How a Silvia Works
All wiring
Off
On, heating up
On, at temp
Brewing espresso
Steam, heating up
Steam, at temp
Pumping hot water
Overheated
Modification for PID
Dual Setpoint PID
Advanced Dual Setpoint PID
Coffee Cup
HOME
Complete Wiring Schematic with PID

   In this example I have included all the various wires that would or could be added or modified for a full PID install. The numbers below refer to those in the diagram:

  • 1) The power wires for the PID can be piggy-backed to the existing wiring in the machine. On Silvia this can be done by using piggyback spade adaptors right on the back of the power switch. In this way turning on the espresso machine also powers the PID at the same time. Alternatively, a separate power cord can be attached to the PID and a separate switch wired.
  • 2) The only wires in the machine that are removed or modified are those connected to the original brew thermostat. These are wired to the output side of the Solid State Relay (SSR). Simply removing the wires from the thermostat and using double-male spade connectors works so that the existing wires do not need to be cut. This is done because the entire PID setup is designed to replace the brew thermostat. Be sure that the connectors used are firmly connected and insulated!
       The SSR should be firmly mounted to a metal surface with a some heat transfer paste used. I placed mine under the water tank against the metal base where I found there was a lot of space. Some have mounted theirs behind the face plate, to the right of the 3-way valve. The connections must be protected as the output side carries high current!
        Be aware that the input side of the SSR (the wires that come from the PID and connect to the SSR) are DC, so polarity counts- that is, there is a "+" and a "-" on that side. Polarity does not matter on the other side- the pair of wires that come from the machine.
  • 3) The washer-style thermocouple is attached to the top of the boiler using an existing screw which previously held down the brew thermostat. This is where the PID gets the temperature information it needs to operate. Some heat-transfer grease should be used between the thermocouple and the boiler. Be sure to buy a thermocouple with wires that are long enough for your installation.. The two wires can be equally shortened, but they should not be lengthened.
  • 4) Finally, for safety I ran the ground wire for the PID to the existing ground lug on Silvia's boiler. If you mount the PID in a metal box and the PID does not have a ground connection, connect this ground wire to the mounting box for safety's sake. For PIDs without a ground connection which are mounted in a plastic box this will probably not be used.