another_jim wrote: In a saturated or thermosyphon group, you are dealing with very slow flows induced by thermal gradients. Perhaps this amplifies small manufacturing differences.

Loving this stuff ... Thank You!

Quick question: are the thermal gradients you refer to:
a) from boiler to group,
b) from boiler to basket bottom (boiler thru puck), or
c) from puck top to bottom (all puck), or
d) all of above, depending upon where the manufacturer tolerances cause the greatest sensitivity in temperature in the cup (if this is the answer, can you give more thoughts on where that is?)

Again, Thank You and Cheers!!

From the hottest to coldest spot where the brew boiler water reaches; i.e. from the brew boiler's heater to the most exposed part of the group where there's water. On the E61, that's the neck of the group; on the LM groups, it's the entire top surface of the bell.

Yeah, don't know why all of the machine makers boast about their PIDd dual boiler machines, especially with E61s, when they have the temperature sensor in the boiler instead of in the group head. Thermal control of an E61 at the boiler is like holding your garden hose 10 feet back from the nozzle and thinking you can aim it were you want it! The cool end of the system is what needs regulation the most.

Since E61 thermosyphon systems lack feedback where it counts, I suspect they must design the system for the coolest, highest heat exchange environment expected so that they can cover all of the design space. What that does for every other situation, and most of the time, is to drive the group head too hot.

However, after doing the thermometry; I would say the simplest way to adjust the offset is to measure the group at the neck. Use a sticky pad to glue on a naked TC. It will read at the initial shot temperature (once the basket with the TC fills) and the temperatture will climb 1C to 2.5C, depending on flow rate and shot length over, the course of the shot. The group is so heavy that it determines shot temperature. Adjust you offset accordingly.

We are posting the PID setting manual. The link and details will be up by end of day.

Good to see the PID settings manual and your guiding comments up on the Bianca review page. Very useful and yet another opportunity to adjust and observe...
Thanks also for the input on TC location - kind of logical given the E61 thermosyphon flow path - I had noticed the TC housing location on your videos. I'll get that set up over the next week or so and undertake some recording and (probably) adjustment.
It may be that quite a few Bianca owners will alternate between longer profiling shots and those in the 20-30 second area, depending on their household demands and the opportunities to try some new roasts and techniques. So some knowledge of individual machine group temperature and how to best adjust could become part of the process.
I take on board the fact that the thermosyphon will take some time to adjust the temperature of the heavy group and that in turn is going to determine shot temperature, especially on slower flow rates.
Just to keep some perspective, I have to say that I don't regard this learning curve and adjustment process as resulting from any particular production or design defect. The Bianca has already produced a lot of enjoyable coffee for family and friends. Reliability and repeatability matters when a machine is the only source of espresso in a house, but there is still a valuable space available, to learn technique and to adapt and improve on a suitable device and on a suitably humble barista!

Tonefish wrote:Yeah, don't know why all of the machine makers boast about their PIDd dual boiler machines, especially with E61s, when they have the temperature sensor in the boiler instead of in the group head. Thermal control of an E61 at the boiler is like holding your garden hose 10 feet back from the nozzle and thinking you can aim it were you want it! The cool end of the system is what needs regulation the most.

Since E61 thermosyphon systems lack feedback where it counts, I suspect they must design the system for the coolest, highest heat exchange environment expected so that they can cover all of the design space. What that does for every other situation, and most of the time, is to drive the group head too hot.

Putting the sensor in the group is not so simple. It would cause a big overheating after power on. Simply because the heavy exposed group cant keep up in comparison to the boiler water which heats really easily. The heating element would keep on drawing full power untill the group is at set point causing it to boil.

On the other hand the thickness and length of thermosyphon tubes are "simple" phisics and the engineers can calculate the offset between boiler and group in a controlled environment. You as an enduser can then adjust this offset to fit your personal environment.

It might seem more complex, but its for a good reason and there is a lot of know-how about these physics since they are used for about 70 years now in espresso machines.

