Technical question

dfk41

Can anyone help? I have recently taken delivery of a Sage Dual Boiler and in the week of re-learning this machine I have been very happy. My routine as always is to switch the machine on whilst getting ready. The theory is that to comply with EU regulations, it has to switch off after 20 minutes. I presume therefore it is fair to assume that the machine reaches a working temperature in that time. The brew boiler reaches 93 in 4 minutes. So today, when the machine switched off at the 20 minute mark I turned it back on immediately to make my brew. I touched the collar on the group and it was lukewarm. I took the pf out and it was as hot as you would expect. I ran water through for 20 seconds, no improvement. I rang Sage and spoke with a very helpful but seemingly useless young lady who sent me the following email:

To address your concern and clarify that the machine is not designed for the group head to become extremely hot to the touch.
The group head you checked earlier is made of stainless steel and does not contain a heating sync/ element inside it. Instead, it is warmed indirectly by the hot water flowing through the brewing system. Because of this design, the group head may feel warm rather than very hot, which is normal and does not indicate a fault with the machine.
Rest assured, as long as the machine is reaching the correct brewing temperature and producing hot water properly, it is operating as intended.

Now, that goes against all my instincts. Everything I can see online suggests the group is brass and should reach an 88 - 95 temperature. I just wondered if those who knew more than I think that the group can perform whilst not being too hot to touch and why the pf is too hot.

Under Distance Selling I can return the machine which I do not want to do but nor do I want a faulty one!

dfk41

Using ChatGPT I re-phrased my question and it chucked this up:
Here’s how it works:

The group head is actively heated by its own dedicated heating element (cartridge heater) embedded within the group assembly.
This heater is controlled by the machine’s PID temperature control, helping keep the group close to the brew temperature.
The group is not heated primarily by a thermosyphon loop from the brew boiler, as on an E61 machine. Instead, the cartridge heater provides direct heating.

This design has several advantages:

Faster warm-up than a passive E61 group.
Better temperature stability between shots.
Less temperature loss when locking in a cool portafilter.

In practice:

The stainless steel face of the group will become quite warm, but it won’t usually be painfully hot like a commercial E61 group running at around 90–95°C internally. The exposed metal often stabilises somewhere around 50–65°C, depending on ambient conditions and how long the machine has been on.
After 20–30 minutes of warm-up, the portafilter should also be hot to the touch if left locked into the group.

I guess this ties in with my experience, which I am relieved about…..even though I find it hard to follow as it means you do not really know when the group is up to temperature

dfk41

I have been thinking overnight, and I am still struggling slightly with how the pf can be too hot to touch (expected) yet the collar of the group is not.

I am hoping that one of the forums distinguished and most learned members can assist this old donkey!

Clodius

I asked Gemini for you. It gave me a long explanation and a diagram.

Here is the simple explanation for why the portafilter gets hot while the outer collar stays cool:

The Portafilter is Hot: Inside the machine, there is a heater clamped directly against the metal where the portafilter locks in. Metal touching metal transfers heat instantly, making the portafilter burning hot.

The Outer Collar is Cool: The silver ring on the outside of the machine is just a plastic/decorative cover. It is separated from the hot internal heater by air gaps and rubber seals so you don’t burn your hands on the outside of the machine.

In short: The part that touches your coffee gets hot; the decorative outside shell stays cool.

Sage customer service gave you wrong information about how the machine works, but the machine itself is performing completely normally.

dfk41

Clodius I asked ChatGPT and the answer was not as detailed as your matey. I guess that I just have to shrug my shoulders and accept this new way of doing things. I suppose the answer is once the boiler heats up, give it a few minutes then disengage the pf and check that!

As always, many thanks