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Controlling Silvia steam with PID

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  • Controlling Silvia steam with PID

    As some of you know, I have recently been investigating the feasibility of controlling both brew temperature AND steam temperature on a PIDd Silvia. I know many others have done this, and it may be old hat, but I was unable to find a simple recipe for the project that also accomplished my objectives.

    I needed the steam mod (just like a standard PID mod for brew temperature) to be totally transparent to the user. This ruled out the simple method of temporarily changing the SP on the controller. It also meant that the switch lamp on the steam switch needed to illuminate when the switch was flipped.

    Randy G now has a wiring schematic on his pages (clink the link for How a Silvia Works) for exactly the mod described above. After working with him on a couple of minor revisions, that scheme is what I decided to use.

    Today I finally installed this mod on a Silvia for the first time. Although the wiring changes are not that complicated, it is a very tedious job. Access to the steam switch requires a pretty extensive disassembly of Silvia - and even then my short, stubby fingers were nearly useless in the tight quarters.

    Fortunately, I can report that the wiring schematic on Randys site works quite well. When you turn on the steam switch, the switch lamp illuminates, mains voltage is supplied to a mechanical relay, which in turn closes a set of contacts. The contact closure generates a "lo" event at the controller (Watlow in my case), which causes it to select its "event set point."

    Completely transparent to the user. The only visual indication that something has happened is the immediate change in SP from the normal SP to the event SP (on this US machine, from 228F to 300F). The PID instantly energizes the heater, and then brings it to farily quickly to SP. In short, it works.

    This mod was done for a customer (who has been patiently waiting for several weeks) - and I will be shipping it out Monday. That is not going to give me much time to evaluate how much of an improvement the PID control makes in steaming performance. About all I am going to have time to do is make sure everything works reliably before I send it along.

    Once you have a controller with an event input, the additional cost to add the steam control is only around $8US for the mechanical relay. I used an IDEC model (RHB series) because it was sized perfectly and because it has tabs sized to fit push-on connectors. The job also requires 2 additional control wires to be run out of the back of Silvia into the external PID enclosure, 2 short high voltage leads from the steam switch to the relay coil, a short jumper across the old steam tstat, and capping a wire that has to be removed from the steam switch and abandoned in place.

    If anyone is interested in more details, check Randy Gs site, or reply here on CS.

    -- JGG

  • #2
    Re: Controlling Silvia steam with PID

    Hi JGG,

    I have recently purchased a Silvia and have fitted a PID using directions found on the web. It is a dual setpoint controller and I have also bought a relay to control the steam temperature. Unfortunately I do not fully understand the wiring diagram on Randys website and after a couple of attempts at following it either have the relay always powered when the thermostat is on or the steam switch light contstantly illuminated! Could you please tell me which wires have to go where from the back of the steam switch to the relay and which one is disconnected? Also I do not have a green wire coming from the back of the switch but a grey one ( I assume it is the same one).
    Thanks in advance,



    • #3
      Re: Controlling Silvia steam with PID

      Hi All,
      Thanks to the help of a multimeter and reading the directions again I have got the steam switch wired up to energise the relay when it is turned on. For those of you that were wondering - I had to disconnect the grey lead from the steam switch and blank it off, running a lead from the now vacant terminal to the relay...
      Unfortunately I now have a new problem. I have a Cal Controls PID which has the option of a second setpoint. What I cannot work out are the menu settings required to trigger a new output temperature on this controller. I have played around with it but all I seem to be able to do is make it work like an alarm. Now I am wondering if this controller can be configured to control the steam at all? The output device for setpoint 2 is a relay - is this correct? I am starting to get very confused! :-/
      Here is a link to the manual : - if it asks you to register just click on "having problems registering" and it will take you straight to the downloads page!
      Any advice would be greatly appreciated! Great site too! The more I read the more I need!


      • #4
        Re: Controlling Silvia steam with PID

        Hi, CaptainDan -

        Sorry to be so slow in responding - vacation, you know.

        Wiring changes for steam control (sounds like you have already got this part working):
        - new lead from relay coil to the currently empty spot on the steam switch (high voltage - hot side)
        - replace gray lead (disconnect, cap) with a second new lead to the relay coil (high voltage - neutral side)
        - short jumper across the existing steam tstat
        - two new leads from relay (the DC switched side) to the PID

        Cant help with the PID programming since I am unfamiliar with that controller. I have personally only used the Watlow 96 for this purpose but I also believe that the Omron E5CJ-Q2HB controller will work.

        -- JGG


        • #5
          Re: Controlling Silvia steam with PID

          Hey JGG,
          Thanks for the response! Got the wiring sorted out but have discovered that the PID does not have an event input! Wiring has gone back to stock standard and the PID is working fine controlling the brew temperature. Hopefully this will help someone out in the future...