Low Temperature on New HX Espresso Machine - Page 2

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Postby Bluenoser » Jan 12, 2019, 4:35 pm

Radio.YYZ wrote:
One thing i am finding, and i will have to confirm is that if the bump is higher the shot does change the flavour so thats why i do a flush to reduce the hump. My hump is around 203.5-204.5F after a 4-5second flush. I wait five minutes or more for my second and follow up shots and i get consistent results (only a quick 1-2 seconds screen flush)..

It's very hard to know how much of a 'bump' the puck actually sees. The bump in the TS water that the thermometer is measuring is very much 'filtered' out by the thermal mass of the E61 & portafilter, when the water actually starts to enter the puck. In electronics, I think it would be like a capacitor smoothing out AC ripple.

One almost needs a SCACE *and* a group thermometer to see the relationship between both on their actual machine. But I'm guessing that the puck is not seeing the big bump shown on the thermometer.


Postby Bluenoser » Jan 12, 2019, 4:41 pm

HRC-E.B. wrote:.Sounds to me like water in the HX quickly rises in temp to above brewing temp, and that, yet, group tends to idle colder and not recover quickly.

I wonder if this is going to be a real down-side to the PID designs in HX. Much longer recovery times between shots. This means that if you planning to have a group of people over and make up to 8 shots, that it will take significantly longer than on older HX designs without an aggressive thermosyphon.


Postby HRC-E.B. » Jan 12, 2019, 6:39 pm

How would a cold group temp be a PID problem if the boiler recovers to its desired temperature quickly. All the PID does is lessen temp swings in the boiler temperature. Assuming that the PID setting is equal to or near where a pressure stat cut off point would be (ie., boiler pressure kept the same), how is the PID affecting recovery time and group temp?

I'd agree with you if PID resulted in lower boiler temp, but I just don't see how that's the case?


Postby Bluenoser » replying to HRC-E.B. » Jan 13, 2019, 9:31 am

Sorry.. I wasn't clear at all.. You are right.. it has nothing to do with the PID, but the overall system design in the newer PID units. To try to eliminate flushing, the designers have added, what I call, an aggressive thermosyphon system (with a small opening in the restrictor). That seems to eliminate flash boiling and the need for most flushes. But, it means the water in the thermosyphon is not able to rebound as quickly as TS designs that have a larger opening and require small flushes. In fact, I would say that on my HX/wPID it is even more necessary to have an external thermometer to determine when the machine has rebounded fast enough for the next shot. From what I read, this might also be present in PID HX designs other than the Profitec.


Postby HRC-E.B. » Jan 13, 2019, 12:43 pm

Thanks for the clarification. If indeed the addition of a PID was accompanied by a smaller restrictor in the TS system, then the comment makes total sense.

I can't comment on the size of the TS restrictor in my PID'd Rocket, since I simply don't have the info, but its behavior and slow grouphead temp rebound suggests that it has a lot in common with the new Profitec.

For what that's worth, as long as the E61 isn't stone cold and based in my understanding that on the external thermometer, the most significant metric is the temp of the temperature of the water actually flowing during the extraction (which I assume is a further 3 degrees cooler at the puck), then I seem to be able to manage my extraction temps recently in spite of this issue.

Would need a scace to confirm with precision...

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Postby Radio.YYZ » Jan 13, 2019, 9:40 pm

This is very interesting because my non pid 500 i experimented with the restrictor size and i did three sizes: 3/32 = 2.381 --- 7/64 = 2.778 --- 1/8 = 3.175.

I measured the holes with a caliper to get mm exact readings and i got: 2.24mm, 2.6mm, 3.15mm.

The difference between the pid pro500 and non pid inside besides the restrictor is also the upper group inlet tube, the tube is wider, which maybe by design to create somewhat of a pressure at the restrictor, it is basically a small nib soldered into the outlet and it is 2.25mm. One can drill a hole into it to increase it but i am not certain how the machine would change (If i had to bet, i would guess the recovery times will be shorter, i.e 5 mins and you may need a bit of a flush for the first shot).

For me i wanted the restrictor to decrease in drop of intrashot temperature and to minimize flushing. I found at 2.25 the recovery time was higher than 5mins (same results as you). If it were me i would time the recovery and wait 6 mins, then 7mins.. etc until you find a good balance. After warranty maybe drill a hole to see how that works out for you.

I settled on 2.6mm for my restrictor and so far i am having good results, my intrashot temperature delta (ignoring the hump) ranges beteween -1.5F to 1.5F, for secondary shots its about -1.5 to -4.5F - The secondary shot delta seems higher because the starting temperature from the thermometer is of water that is not flowing.

Taste wise all shots are very similar.

From your comments bluenoser, seems like i made the right decision to not get the pid 500 and just stuffed a thermosyphon restrictor myself.
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