ShooterMcGavin Senior Member Joined: 17 Feb 2012 Posts: 53 Location: SoCal Expertise: Just starting
Espresso: N.S. Oscar Grinder: Preciso
Posted Wed Sep 26, 2012, 6:49am Subject: NS Oscar - To Mod or not to Mod? (+ a couple noob questions...sorry)
(While the Oscar is a great beginners HX machine, a couple things have peaked my interest in regards to improving its performance:
Pressure: From what I understand, factory setting has brew pressure at a maximum 15 bar OPV Mod - Worth it? It appears a few people have felt the need to do the mod and this website even offers a kit (http://www.elektros.it/en/oscar_modification_kit.html), However, nixter (Click Here (coffeegeek.com)) argues that brew pressure is regulated by grind and dose and an OPV would be unnecessary.
Vacuum Breaker From what I understand, it's necessary if you plan on putting the Oscar on a timer. Is there a guide/instructions on how to do this mod? I have a tendency to screw things up when tampering with mechanics...
Gauges (thanks for the link Helen!) - This youtube video shows an Oscar with pressure gauges: http://youtu.be/J_xr3ywD0FQ May be novel, but I think it's neat. Again, I have no idea where to begin if I want to attempt this mod.
PS: (warning: really noob questions below)
What is this red tube, and is anything supposed to come out of it (when I backflush, water only gushes out of the clear tube on the right)? Here's a picture of it with a blue arrow pointed towards it: http://i.imgur.com/ToImG.jpg
I have a sirai p-stat. When I adjust it towards the (+), does this increase boiler temperature, therefore increasing brew temperature? Does it also affect brew pressure?
Posted Wed Sep 26, 2012, 8:02am Subject: Re: NS Oscar - To Mod or not to Mod? (+ a couple noob questions...sorry)
A: is the neplax, or expansion valve. Which is an OPV, although I don't believe it's adjustable on the Oscar (I know it's not on my Ellimatic). Stick the blind basket in and run the pump too long and you should see something come out of it. Generally, you don't want to. The OPV mod I've seen puts the OPV on the cold water side of the HX, rather than on the hot water side. The mod that was extensively documented on HB for adding an OPV to the cold water side of an Ellimatic was designed to dump cold water, rather than heated water, back into the reservoir, rather than into the Elli's tiny drip tray.
B: On HX machines, the pstat controls boiler pressure (and hence temperature). It will not affect brew pressure, as that's controlled by the pump, not the boiler pressure. The effect on brew temperature is a little more complex. A higher pressure (ie. hotter) boiler temp will heat the water in the heat exchanger tube faster. So you'll need to do cooling flushes more often and the 'water dance' will be more energetic and probably last a little longer. Unless the boiler is so hot that it manages to superheat the water from the reservoir in the time it takes to pass through the tube, you'll still have decent brew temperature. A higher pressure boiler makes it easier to pull a larger number of back to back shots, but it's a balancing act between recovery time and excessive flushing.
Coffeenoobie Senior Member Joined: 11 Dec 2011 Posts: 2,372 Location: PNW Expertise: I like coffee
Espresso: N S Oscar Grinder: Vario W
Posted Wed Sep 26, 2012, 9:56am Subject: Re: NS Oscar - To Mod or not to Mod? (+ a couple noob questions...sorry)
When Chris Coffee gets the vacuum breaker with the tube in I plan to do this as well as add the glacieurs from musica. See Márcio's thread at home-barista. I am thinking of adding the gauges as well.
You really do not need a "kit" to add one. All you need are two compression fittings to match the copper tube from the boiler to brew head, a 90 deg fitting that has the same inlet and outlet (the straight through side of the "T") and a threaded hole to fit an elbow and a Vac breaker. Assemble as shown in the first pic of my thread, use a tubing cutter (hack saw etc but a tubing cutter is easiest and neatest) remove a section of tube so that the ends of the tube fit into the compression fittings of the T and tighten everything up.
or any generic breaker will work, just keep an eye to size.
I also added a "drip tray" and cover over my instal on my Oscar so that it contained any water from spraying around inside Oscar. I think I used a SPAM can bent to fit YMMV!
Also, I never had an issue of over pressure on Oscar and I really did not miss the gauges and now that I am dialed in on my current machine, I don't use them much at all though they are both there.
In real life, my name is Wayne P.
Feed the newbs, starve the trolls and above all enjoy what you drink!
Coffeenoobie Senior Member Joined: 11 Dec 2011 Posts: 2,372 Location: PNW Expertise: I like coffee
Espresso: N S Oscar Grinder: Vario W
Posted Wed Sep 26, 2012, 10:54am Subject: Re: NS Oscar - To Mod or not to Mod? (+ a couple noob questions...sorry)
I think I would like the gauges but I believe that Marco said that the musica glaciers made the most difference in the Oscar. I just need someone go in with me to order them because they have a 25 dollar min order and the parts are cheap.
Coffeenoobie
Buying advice: GRINDER GRINDER GRINDER. Don't cheap out on the grinder. My coffee treasure map... Click Here (maps.google.com)
Posted Wed Sep 26, 2012, 4:24pm Subject: Re: NS Oscar - To Mod or not to Mod? (+ a couple noob questions...sorry)
Coffeenoobie Said:
I think I would like the gauges but I believe that Marco said that the musica glaciers made the most difference in the Oscar. I just need someone go in with me to order them because they have a 25 dollar min order and the parts are cheap.
Coffeenoobie Senior Member Joined: 11 Dec 2011 Posts: 2,372 Location: PNW Expertise: I like coffee
Espresso: N S Oscar Grinder: Vario W
Posted Wed Sep 26, 2012, 5:05pm Subject: Re: NS Oscar - To Mod or not to Mod? (+ a couple noob questions...sorry)
They are restrictors that help the temp in the group stay more stable. Helps the thermosiphon. Musica comes with them in the same group head and boiler that Oscar has. They are cheap like $2.50 each and you only need 2 and NS requires a 25$ minimum order. Mario talks about them in the thread. He said that on a very slow pour the temps spike way up. I really want to try them. That is one of the mods I want to do when I take my oscar apart for the deep scale job.
Coffeenoobie
Buying advice: GRINDER GRINDER GRINDER. Don't cheap out on the grinder. My coffee treasure map... Click Here (maps.google.com)
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