# Nuova Simonelli Oscar (Steam) Pressure falling



## enda1 (Aug 2, 2013)

Hi all,

I've semi-recently won a NS Oscar on ebay. I had good stable use for probably 3 months but of late I'm having trouble maintaining boiler pressure, in particular steam pressure. I've cleaned it out with citric acid solution and replaced the grouphead gasket. I've got a pressure gauge to attach to a portafilter which should have arrived at home today in order to check on actual pressure and trend of pressure as steam is released.

What should I look out for and how will I fix my issue if I see that the pressure is dropping off mid steam?

It takes about 30s to 60s of steam release for it to drop to virtually (and sometimes actually) nothing.


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## funinacup (Aug 30, 2010)

The steam pressure isn't related to the pressure at the group, as that is controlled by the pump.

How long does it take to rebuild the steam pressure? Does it only drop when you open the valve or does it happen when the machine is idle too?

Sounds like your element isn't coming on quickly enough. Usually the pressure stat detects boiler pressure so I would be looking to replace this first. If it takes an overly long time to rebuild the steam, then the element could be on its way out.

Sent from my GT-I9300 using Tapatalk 4 Beta


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## enda1 (Aug 2, 2013)

Hmm. I must have a look at this when I get home. I did try and adjust the pstat up to attempt to boost steam. It seemed to work temporarily like for a day or two but then it reverted to its usual pitiful self. The machine is a good few years old - I'd say from around 2005-2007. I'll probably then get around to changing the pstat. While I do that is there a particular one I should go for? Otherwise is there a good fixer-upper who I could get to do this for me as I tend to have little free time and not so many tools?

The steam never rebuilds to 100%. The heating element often kicks in often about 20s of steaming. I usually turn the machine on on a Friday evening and leave it on till Monday morning continuously. (I'm only in this house at the weekends). So it shouldn't be a stabilisation issue either.

(Would this be a recommended pressure stat to replace my perhaps ailing one with?)


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## enda1 (Aug 2, 2013)

To update: I measured the group head pressure today. It rises to above 16bar (the maximum I can read). So the pump should be fine I suppose? I measured it with a pressure gauge attached to a portafilter.


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## enda1 (Aug 2, 2013)

funinacup said:


> The steam pressure isn't related to the pressure at the group, as that is controlled by the pump.
> 
> How long does it take to rebuild the steam pressure? Does it only drop when you open the valve or does it happen when the machine is idle too?
> 
> ...


So I installed a Sirai pstat on Sunday. The problem seems to have been fixed! Yippee! The difference in size and weight between the old MATER pstat and the new Sirai one is comical.

Cheers for the advice.


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## funinacup (Aug 30, 2010)

Glad you got sorted!

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