Hey all. I've been a bit disappointed overall with my home espresso performance thus far. I make the occasional great shot but not often enough. In fact it's really rare. I find myself making lattes to hide this fact. Anyhow I took a couple readings today, one from the group head using a Taylor digital thermometer and an insulated (double walled) glass cup. The average reading i got was between 180-190 degrees. A bit too cold. I then screwed a gauge on the steam tip and took a pressure reading of 20 psi. I was under the impression that only 19psi is required for the optimal brew temp. Should I just turn up my Pstat a little and see what happens? The Pstat adjustment is the one under the yellow tab on the Sirai correct?

Oscar with Sirai Pstat.

I dunno about the Oscar too much, but 20 psi is about 1.4 (ish) BAR. Fairly high, and about 228 degrees Fahrenheit. Either you're losing some heat by the time it exits the group, or your HX's (Oscar?) are inefficient or scaled, or your measuring kit is somehow wrong or off.

Go here to learn how to adjust the P-stat.

well I bought it new about 14 months ago and haven't done a descale yet so maybe it's time.

20psi ~ 1.3bar
16psi ~ 1.1bar maybe a more reasonable boiler temperature.

Re Insulated cups: Unless you follow an identical protocol every time, readings with a thermometer in a cup will vary considerably.

Preheat your cup by boiling water in it in a microwave for 30s.

Be sure that the group has recovered from the last test. > 15minutes should be good.

Flush the same measured volume cooling flush from the group.

Try to achieve the same interval from emptying the cup to starting the flow.

Something in the 180-190 range does not seem too far off the mark.

one BAR is equal to nearly one atmosphere (14.7 psi @ sea level, on a Tuesday, mid afternoon, 72 degrees F, 30% humidity, looking West, yada yada yada...). I use 14.5 psi per BAR for ease of calculation, and it gets pretty darn close.
20 /14.5 = 1.38-ish, or nearly 1.4, 16/14.5 = 1.1, and probably closer to what you want in the boiler. Find out what flushing the group for a few seconds does. It could be that the Oscar (and again, I know very little about that machine) doesn't efficiently heat the group, and that the group is cooling off the water as it passes through. It could also mean that your third shot is flashing to steam, if that's the case!
I'd bet that if you're using decent water for fourteen months, it doesn't need descaled quite yet. If you're not using decent water, then that could be the root of more problems than just that one soon.

well I've descaled the machine and then run some more tests. generally all in the low 180's. I'd like to try adjusting the Sirai a little, as I've never tried this could someone tell me which direction I turn and by roughly how much?

I agree with Ian that the temperature sounds about right, but to answer your question, clockwise = more tension on spring = higher boiler pressure. The Sirai requires lots of turning compared to the ultra-touchy MATER and CEME. It's been awhile, but I would start at 1/2 turn and check with a pressure gauge.

cafeIKE wrote:Something in the 180-190 range does not seem too far off the mark.

HB, are you sure about the counter clockwise = higher temp? I turned it one full turn then tested my steam and it's down to 18psi now.

You know the old saying: Lefty loosey, righty tighty. You can compare against the +/- arrows stamped near the adjustment screw.

Turns out it is counter clockwise to increase pressure/temp and clockwise to reduce. This actually makes sense when you think about it. Loosening the screw means that more pressure is then required to trigger the stat.