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Silvia pressure mod vs. Isomac Venus
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haak
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Joined: 27 Aug 2005
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Posted Fri Dec 2, 2005, 11:39pm
Subject: Silvia pressure mod vs. Isomac Venus
 

I am considering performing a pressure mod on my Silvia (or getting an Isomac Venus). Does anyone know any helpful links to web pages describing the process? Any hints from those of you that have done this mod? Once modified, how would the Silvia compare to the Venus? I read the post on the Venus and am a bit woried about the thermostat problems Marc had after using it for a week, anyone else with these problems?
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mmm_crema
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mmm_crema
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Espresso: Nuova Simonelli Mac 2000
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Posted Sat Dec 3, 2005, 12:59am
Subject: Re: Silvia pressure mod vs. Isomac Venus
 

haak Said:

I am considering performing a pressure mod on my Silvia (or getting an Isomac Venus). Does anyone know any helpful links to web pages describing the process? Any hints from those of you that have done this mod? Once modified, how would the Silvia compare to the Venus? I read the post on the Venus and am a bit woried about the thermostat problems Marc had after using it for a week, anyone else with these problems?

Posted December 2, 2005 link

Well Haak,

I went off the deep end some months ago and did the pressure mod. The results are significant (in my case). I get a consitent pressure to work with that takes alot of stress off of the pump. It makes it easier to get the grind right. The crazy high pressure that comes with a stock unit will plow through just about any grind you throw at it, while the modified pressure keeps you at the best grind setting without choking the thing.
    There should be some instructions here somewhere . . . I can't remember exactly the size of the washer required. . . 16 mm ?  From Crappy-Tire I think.

Emil
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itinerant
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Joined: 1 Sep 2005
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Posted Sat Dec 3, 2005, 1:06am
Subject: Re: Silvia pressure mod vs. Isomac Venus
 

haak Said:

Does anyone know any helpful links to web pages describing the process?

Posted December 2, 2005 link

I guess that you didn't try Google before posting.
"Silvia pressure mod" pulls up any number of DIY web pages


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Luca
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Luca
Joined: 27 Jan 2004
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Location: Melbourne, Australia

Espresso: H: Maver W: FB-80
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Posted Sat Dec 3, 2005, 1:10am
Subject: Re: Silvia pressure mod vs. Isomac Venus
 

The site that everyone refers to about the pressure mod is here.  It should have all of the information that you need.

Beware, at least, that you might inadvertently screw up your boiler (detailed on the pressure mod site) and that the valve might open sooner, letting water dribble out.  This will mean that you will have to run the pump a bit just to top up the boiler before extracting a shot.  This is not an issue if you are running water through the machine to temp surf it, because you will top up the boiler anyway.  It would be mildly irritating if you had PID'd your machine because you would have to top up the boiler and wait for the PID to stabilise things ... although this will probably take care of itself whilst you are grinding and dosing.

I sincerely doubt that there is much noticeable difference between the two machines, except that the Venus looks way cooler and has a pressure gauge of some description.  I suppose that there might be some difference in the fact that the Silvia grouphead is removed from the boiler, whereas the Venus' grouphead is on the bottom of the boiler.  Presumably the Silvia is marginally more temperature stable if not PIDed and the Venus is more temperature stable when PIDed, but will always run a bit hotter after steaming (both machines will).  I'm not aware that the Venus has an adjustable OPV, but go check it out.

I haven't yet done the pressure mod, but have noticed that every commercial machine that I've used is much more forgiving.  I presume that this is a combination of preinfusion and lower pressure.

Cheers,

Luca

 
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Sparkman
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Sparkman
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Posted Sat Dec 3, 2005, 11:03pm
Subject: Re: Silvia pressure mod vs. Isomac Venus
 

If I had a Silvia, I wouldn't suggest changing to a Venus. While I am tending towards the boiler-on-group (like the Venus) design the more I investigate it, it really is a sideways step. The pressure gauge is a nice touch, but I'm not sure the OPV on the Venus is adjustable. It is also on the hot water side, so the cold water injection into the boiler is increased if you lower the OPV setting, hence the boiler temperature will become less stable. Not a good design IMHO. However, it you plan to do a few mods, then I'd pick the Venus as you can pull this into a really thermally stable regime much easier than a Silvia, due to the Silvias separated group head.

