Rancilio Silvia with pre-infusion PID

Double shot from Rancilio Silvia fitted with the Auber pre-infusion PID

Category:

Science & Technology

Tags:

• espresso
• pid
• silvia
• pre-infusion
• rocky coffee

[dakosMD]

I see that on 2:06 of the video the temperature drops down to 72 degrees, it means the end of the shot doesn't taste nearly as good as it should, how is that possible?

[robives]

@dakosMD The temperature on the display is measured at the top of the boiler where the cold water enters. The temperature at the group head only drops a small amount. The coffee tastes great :-)

[dakosMD]

@robives I may be wrongfully assuming that all PID installs have their sensors on the same position near the cold water inlet on the boiler, since it gives the best response to temperature changes in the boiler. But as seen in this video of a different PID:

"Rancilio Silvia with PID" by charliem169

The temperature only drops to 98.2 degrees, much more stable and will have shorter recovery times then the Auber PID, can you please explain the difference between the two PID's regarding that issue?

[robives]

@dakosMD The recovery time is mainly a factor of the amount of energy that can be added to the water via the heater element and the thermal capacity of the water/boiler combi. The programming of the PID will only make a limited difference. The two machines have a common boiler mass and heater I'm guessing that the apparent difference in temperature drop is more an artefact of sensor placement rather than an actual difference in brew temperature.

[dakosMD]

@robives That's no a 100%, in addition to wattage and boiler thermal capacity, there is one more thing that effect's both recovery and brew temperature drop is the time the PID put's the boiler to work. You can see initially, during the start of the brew, the light indicating when the boiler is ON is flashing on the Auber install while on the other PID it's constantly lit meaning it's working at it's best to recover and at the end of the brew it's virtually recovered

[robives]

@dakosMD I'd be surprised if the PID profile varies much from machine to machine. PID control is based on a fairly standard algorithm (proportional–integral–derivat­ive) which should give the same output for the same conditions. I really think that the variations in heater output are most likely an artefact of sensor position.

[robives]

@hitechespresso It is possible to pre-infuse if you use the pre-infusion PID fitted here

[jazzijoy42]

Can you tell me what you pressed on the PID to make it stop the extraction? I usually have to eyeball it and didn't realize there is a setting on the PID that does this for me.

hanks

[robives]

@hitechespresso Pressure will ramp up whatever type of pump is used. It is a characteristic of a sealed system.

This has nothing to do with the temp control. The PID keeps the temperature more stable that the usual thermostat keeping it closer to optimum brew temperature.

[robives]

@hitechespresso Pressure will ramp up whatever type of pump is used. It is a characteristic a sealed system.

This has nothing to do with the temp control. The PID keeps the temperature more stable that the usual thermostat keeping it closer to optimum brew temperature.

[hitechespresso]

Al ittle known fact is the characteristic of the Ulka pump used in the Silvia and hundreds of other machines. the pressure profile RAMPS up over a period of 4 to 5 seconds to 9 bars (with coffee in the holder). ALL ULKA vibe pumps do this, it is normal and expected. Gimmickry using the temp controller does nothing.