Having a group temp sensor is possible but would either require a lot more electronics, to prevent overheat during warmup, or a second sensor in the boiler to limit boiler temp during warmup.

Beaniac wrote:Putting the sensor in the group is not so simple. It would cause a big overheating after power on. Simply because the heavy exposed group cant keep up in comparison to the boiler water which heats really easily. The heating element would keep on drawing full power untill the group is at set point causing it to boil.

An HX set point is always above boiling point, so that is not a problem, but I agree that there would also need to be an upper limit beyond which the boiler will not go during warmup. It's the eventual overheating by the passive system that I'm wanting to eliminate. It would probably be good to have that upper setpoint above boiling point even for the brew boiler, to warm it up faster .... within reason. PID controllers should be able to handle this.

On the other hand the thickness and length of thermosyphon tubes are "simple" physics and the engineers can calculate the offset between boiler and group in a controlled environment. You as an enduser can then adjust this offset to fit your personal environment.

The problem is that you'd have to keep resetting it. It doesn't work well because it is passive and it is designed for a range of environments where it only hits the target for a small subset of the environments. It can be done better.

It might seem more complex, but its for a good reason and there is a lot of know-how about these physics since they are used for about 70 years now in espresso machines.

Having a group temp sensor is possible but would either require a lot more electronics, to prevent overheat during warmup, or a second sensor in the boiler to limit boiler temp during warmup.

Yes, I have found this engineering very impressive especially for its day. I'm sure there is improved technology available today, so why not apply it?

Here's a fun recipe for light roast lovers. Turkish grind, lowish dose (8 grams in a single or 16 in a double). Demitasse brew ratio, i.e. 7.5 parts water to 1 part coffee. Preinfuse at 2-3 bar for 25 seconds (you should see a slow drip towards the end), then finish the shot at 8 bar declining towards 4 as you get close to your brew target and need to slow the flow.

Think of this as a very high tech clever dripper, with the preinfusion being the steeping part, and the rest of the shot the brewing part. Since the grind is so fine, you only need a short steep. This is why you want to keep the dose low, so you don't need a longer preinfuse to soften up the puck.

I tried one of the Gesha Village coffees, the lowest scoring Omo lot (I'm working my way up the ratings). It was lovely: really sweet florals with a tiny hint of Maillards and caramels in the background. Beat the pants off the brewed version, the regular spro, or the long preinfusion 3:1 lungo spro.

I may end up looking like a right fool if someone can pull off this recipe with a $15 mochapot; but somehow I doubt it would be all that easy.

I haven't been doing regular review posts, since I've been exploring the monster sized brewing state space of the Bianca (i.e. the various combos of grind, dose, pressure, temperature, and brew ratio). If there's more gold in them there hills, the Bianca becomes the ultimate hobbyist machine. If this enlarged set of brewing possibilities doesn't rock people's worlds, the Bianca is a beautifully built, easier to use alternative to a commercial spring lever machine. A great buy either way, but an entirely different review for Dan and me to write up.

Received my new Bianca today, arrived safe and sound. Packaged well, good documentation, really beautiful machine!

Didn't have much time to play with it, bought a new bag of Gimme Coffee Leftist Espresso, using my Baratza Vario grinder. (Possibly upgrade there in the future) Tried manual preinfusion with the paddle, probably didn't use enough pressure, as I never saw it start to drip after 15 sec or so, but then went to full pressure and got a nice shot. I'm sure there is a ton of room for improvement, but it's still better than anything I could pull on my Expobar Office Pulser. I have the steam boiler dialed all the way up to 1.75bar, and I have tons of pressure at the wand with the larger 2 hole tip that shipped installed on the machine. Here's the 2nd capp I pulled on my Bianca, it will only get better from here!

I guess you're OK with the steam, judging by the latte art (I'm seriously envious)

Like I said, second jug of milk steamed- lots of room for improvement but so easy out of the gate! I love it coming from my Expobar. I'd turn it up to 2 bar if I could!