I am finding that the brew temp on my Duetto seems to have too large of an offset. It's factory set at 18F. But after playing with the machine for almost 2 months now, I am consistently finding that of all the different blends I've tried from CC to Metropolis to Intelly to Klatch, they all seem to favor brew temps in the range of 191-198F. This holds true from light to med/dark roasts. My routine is: 1oz flush, grind and prep shot, and about 45 seconds later purge 1/2 - 3/4oz and immediately pull the shot. And this is in a cold basement (65F). One thing that is strange though is that I did the test of setting the boiler to 207 to listen for the flash boil and it did start to hiss a slight bit so I guess my offset is correct. Not sure how to make sense of this. The only thing I can think of is that when the offset was calibrated is was done on a cold machine or with the steam boiler off. I nearly always have mine on mainly for the faster recovery. Unfortunately I no longer have a scace to test it. I know I brought up this topic before but didn't really have much response. Cmon Duetto owners help a brother out! Side note: I was all the way down to 190F pulling some Klatch Belle this morning and it was absolutely decadent! Yes, it is a bit of a darker roast, but Mike recommends that blend at 198F, but for me is was to bitter/ashy tasting at that temp.

My offset is the same, 10 degrees Celsius. Judging by the Eric's group thermometer it should be 11 or 12 degrees for exact results.

Mine is also set at the default 18F. I've considered ordering one of the group thermometers to get it more exact, but there is something to be said for going by taste. Why did you not adjust the offset if you're able to check it, akallio?

I found my offset was too high as well, by default.
I don't remember what i lowered it to, but i set it so that when the display shows 212, that's when it start barely flash boiling. Most of my blends now are happy around 200-202.

I also noticed that the flash boil point on the display does not change with the boiler on or off...right at 212. No flash at 211, small flash at 212, definite at 213.

Mine used to start flash boiling at 207, which indicates to me the machine is 5 degrees hotter than it thinks it is...

Bob_McBob wrote:Why did you not adjust the offset if you're able to check it, akallio?

Because then I would have to walk downstairs to get the Duetto manual from our manual stash. Too much of an effort.

I really don't care if it is constantly 1 degree off. Or if the brew temperature drops always 2 degrees while brewing. What I care about is stability between shots, and having the ability to get a ballpark number for the actual brew temperature. Neither of them requires tuning the offset.

Billc wrote:1. The place the temp is measured is different from the place the water exits.
2. Error exists in electronics. ... If you use in another temperature the temperature will most likely not be exactly the same. In general all electronic components (resistors, capacitors, temperature probes, etc.) have some tolerance of error associated with them.
3. Mechanical assembly. Heating element position, boiler rotation, welding differences all have some differences when assembled. This actually introduces some error as well.

from Scace thermofilter on a La Marzocco GS3

IMO, boiler offset on an e61 double boiler is a guessing game unless the ambient conditions remain invariant.
Eric's adapter isn't.

Recently, there was no heat in our office, the weather was quite cool and a 1500W space heater could not quite cut it. The DB brew boiler temp had to rise 2°F to compensate. Yesterday, they fixed the heat and the boiler temp is now back @ 224°F

And this is in a cold basement (65F).

Now THIS makes a substantial difference.

The benchmark for Alex Duetto performance is here - Temperature study of Alex Duetto

An initial (incorrect) thought might be to adjust brew boiler temps such that regardless of ambient temperature swings (intentional or not) the grouphead temperature remained relatively constant. Off the top of my head, this would result in a slightly higher temperature of brew water presented to the coffee when moving from, say, a 72 F environment to a 65 F space.