> A lever machine with heat exchanger is miles beyond what leva! is designed for. It's for machines with water straight from the PID-controlled boiler and preferably not with E61 group (examples: Rancilio Silvia, Bezzera BZ09, ...).
(well, it's some kind of an irony: one of the meaning of 'leva' in Italian is 'levers'
I did understand that from the beginning, but it is about the first phase of the shot, I mean the preinfusion
the preinfusion starts once the lever is brought down: the pump is started by a microswitch, the water is filling the 'brewing' chamber into the cylinder and above the puck; the whole volume is up to 75-80 ml;
at about 50 ml pumped into the chamber the pressure starts to build up to a maximum of, say 10 bar;
the puck is saturated, there is already a flow beneath the portafilter;
I am now monitoring mainly only this part of the shot and is this part I wish to control with an ito/leva! proper configuration;
of course, after the preinfusion, begins the manual part of the procedure, that is, the lever is raised by hand, the microswitch disconnects the pump, and the piston descends pusshed by the springs;
sorry for returning to the same description: I have a manometer mounted on the pump exit, after the opv and the check valve, an ordinary dimmer, switchable, to supply the voltage to the pump and a regular pid/SSD to control the 100W heater of the group (same as for Bezzera BZ09/07 etc.);
thermocuple K sensors on the lower/front of the cylinder and on the pipe exiting the HX;
all temperatures profiles recorded via USB datalogger (an Arduino Uno and MAX6675's - in replace of a much better myPCLab, unfortunately damaged!)
what I would hope to accomplish by using a ito/leva configuration:
a pressure sensor at the pump exit (?), a flow sensor at the pump input, temperature sensors for the 2 PIDs controlling the heating into the group and in boiler (for this I have an external SSR); I wonder if there are some recomendations for the places where to glue the sensors;
there must be a way to setup easily the pump flow (the rotary encoder?);
also, I would use the leva! for programatically run a certain pressure profile during preinfusion: i.e. 2-3 ml/sec until the pressure exceeds 0,7 bar, then a slow ramp (depending on the programmed flow, but it could be anything between 6 to 20 secs) up to 10 bar (to make a smooth transfer onto the springs)
is all these feasable? do I need an OLED display kit, or everything could be solved OTA? can I have all the profiles recorded (pressure, flow rate, PID temperatures...)
> using a chart wouldn't work ...
I meant, if you have determined a pressure-flow characteristic of a solenoid pump under different flow/pressure settings, for your solution for controlling the pump;
or, putting in another way: if the pressure ramp of the pump is programmed (or button set?) to be a very slow one, will the pump manage to rise the pressure in the cyl chamber up to a maximum allowed (by OPV), of 10 bar?
in my setup, the pump is controlled by missing erraticaly some strokes, so with lower flowrate, say 2.5-3 ml/sec, I get a very long 'soaking', 0 bar phase (15-20 secs) then the pressure builds up, again slower, until the pump 'dies' around 2 bar... so its characteristic pressure-flowrate is moved to the left: