espressoperson wrote:1. I always flush before placing portafilter to clean the screen and surrounding area (once, then run a pallo brush around the inside edges, then flush again and wipe dry). Also to lubricate piston before pulling first shot. Flushing consistently will still leave temperature predictable. IMO too much flushing will only become a problem if you're pulling many shots at one time and don't take steps to cool the machine down. But for just a shot or two I'd rather have a clean machine given we don't have built in backflushing to help us.

I prefer to clean the dispersion screen/group after the shot (after every shot).

If you do empty flushing just before the shot, very hot water rushes through the group leaving the channel and the inside of the group considerably hotter than the surface of the group (not homogeneous) resulting unpredictible temperatures during the pull. Doing half pulls for preheating (means lifting the lever just to the point the group would release water) means you push water from the space above the piston back to the boiler. Going back with the lever to the bottom position means pulling fresh hot water inside the chamber above the piston from the boiler making heat transfer much more effective than with an empty flush (rushing hot water).

espressoperson wrote:I still do the "half pulls" especially if I want to increase volume.

This is the "other" half pull (Fellini move) . From the top position downwards (during the pull). You are right. It has nothing to do with temp management. See above.

naked-portfilter wrote:If you do empty flushing just before the shot, very hot water rushes through the group leaving the channel and the inside of the group considerably hotter than the surface of the group (not homogeneous) resulting unpredictible temperatures during the pull. Doing half pulls for preheating (means lifting the lever just to the point the group would release water) means you push water from the space above the piston back to the boiler. Going back with the lever to the bottom position means pulling fresh hot water inside the chamber above the piston from the boiler making heat transfer much more effective than with an empty flush (rushing hot water).

I agree that the half pump to preheat is preferable but I will do an initial 2 sec full flush to get the portafilter up to temp. After that it's only half pumps to heat and inserting a cooled portafilter to cool.

I think I get it. Will give this a try. Cheers!