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Personal opinion:--
the benifits of PID control of the steam is very marginal, particularly once a PID is in use for Brew temp and a display of boiler temp is available.
The display tells you when steam is ready ( 120+ C ) and the standard steam thermostat will keep the temp between 120 and 150C, such that i have never had any issue steaming up to 300 ml of milk. If you plan on steaming more than 300ml, then you are asking a lot of Silvia and a PID may help a little.
For me, the added complication and effort for dual control from the PID would not give any benefit.
JMHO.
Originally posted by 53545F484E535B023A0 link=1339685882/10#10 date=1339967769
However, not sure if you can trigger a 2nd set point by external control or not
You dont "trigger" the second setpoint, its always active, there are two outputs on the controller, you wire them to two separate SSRs (or one, dual SSR), the trick is you only feed power for the boiler element through the steam SSR when the steam switch is closed, if you cant figure out how to do that from the schematic in your Silvia manual you should consult somebody qualified/experienced.
That said, dual setpoint isnt necessary for steam control, its possible to do steam control with a single setpoint PID controller so long as it has an alarm output, there are various options for how to achieve this, the Skene design is probably the most common but I dont particularly like it myself (I modified my PID controller to turn the relay contact alarm output into a pseudo-SSR output and then I treat it like a dual setpoint (Yes, Im a qualified Electronic/Electrical Engineer)) the main benefit is you can do it with a single SSR, but given the price of SSRs vs the need for an additional power supply (and some more complex wiring) its neither here nor there.
On sizes, ideally you want a 1/32 DIN sized unit, thats the "normal" size people use (~22x44mm face) though if youre mounting it externally you can get away with a larger unit, the most readily available size when I was looking was 1/16 DIN (~44x44mm).
I tried using the Sestos PID on a little Saeco, results were not the best, probably because of the temp swings of the tiny boiler fooling the PID.. not amount of setting changes seemed to work, I got it good enough but not perfect.
The Autonics TK4S-14CN looks like a reasonable upgrade from the Sestos with the added advantage of having multiple set points (steam controlled by pid). However, not sure if you can trigger a 2nd set point by external control or not.
Depending on what "functionality" you want from it ..( Brew temp , steam temp, pre-infusion, brew time , etc etc) will help identify which PID to get.
Suggest you google "Silvia PID " .. or similar an read some of the many conversions that have been done to get a better idea.
If you just want brew temp, almost any of the cheap ones will work.
Also ,.. be aware of the different sizes & shapes !
4. ~$65 -70. $42 for PID, SSR & Thermocouple then connectors, wire and project box. Way to much fun!! Every time I pull a shot I secretly smile and say I did that.
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