Olympia pressurestat problem

#1: Post by **mixuala** » August 8th, 2018, 9:30 pm

I've just finished a 220V restore/conversion on a pasquini Livietta/Maximatic. But I'm having problems adjusting the system to get good results. It's my first machine and I'm still trying to learn how to make shots, but my initial attempts produced no crema.

I think the problem is in the pstat. I used a water pressure gauge and saw that I couldn't even get a few PSI on it at the highest setting. I also measured the water temp at brewing and it was peaked at 170F. If I manually trigger the micro switch on the pstat I can get more pressure.

It's there a proper way to adjust the pstat? Am I going down the right path?

#2: Post by **drgary** » August 9th, 2018, 10:01 am

Here you go, from the terrific Orphan Espresso series.

If you can't get the old pressurestat to work you can replace it with a Mater or similar with the same fitting size.

August 9th, 2018, 11:23 pm

Thanks. Great video--now I know that my spring is bent out of shape and way too "long" for the job.

#4: Post by **wsfarrell** » August 10th, 2018, 1:24 am

I've tried the Orphan Espresso trick on a couple of the older-style pressurestats. It worked, but resulted in VERY small increases in pressure. I'd strongly recommend the Mater.

#5: Post by **drgary** » August 10th, 2018, 1:34 am

I did the mod on my Cremina's pressurestat and it now works just fine. It's worth a try.

#6: Post by **drgary** » August 10th, 2018, 1:37 am

mixuala wrote:Thanks. Great video--now I know that my spring is bent out of shape and way too "long" for the job.

To be clear Doug is suggesting modifying the tab that activates the microswitch, not the coiled spring.

#7: Post by **OldNuc** » August 10th, 2018, 9:08 am

The spring is shot. Will always trip off at low/no pressure.

August 10th, 2018, 10:32 am

For anyone who hasn't modded one of these when you spin the adjustment wheel all the way the spring looks very distorted and more worn out than it actually is. With the mod you may be able to readjust so it doesn't look all bunched like that -- but more significantly you'll have that rugged old pressurestat working for some additional years.

#9: Post by **OldNuc** » August 10th, 2018, 11:42 am

Once the spring is stretched and the coils forced off axis the pressurestat is never going to have a decent deadband and probably not hold setpoint. Tweaking the lever on the microswitch is a possibility though. Cutting the spring down in length makes it stiffer which will also cause deadband issues.

Cranking the adjustment to the point the spring buckles is the end of the adjustment. That spring has been stretched in an attempt to make it longer.

#10: Post by **drgary** » August 10th, 2018, 12:00 pm

My experience having done so is that my Cremina holds temperature well. I have the temperature set low enough that I use double pumps to heat the group with water and bring it to brew temperature. Deadband hasn't been an issue, and I don't know if it's particularly important in this case. I'm a stickler for tight deadband in other machines where the pressure setting is more closely linked to brew temperature. A case in point is my Conti Prestina that I have set up with a PID digital temperature controller. Added: For a Maximatic, brew temperature starts high until you do a cooling flush to get within range, so again, I don't think that tight deadband is crucial on these.

I've seen a number of Cremina pressurestats where the spring looks distorted that way and wonder if the adjustment range on the mechanism isn't closely calibrated to the length of the spring, since when it is in range it doesn't bunch up. So I wouldn't assume that the spring has been stretched. These tend to get that ugly look all on their own and still may be repairable. My 2 cents anyway.