
The first option is on top of the group head. There is a large threaded plug on top of the head, revealing a hole about 1/2" or so across. When I start the brewing process, there is water coming up in the hole, but I'm having some problems figuring out if it is forced out by the pump or stems just from the line pressure. There is no water in the hole unless the brewing solenoid is triggered.



The second option is a blanked out fitting on the filler valve in the bottom of the machine. From what I've found, there might actually be a Compact model that connects a pressure gauge to this point on the filler valve.
There definitely is water coming through this fitting, but it doesn't look like turning on the pump adds any pressure. I tried attaching a hose directly to the fitting, and there is no obvious change to the water pressure with or without the pump. Obviously, I can't know for sure without a pressure gauge, which is my goal for this project.



Here's a thread with a parts list that shows the fitting being used for a pressure gauge: Faema Compact S rebuilding. Asking for help and advice.

The third option is of course tapping into the pipe feeding the group head and soldering in a T coupling, feeding a pipe to a gauge. Using one of the threaded options would be much easier, if applicable.