La Pavoni Professional - first espresso too hot! - Page 2

#11: Post by **mathof** » July 10th, 2014, 5:24 am

neeko1118 wrote:Thanks to all three of you for replying! I tried pulling a shot today. I started it and let it come to .5 bar. Released pressure through the wand for a good amount of time. Let the pressure come up to the point that the machine cut power right around 1.0 bar. I felt the group head and it was only warm. I Pulled the shot and it still came out very hot. Is it possible that the pressure gauge is inaccurate? I understand that this is a more temperamental machine; however, is it possible that it is this hot right from the start?
~Nick

OldNuc's point about giving the group time to act as a heat sink is vital. I usually give the puck 12 seconds of preinfuision time (with the handle up), during which I watch the temperature of the side of the group (to which I have a thermocouple attached) first rise and then fall to where I want it.

Matt

#12: Post by **OldNuc** » July 10th, 2014, 7:31 am

These little gauges are not a paragon of accuracy and drawing a 14psi vacuum on one can cause the pointer pinion to skip a tooth or 2 on the rack or permanently distort the bourdon tube and they do not always show an upscale indication when the accuracy at the desired pressure is grossly inaccurate. Swapping in a known good gauge is one way to check this.

Some amplification of exactly what/how "too hot" is being determined would probably help here.

July 10th, 2014, 10:08 am

homeburrero wrote:Since the OP has two machines, one option to check the suspect manometer would be to temporarily put it on the newer machine and see what it reads.

I ordered an IR temp sensing gun on amazon. I will try switching the manometer until that arrives. I will pull a few shots later today and let you all know how I fare.

July 10th, 2014, 10:12 am

mathof wrote:OldNuc's point about giving the group time to act as a heat sink is vital. I usually give the puck 12 seconds of preinfuision time (with the handle up), during which I watch the temperature of the side of the group (to which I have a thermocouple attached) first rise and then fall to where I want it.

Matt

Yes, I usually wait 10-15 seconds. I do that with the new one as well. With that one I have pulled some, truly, glorious shots. Hopefully my temp gun comes today, if that does not do the trick I'll rig it up like some of you have done here.

#15: Post by **OldNuc** » July 10th, 2014, 11:51 am

IR temp guns are a fail on highly polished metal. You will get some info but it is not that reliable or accurate.

#16: Post by **rpavlis** » July 10th, 2014, 3:13 pm

Temperature sensors need to be far down on the group, because the temperature inside the top of it is forced to be the boiler temperature by physics! Everything inside above the piston is at this temperature. (After it is bled, of course.) By putting sensors farther down you can tell how much heat transfer has occurred to the brewing area.

#17: Post by **wkmok1** » July 16th, 2014, 8:22 pm

To get around the problem of IR thermometers not working well with shiny targets, would soaking a swatch of dark cloth in oil and "paste" it to the group head work? The oil conducts heat and acts as glue.

Winston

#18: Post by **DanoM** » July 16th, 2014, 8:43 pm

wkmok1 wrote:To get around the problem of IR thermometers not working well with shiny targets, would soaking a swatch of dark cloth in oil and "paste" it to the group head work? The oil conducts heat and acts as glue.

First off, I can't imagine how this would look other than kind of ugly, perhaps messy around the edges?

IR thermometers aren't the most accurate measuring systems out there. Typically only a few degrees either way will make a difference in the cup, so having it within 10 degrees or even 5 wouldn't be a huge help past learning the machine. A digital thermometer strapped to the machine with the display visible or out of first sight would probably be far more accurate, useful and probably better looking overall.