danno wrote:Another tip is to pull shots with boiler pressure slightly reduced, between 0.7 and 0.8 bar. The Olympia 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.

srobinson wrote: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.

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

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

roadman wrote: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

timo888 wrote: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

I use 1.0BAR as the max pressure and .80 when the boiler light will turn on. This yields a very fruity and smooth profile. I've tried lower, but then you risk sour flavors. I've also tried higher, but then there is risk for bitter flavors. The more important factor is that the higher the pressure, the greater the flow of espresso being forced through the puck.

I've used the lower pressure for awhile and can get more caramel like flavors, but then the fruitiness seems muted and again you're going to have a sour shot or two if you don't allow the machine to warm up. Pressure is highly dependent on personal preference.

I'm using a cremina, an Ashcroft gauge mounted to the boiler cap and 2 kilos of Intelligentsia beans for testing. Here are my observations for two common scenarios:

1. Serving espresso immediately after warm-up
2. Waiting approximately 30 min after warm-up

The temperature of the grouphead impacts the espresso production more than the default pressure. In scenario 1 I'm able to pull up to 6 double espressos before the grouphead overheats. Scenario 2 I can pull shots as-is, but they need to be pulled quicker and are more prone to being bitter. Using a cold wash cloth on the grouphead can bring the temperature down considerably, but this must be repeated for each new shot.

As the beans get older and lose CO2, I adjust the grinder on my Mazzer 3-5 clicks finer.

Here is my procedure: At 1.0 BAR the machine shuts off. I open up the steam wand until the light turns on if not exactly at 1.0 already. I count to 15-20 seconds and this drops the pressure between .95 and .90. I lift the handle 1/2 way up to lock in the portafilter and this drops the pressure to .85, then I pull the shot. The boiler turns on again at .80 and I want to have my shot pulled by this point in time. For each new shot, I open the steam wand to reset the pressure, then again count to 15-20 seconds.

I don't like running a lot of water through the head, as I feel like it overheats.

I cycle mine between 0.7 and 0.8 which is what was recommended. It seems a very good trade-off setting and works well with with a wide range of beans. Even a drift up to 9.0 is noticeable as a deterioration. But I suppose it depends on what beans one is using and quite possibly on the ambient temperature as well. In the winter I tend to leave the portafilter locked in between shots, but remove it and let it cool in hot summer weather.

nmalnati wrote:I use 1.0BAR as the max pressure and .80 when the boiler light will turn on..

MichealBenis wrote:I cycle mine between 0.7 and 0.8 which is what was recommended. It seems a very good trade-off setting and works well with with a wide range of beans. Even a drift up to 9.0 is noticeable....

Am setting pressurestat on a 2003 model Cremina.

It's been pretty easy to set when it comes on at .75 - but max pressure is at 1.15 bar, and at the moment I haven't figured out how to lower the top end - or change the range.

There is a screw down in a hole in one end of the pressurestat, turning that screw changes when it comes on. However, the range shifts also when you change the entry point - I don't see anything else to adjust, nor have I so far been able to find a tec manual, or instructions. There's a good bit out there on 67 models - which seems to be what most of this thread is about. Not too much out there on 2003 models, either that or I am missing it as I scan search items.

If someone would clue me in as to how adjust either the range or the max pressure on a 2003 or later model Cremina, I would appreciate it.

It sounds as if you have the later Mater pressure stat (the earlier ones have a brass wheel rather than a screw in a recess).

On both models you only set when the pressurestat switches off. You can't set the range. The new Mater pressurestats have a range of approximately 0.1 bar. It sounds like there may be something wrong with yours, but for the time being I'd try turning it down until it switches off at 0.8 bar and see how that affects the range (if at all).

Fingers crossed for you that a lower setting reduces the range....

Cheers

Mike

Thanks for your prompt response, Michael.

There must be a problem with the pressurestat.

I've shifted it up over .8, down to .7

At whatever setting, there is a range of about .4 bar between shut-off and turn on.

Oh well, it looks like I'm going to need a new one.

Appreciate your pointing me in the right direction.

Best regards

Ken