Recommended Cremina pressurestat setting

[Fullsack]

Another tip is to pull shots with boiler pressure slightly reduced, between 0.7 and 0.8 bar. The Cremina maintains boiler pressure between 1.0 and 0.7 bar automatically. It might seem that high water pressure is better, but the work in extraction comes from the lever, not the boiler. Opening the steam wand to drop the pressure down a bit will help the Cremina work more as it was designed.

Actually Dan and I just did a pressure test on the machine a couple weeks ago. The Cremina 67 does not have a pressure gauge on it but we were able to hook one up right off the top of the boiler.

There is a thumbwheel at the base of the pressurestat that allows you to adjust. I have decided to keep mine at 1.1-1.2


We found that the machine is very stable with its pressure. We did a couple tests to see how much pressure fluctuated between cycles and it all stayed within a .1 range. At the range we picked you get great steam and solid pressure for your pulls.

It appears that Steve, in his restoration thread and Markus from the Olympia factory have a different take on the ideal for the setting of the Cremina pressurestat. I assume there is no hard and fast rule, but rather some trade-offs. Would someone enlighten me as to what they are? Thanks.

[timo888]

I have my Cremina's p-stat quite low. With the Cremina, I am less interested in minimizing intra-shot temperature fluctuation than in being able to pull shots whose average temperature over the course of the extraction remains at the cooler end of the range. I also want to limit inter-shot temperature creep for those times when four consecutive shots are needed.

For a cooler brew temperature, run the steam till the light comes on and then some, and then pull the shot. For a hotter shot, wait for the light to go off and then pull the shot.

The main tradeoff of a dramatically lowered p-stat is that the steam is not as dry, especially when the boiler is full. There is plenty of steam. The other tradeoff is that the preinfusion has to be manually assisted with the lever, since the water enters the group more gently when the pressure is lower. I tend to do a ~10-second preinfusion to swell the puck and warm it. There is a definite benefit to the water hitting the puck gently: if the water hits the puck roughly it can disturb the puck's surface.

Regards
Timo

[roadman]

I change the Cremina's pressurestat setting depending on the beans I'm using. Lower pressure for darker roasts, higher pressure for lighter roasts. If I don't the darker roasts tend to burn and the lighter roasts tend to be too sour.

I'm curious if anyone else is adjusting the p-stat on a regular basis. I'm not sure if I've stumbled onto a good little trick for maximizing flavor or am simply compensating for operator error, or maybe a little bit of both.

Jon

[timo888]

I change the Cremina's pressurestat setting depending on the beans I'm using. Lower pressure for darker roasts, higher pressure for lighter roasts. If I don't the darker roasts tend to burn and the lighter roasts tend to be too sour.

I'm curious if anyone else is adjusting the p-stat on a regular basis. I'm not sure if I've stumbled onto a good little trick for maximizing flavor or am simply compensating for operator error, or maybe a little bit of both.

Taking the Cremina's hood off to adjust the p-stat screw is not something I'd recommend you do frequently on an ad hoc basis. I suppose it would increase wear-and-tear on the machine generally and the p-stat screw itself. You can accomplish much the same thing using the steam knob. Once you have set the pressure range with the p-stat screw, you can lower the temperature for a specific roast by running steam till the heating element light comes on. Right at that point the water is at the coolest point in the cycle. Then pull your shot. Conversely, even with a lowered p-stat, you can pull a hotter shot by waiting to pull the shot until right after the heating element light has gone out. Still not hot enough? Give the lever a few half-lifts to syphon hot water from the boiler out to the group.

Of course, a manometer would make this routine less of a Night Flight --a vintage book by St Exupery that a lever enthusiast sans manometre is sure to enjoy.

Regards
Timo

[roadman]

Taking the Cremina's hood off to adjust the p-stat screw is not something I'd recommend you do frequently on an ad hoc basis. I suppose it would increase wear-and-tear on the machine generally and the p-stat screw itself. You can accomplish much the same thing using the steam knob. Once you have set the pressure range with the p-stat screw, you can lower the temperature for a specific roast by running steam till the heating element light comes on. Right at that point the water is at the coolest point in the cycle. Then pull your shot. Conversely, even with a lowered p-stat, you can pull a hotter shot by waiting to pull the shot until right after the heating element light has gone out. Still not hot enough? Give the lever a few half-lifts to syphon hot water from the boiler out to the group.

Have no fear, I only do this when I run out of good beans and have to make up the shortfall with the freshly over-roasted beans available at the local coffee shop. Still curious to know if anyone else has had a similar experience with the pressurestat.
Jon