I apologize for what likely is a repeat, but ....

Can some one explain "offset" and provide me with some help for my new Alex Duetto 3.

This is how I understand it: The boiler temperature displayed on the front of the unit (200 for the brewing boiler) is not the actual boiler temperature, but is the temperature of the brew water as it hits the coffee. The boiler temperature controlled by the PID is actually maintained at a different temperature so that when it hits the group head it will be the "correct" temperature.

My machine is set up with the factory offset of 18 (does that mean that the boiler is 218 even though though the temperature shows 200F? Or is this number not actually related directly to degrees). I have a Taylor thermometer set into the group head and when I brew (after a 2oz flush) the temperature shows 207-208. I confirmed the thermometer is reading correctly by removing it and comparing it to another digital thermometer.

Or do I have it wrong, the 200 is meant to reflect not the temperature of the water hitting the puck, but exiting the puck. In that case the 207-208 may be what is required and to confirm the offset I would need a Scace thermometer which if I understand how that works, measures the water temperature as it exits the puck.

Thank you in advance!

qpsport wrote:My machine is set up with the factory offset of 18 (does that mean that the boiler is 218 even though though the temperature shows 200F?

I think you have the gist of it. The boiler has to be kept at a higher temperature than the desired brew temperature. The water loses some thermal energy on its way to the group as well as the effect of cold water being pumped into the boiler and even the ambient air temperature. The display shows the BREW temperature you have selected and the offset is "automatically" added to that set temperature to "offset" the temperature differential. It is merely a convenience so that you don't have to do math in your head at 0600 hours when making the morning's first pull.

Randy G. wrote:... The display shows the BREW temperature you have selected...

Thank you for explanation. Can you tell me if the brew temperature is the temperature of the water as it hits the puck, or leaves it? If it is the temperature as it hits the puck, I guess I need to decrease the offset so the water is 200 and not the 206-207 that came from the factory. If on the other hand, it is the temperature of the water leaving the puck, I will just assume that the 206-207 before the puck as set by the factory is correct to achieve the 200 as it exits.

Brew temperature (around 200F) is typically specified as above the puck, but mid-puck or leaving the puck would have a better correlation to taste. As would showing the entire temp vs time graph (instead of a single number).

I have my duetto 2 set to 10 deg offset.
You can check yours by raising your brew temp 1-2 deg, wait 10 minutes, and pull water without a ports filter in. Repeat until the water flash boils. When you hear a flash boil your PID should be reading the temperature at which water boils at your elevation.
If it's not, adjust the offset.