2 ?'s - Intrashot temp stability and intershot overshoot

[lessthanjoey]

First, thanks to all - this board was a great resource when I was deciding on purchasing my Mini V2!

The questions:
1) During a shot the set temperature light always starts blinking (registering, i assume, a 0.5C temp drop). However, then the next light will go out, and the next, and so on. It seems like the boiler temperature actually drops several degrees while the shot is being pulled. Niko's video on temp stability shows the same thing, but his portafilter temperature measurements are solid (or if anything rising) through the shot. What's going on?

2) A couple of times now I've switched between 93C and 95C and seen the following. The machine had been indicating stable at 93C (all solid lights to that point) and when I switched to 95C the new lights also came on solid immediately - requiring no further heating of the water. Doesn't this mean it had been 2C too hot at 93? The machine doesn't seem to indicate temperature too high, so how do we know that it's *low* enough?

Thanks!
Joe

EDIT:
this post:http://www.s1cafe.com/phpBB3/viewtopic.php?f=35&t=602 explains the first issue?

[JohnB]

2) A couple of times now I've switched between 93C and 95C and seen the following. The machine had been indicating stable at 93C (all solid lights to that point) and when I switched to 95C the new lights also came on solid immediately - requiring no further heating of the water. Doesn't this mean it had been 2C too hot at 93? The machine doesn't seem to indicate temperature too high, so how do we know that it's *low* enough?

I saw the same thing today when experimenting with different temps on a new blend. I ignore it & do a flush so the lights start dropping & when it comes back up I know I'm where I want to be.

[chas]

First, thanks to all - this board was a great resource when I was deciding on purchasing my Mini V2!

The questions:
1) During a shot the set temperature light always starts blinking (registering, i assume, a 0.5C temp drop). However, then the next light will go out, and the next, and so on. It seems like the boiler temperature actually drops several degrees while the shot is being pulled. Niko's video on temp stability shows the same thing, but his portafilter temperature measurements are solid (or if anything rising) through the shot. What's going on?

The temperature probe is near the back of the boiler in the same area where the cold water comes in.