TY,

Are you up to studying temperature? I have found that a very thin wire thermocouple can be inserted into the boiler under the group to boiler gasket. This would need to be done anyway if you plan to add a PID to the machine. To preserve the gasket I made an additional gasket of softer rubber, in my case, silicone. The seal holds.

You could then drill a filter basket and insert a thermocouple there to measure water temperature exiting from the shower screen during a pull.

You can also use an available through wall, port on the top of the boiler, if an extra one is there, to thread a thermocouple probe into either the steam area, or water portion. I have found proper fittings, as well as using adapters for the thermocouples.

Porter, could you show us these fittings and adapters?

drgary wrote:You could then drill a filter basket and insert a thermocouple there to measure water temperature exiting from the shower screen during a pull.

Hi Gary,
I already took such measurements, see below. Very entertaining...
In the future I might consider PIDing the prestina. I have a TC sensor with a male 1/4 thread and a Auber PID lying around...
The probes can be purchased at the website below (approx 20 eur). They carry a male 1/4 thread so easy to drill the boilerplate...
Cheers, TY

https://www.sensorshop24.de/temperaturf ... d/a-97001/

Got it. Reading what you've already written, then, how are the shots on your Prestina if you turn up the temperature?

I am very appreciative of this thread. Initially I was thinking I should replace my spring on my Prestina, but now I'm thinking a PID makes much more sense since the spring pressure seems to affect extraction significantly less than temperature.

Gary did you figure out a thermocouple to attach to the heating element as a failsafe for heating without water? I'm thinking if I'm adding a temp sensor between the group/boiler gasket for the PID, adding one to attach to the heating element might be appropriate at the same time I have the boiler apart.

I have a pressurestat set at the upper limit. Not completely fail safe but would slow down overheating. I suppose it could be done without an extra thermocouple by setting an alarm in the PID.

drgary wrote:Porter, could you show us these fittings and adapters?

I use 3/8", as seen used for the over pressure safety valves. I believe that this product (below) is close to what I am using. I like that it is stainless and robust, as it could last to be used on yet another project. No leaks, no flaws, very stable readings. There are plenty of options there to adjust your desired outcome.

https://www.omega.com/en-us/sensors-and ... blEALw_wcB

LS.,
I've been giving this PID mod some thought. The probes have a 1/4 male thread, so I would have to drill a hole in the brass frontplate (no problem).
Question remains, where to position the probe?
1) Not to close to the (cold)water inlet;
2) Low, since the probe has to submerged;

I have identified three potential positions, A, B and C. I see position C as the most suitable. Appreciate your thoughts.
Cheers, TY

erics advised me awhile back that the probe should be mounted above the water level, in the steam. By then I had already mounted a thin wire Teflon probe by threading it through the brew group to boiler gasket and fastening the end to the dipper tube with an o-ring, leaving the tip extended a couple of inches past the end of the dipper tube and bent upward. It's probably in the boiler water, and it works fine. Since the wire of the probe creased the group gasket, when I reinstalled I cut an additional gasket from soft silicone, where the wire embeds and it seals without a leak.