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The P/stat used in an Espresso Machine is very sensitive to pressure change and most current models operate within a band of better than 0.3 BAR. If you chase up a Steam Pressure conversion chart, you'll see that this relates to quite a small pressure change, so quite sensitive. Given the mass of the Group Ass'y etc, the actual variation of the Brew Water temperature on to the top of the coffee puck is very small when a machine is setup and tested properly.
There's more to an espresso machine than whether it uses a P/stat or a PID Controller, many more factors effect the result in the cup.
Thank you for that, that makes more sense to me now I think. So the pressure is equivalent to a temperature so the pressure stat acts like a rudimentary PID.
Have attached a Hydraulic Schematic which depicts all significant components in a HX based espresso machine.
Note where the P/Stat is located near the top. With this design, a PID Controller just replaces the P/Stat and doesn't offer any improvement in function or usage. If it offers any advantage at all, it is just related to convenience, in that you can easily adjust the Boiler Temperature without the need to open up the casing and manually adjust the P/Stat. Given how rare the need to do this is, an HX machine marketed as having PID controlled boiler temperature is mostly just a marketing exercise.
Of course, everyone wants to keep up with the Jones' in the marketing departments...
aaarrrnnn > Is it because a PID can't influence a HX's temperatures because of the way it works?
That is my understanding. I believe a HX works by the pump running water through a conductive pipe that goes through the boiler which provides the steam for the milk. That pipe is ultimately connected to the Group head via a solenoid etc. I always flush water through the grouphead before fitting the loaded PF as a crude way of profiling the shot. Don't think a PID would add much to that but the experts here know a lot more about this than I
My understanding is that if you want to make milk coffees you are better off getting a HX unit rather than a single boiler. Also 'midrange' sort of excludes most double boilers. I also understand if you go for a HX machine that there is little point in having a PID on board. Or have I missed something?
I understand this is the case too, but I don't understand why this is the case? I kinda understand that the HX unit has 2 temperature zones, but why wouldn't PIDs help here? Is it because a PID can't influence a HX's temperatures because of the way it works?
I own a lelit Anna, it has been very good to me for the last 2 years. Ide recommend it. It does well with milk, you would struggle if making coffee for more than 5 people, as you have to reprime the boiler after steaming the milk.
My understanding is that if you want to make milk coffees you are better off getting a HX unit rather than a single boiler. Also 'midrange' sort of excludes most double boilers. I also understand if you go for a HX machine that there is little point in having a PID on board. Or have I missed something?
Having a PID is pretty essential. The Lelit PL41TEMD fits well within your budget. If you can stretch / find a deal the PL91T is similar but with a few more nice-to-have features.
I am actually been looking at PL91T - looks to tick a lot of boxes, however I didn't see many local stores carrying them (let alone finding some sort of deal?)
Having a PID is pretty essential. The Lelit PL41TEMD fits well within your budget. If you can stretch / find a deal the PL91T is similar but with a few more nice-to-have features.
Both the Silvia and Lelit are very similar to operate. I like having a PID just to have a bit more confidence in where the temp is at when switching between brewing and steaming.
it’s a fairly quick process with the Lelit to make two milk based drinks as the single boiler still has enough steam for two drinks. I’m sure the Silvia is the same.
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