Adjustable boiler pressure should be standard equipment. Optimal espresso pressure and optimal steaming pressure are not the same.

Wolfhound wrote:Adjustable boiler pressure should be standard equipment. Optimal espresso pressure and optimal steaming pressure are not the same. image

Cool mod, but it seems to me that your assumptions are not totally on the mark. Steaming pressure comes from the p-stat (or a PID). But the brewing pressure comes from the manually operated lever, not from the boiler, apart from some modest preinfusion. Since the boiler in a dipper machine is used for steam and brewing water, it might be useful to control the pressure as it relates to temperature. However, on most dippers, there is a huge amount of thermal mass that would preclude changing the temperature at the group head with any rapidity.

True, but it's a La Pavoni, not most dippers. The original design used two boiler heating elements to control steaming pressure separate from pulling temperature. In pressurestat versions, modifying to run two pressurestats so the boiler can easily switch between different temperatures for steam vs. pull is not uncommon (although I would convert to a PID.)

Regardless, most espresso machine pressurestats are not designed for daily pressure adjustments, so I'd be worried about that for the OP.

The higher pressure necessary for optimal steaming forces the water to be too hot for optimal espresso. The pressurestat appears to be an on/off switch for the heating element that is triggered by the expansion and contraction of the water/air mixture, thus the pressure, in the boiler. It operates very similar to a thermostat. I suppose I could just use the on/off switch myself, but with the pressurestat, I don't have to stand there and monitor it. Also, I pull the shots that I need at 0.5 bar before I steam at 1.25 bar, so it's a one way progression, not back and forth. So far it's working great.

I'm not a safety design engineer, but I would use a plastic knob instead of a big metal bolt accessible from the outside. It would look nicer and not conduct electricity.

This was initially for proof of concept. I do like the way it works and I do plan on making it more attractive and easier to use. If and when I get a Strietman CT2, this will turn into a $700 milk steamer.