# Rancilio Silvia grouphead top screw, and pressure measurement point



## Bastos80 (May 6, 2019)

Hi everyone,

I'm just curious, what is the purpose of the screw on top of the grouphead? Could it be used to monitor temperature, or maybe pressure?

Temperature is already assessed/managed by MeCoffee, I wouldn't go as far as monitoring the delta with groupehead temperature.
On the other hand, I'm considering adding a pressure gauge. I don't want to place the measurement between pump and OPV, as it only measure the OPV setting. I am considering measuring on the steam pipe, I could monitor a manual pre-infusion by the use of steam knob... Or maybe this grouphead screw?

Thanks in advance!


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## dtmr (Oct 21, 2016)

> just curious, what is the purpose of the screw on top of the grouphead?

Purely for manufacturing reasons. They drill a water path into the grouphead (instead of making a complicated casting form) and afterwards have to close an unneeded hole. This picture should explain it.

> Could it be used to monitor temperature, or maybe pressure?

The position is not advantageous.



If one wants to get as close as possible to the real temperature in the filter, that point will not do. For a good measurement, drill straight down through the grouphead and through the shower screen screw. A 0.5mm thermocouple inserted that way (installed with a compression fitting) ends in the coffee. Example: https://www.kaffee-netz.de/threads/installation-eines-temperatursensors-in-silvia-bruehgruppe.111093


For pressure measurements, it does not matter (noticeably) where the pressure sensor is installed at the boiler. It's not necessary to get as close to the filter as possible. It's easier to install the pressure sensor - which is quite long if installed with plug - at another point, e.g. with a 1/8" T fitting at the boiler input port.


If you are interested in installing a pressure sensor, take a look in the appendix "Pressure sensor installation" in the installation pdf of the leva! firmware. leva! adds pressure profiling to machines.


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## Daniel R (Feb 2, 2020)

Hi,

I understand that drilling into the brew chamber is the best option. However, I guess the group head screw is better than top of the boiler? Also, if you are using meCoffee, I would not move the sensor as the offset might be different.

Interesting investigation of boiler and brew water temperature:

https://content.instructables.com/ORIG/F5Q/QN3N/J2UPDZ9S/F5QQN3NJ2UPDZ9S.pdf

Daniel


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## Tonyanagnos (May 11, 2021)

Hi Daniel, I'm thinking of doing the same to my Silvia, installing a pressure gauge and connecting it to the same point, have you done that? What fitting did you use?


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## Daniel R (Feb 2, 2020)

Tonyanagnos said:


> Hi Daniel, I'm thinking of doing the same to my Silvia, installing a pressure gauge and connecting it to the same point, have you done that? What fitting did you use?


 I have not installed anything there. Note that it will not have any pressure or water unless brewing.

My plan is to remove the OPV and install an electronic pressure sensor there. The top screw could be good for a secondary temp sensor the measure the brew water near the puck.


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