donn wrote:I haven't yet been able to completely follow all of this, and I'm not the expert around here either, but to the best of my knowledge ... a pressurestat (e.g., Sirai) and a solenoid valve are two different things.
The sure are. But they are (in my machine anyway) both made by Sirai. Good to know that you too consider the pressurestat sound being lower than the one from the solenoid valve.
So the pressurestat, to my knowledge, react on pressure changes only.
The solenoid valve is only activated when the water lever sensor is over waterline (again, to my knowledge..).
My thoughts on action taking place in a Pavoni 1EL:
The coffee making starts when the lever is lowered and water is flowing from the boiler into the chamber in the grouphead. This will cause a pressure drop (am I right?) that might engage the pressurestat. It will also cause a drop in water level, that might engage the solenoid valve. Just might...
For a one group lever machine, my boiler is huge. The pressure tank is 6,5 liter (with a content of 3,8l steaming hot water).
So I'm not so sure that the change in temperature, caused by the incoming 0,6 liter of water from the reservoir, will make a big enough pressure drop to engage the pressurestat. Nor do I know if the drop of pressure caused by letting out 0,6 liter to the grouphead chamber will effect the pressurestat.
I'm not even sure a combination of those two events will engage the pressurestat, because we might have an other factor to consider: Added pressure from the pump, filling the boiler (the must be a change (rise) in pressure, otherwise the water will not be able enter to the boiler.
So the fact that the boiler is hugh and has a big water content, and we have a lot of actions taking place (simultaneously), I guess it's impossible to separate/isolate what impact the different events will cause.