atao wrote:i was curious - how do you like the preinfusion functionality? can you tell any difference in ease-of-use (less channeling?) or taste vs. no preinfusion?

i was curious - how do you like the preinfusion functionality? can you tell any difference in ease-of-use (less channeling?) or taste vs. no preinfusion?

The 3-way valve opens when the PID makes a brief pause before the main infusion and a classic "whoosh" can be heard,

Hello Ted

The 3 way valve is open during the delay. This is not a silly question. We spent several months to get a clear answer about which way is better.. We asked several people that have a lot experience in the coffee business about whether the valve should be closed or open. Some people said it should be closed but other said it should be open. We also found both approaches are used on espresso machines on the market. We could not get a clear answer on which is better and why. So we did our own test. Here is what we found.

1) There is no detectable difference on the coffee extraction between letting the valve closed or open during the delay.

2) There is obvious improvement for the coffee extraction with pre-infusion (valve closed or open) than without pre-infusion.

Keeping the valve closed will make the installation much more complicated for the user. It also increases the cost substantially for the controller. So, we decide to let the valve open.

It seems that for pressure delay based pre-infusion, keeping the valve closed is the easier approach (using pressure arrester, It will be difficult for it to open without electronics) For pump pulse based pre-infusion, keeping the valve open is the easier approach. But from the basic concept of why pre-infusion is needed, leave the valve open or closed will make no difference.

Thanks,

Suyi