Rancilio Silvia Espresso Machine —
Adding a PID

Espresso |  PID'ing Silvia |  part 2 |  Resetting Silvia |  Steam leak
Autofilling Silvia |  part 2 |  part 3 |  part 4

Rancilio Silvia Espresso Machine and Temperature Control

One of my most successful espresso projects was to add a PID controller to my Rancilio Silvia espresso machine. A PID is a Proportional – Integral – Derivative temperature controller designed for industrial use. But, I added it to my home espresso machine to stabilize the temperature of the Silvia's boiler.

This type of modification has been extensively discussed on alt.coffee, which has fueled my desire.  Websites by Pepé and Murph discuss details of the PID modifications. Murph's, in particular, was a guide that I used.

I selected the Fuji PXR3 PID temperature controller from TTI Global for my project.  The goal of this project is to make a dramatic improvement in the consistency of the water temperature for brewing espresso.  The stock thermostat in the Silvia is reported to have a temperature swing of 40 degrees F.  I planned to check mine when I hooked up the thermocouple, before converting the unit to control by the PID process controller.  (of course, I didn't do that...)

The project was a success.  Miss Silvia had a little PXR3 controller named Fuji.  The stability added by the PID has enabled me to make much better espresso.  Of course, the Americanos and other espresso-based drinks were greatly improved, too.

Adding the PID Controller...

Initially, I  mounted the PID in a Radio Shack project box (6x4x2", # 270-1806, $4.99) similar to that depicted on Murph's site, and used the extension cord trick for power.  I mounted the box, opening to the outside so I can work in it if I have to, to the left side of Silvia using double-stick tape, the 1/16" thick type.   I added a 1 amp fuse for the power to the PID.  And, I bought way, way too many male and female quick connectors. I also paid attention to Murph's final suggestions and got the 42" leads on the thermocouple. 

I cut a mounting slot in the Radio Shack plastic project box with a hack saw. I could have put it in a vise and used a scroll saw and been through very quickly. One other thing I did to mine — I put some 1/2 inch holes in the bottom near the front and several 1/4 inch holes in the top near the rear to provide ventilation for the electronics.

The Fuse

From what I've read, not many people are installing fuses to protect the PID — or more accurately, the Silvia and Silvia's owner — from an internal failure in the PID. Fuji's manual suggests putting a fuse in-line, which I did. You can see the fuse casing inside the PID's project box. The fuse case is white and has red wires. I've wrapped both ends of the red wires with black electrical tape, in order to denote that this is the "hot" power wire.

Airflow, or Cooling the PID

From my work with computers, I know that heat is the enemy of electronics. The Fuji PXR3 PID controller's specifications say that the operating environment is designed to be -10°C to +50°C (+14°F to 122°F.

This is the main reason I put the PID in a box on the outside of Silvia, and also located the box to the rear, away from the boiler. I usually keep my Silvia turned on, ready to make espresso or provide hot water, so the controller would be likely to overheat and fail if I mounted it internally. [Contrary to general belief, insulation between the boiler and PID would not prevent the heat from getting to the PID — it would just slow the equalization of temperature.]

Anyway, in addition to mounting the box on the outside and to the rear, I also drilled ventilation holes in it. The vent holes are at the top of the rear and the front of the bottom of the project box. That way, if I manage to spill water on the PID's box, the water won't get inside the box.

Espresso |  PID'ing Silvia |  part 2 |  Resetting Silvia |  Steam leak
Autofilling Silvia |  part 2 |  part 3 |  part 4

Copyright © 2002-2012 Terry A. Stockdale