In my experience, adding a PID controller to a Silvia will improve the performance beyond sight. However, the boiler-on-group design of the venus will get the group up to brew temp much quicker than the Silvia's separated group will, and it will stay there. In my experience, it will take only two blank shots and you're in the zone pulling shots with sub-1 F repeatability.

So I'd prefer the Venus to work on, compared to the Silvia. Mods would include PID control, putting an OPV in the input feed water line, insulating the boiler and removing the brew feed pipe from within the boiler. Those mods would see you with a temperature stability in the league of the big thermostable machines like a LM, Synesso and the like.  (ie inter-shot repeatability sub 1 F, intra-shot variation around 1 F) . Also these mods will result in a rising temperature profile much like the new LM GS3.

Back on topic, stick with the Silvia, unless you're a mad experimenter like me.

Regards,

Mark.
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counting
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Joined: 8 May 2005
Posts: 823
Location: Baltimore, MD
Posted Sun Dec 4, 2005, 12:32am
Subject: Re: Silvia pressure mod vs. Isomac Venus
 

Sparkman Said:

...I'm not sure the OPV on the Venus is adjustable. It is also on the hot water side, so the cold water injection into the boiler is increased if you lower the OPV setting, hence the boiler temperature will become less stable...

Posted December 3, 2005 link

How is this? Is it because the OPV bypass goes to a place that is less reasonable than in the case of other OPV designs? Just asking, have no idea what the answer is.
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Sparkman
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Sparkman
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Posted Sun Dec 4, 2005, 2:10am
Subject: Re: Silvia pressure mod vs. Isomac Venus
 

counting Said:

How is this? Is it because the OPV bypass goes to a place that is less reasonable than in the case of other OPV designs? Just asking, have no idea what the answer is.

Posted December 4, 2005 link

Here's my take on it. Most OPV's are not used to regulate the brew pressure, but provide an overpressure relief safety function. So under factory intended use it's much of a muchness. However, if you want to use the OPV to regulate the brew pressure to not exceed 9 bar (say), then what will happen will be that the OPV will open above 9 bar and let some water out until the pressure is at or below 9 bar. Quite a few machines have this device before the boiler so that the water controlled by the OPV is at room temperature. This will most likely enhance the longevity of the device, as high temperature operation generally accelerates ageing. However, in the case of the venus, the OPV will bleed off hot boiler water to regulate the brew pressure. That means the extra cold water will have to enter the boiler during the shot to supply both the bleed-off and the shot volume. So you're adding an extra load to your boiler. If the OPV rarely opens, the point is moot. However, in my machines the OPV passes quite a lot of water to maintain brew pressure (I'm using a different --fluid-o-tech-- pump though). For Ulka E5 pumps, the OPV should open for singles and ristrettos, but not really for doubles.

It would be easy to put in a fluid-o-tech pump that comes with its own OPV and solve this design issue anyway.

With that issue aside, I'd love a Venus, as they look great, come with a pressure gauge and should be very amenable to some very effective mods. They probably have a better drip tray than a Silvia as well.
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haak
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Joined: 27 Aug 2005
Posts: 71
Location: Surrey, BC
Expertise: I love coffee

Espresso: Andreja
Grinder: Milano
Roaster: iRoast2
Posted Mon Dec 5, 2005, 11:40pm
Subject: Re: Silvia pressure mod vs. Isomac Venus
 

Mod completed. I used about a pound of beans for testing and can tell you that the taste difference is noticable. A lot less bitter as I can use a bit coarser grind. Hmm. Nice. A bit less crema as well. Not much though. I also found out that ECM put out a machine for 2006 called ECM Botticelli II. This is apparently their second attempt, as the first was put out around 2001. Reason I am mentioning it is because it seems to fit the same class as the Silvia and Venus, except it costs a lot more than either, around CDN$900.
Thank you for the link, and everyone thanks for your help.
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tominoz
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tominoz
Joined: 1 Jun 2006
Posts: 2
Location: Wagga Wagga
Expertise: Just starting

Posted Thu Feb 22, 2007, 3:45am
Subject: Re: Silvia pressure mod vs. Isomac Venus
 

Sparkman Said:

.....insulating the boiler and removing the brew feed pipe from within the boiler.

Regards,

Mark.

Posted December 3, 2005 link

Just a quick Question Mark. If the brew head is attached to the bottom of boiler how can it be fed if you remove the feed pipe from within the boiler? How will this help?

Thanks,

Thomas

tominoz: mylogol.gif
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