shmish Senior Member Joined: 20 Jun 2009 Posts: 27 Location: Vancouver BC Expertise: I like coffee
Espresso: Krup 964
Posted Tue Apr 24, 2012, 7:09am Subject: help with backflushing a NS Oscar
Hi, The Oscar comes with a blind filter and I thought it would be a good idea to backflush it. I've never seen how this is done, so I looked at a few videos on youtube. What I've seen is that while backflushing, the water comes out of a spout somewhere. However, on the Oscar the this does not happen. With the blind filter in place, I turn on the pump and pressure builds but the water is not actually flushed out anywhere (not that I can see). So I'm really not too sure what is happening here, I don't see where the "flush" part comes into play.
germantownrob Senior Member Joined: 2 Dec 2007 Posts: 2,008 Location: Philadelphia Expertise: I love coffee
Espresso: Duetto 3, A Dead Oscar Grinder: Vario-W, Preciso w/Esatto,... Drip: Brazen Roaster: Diedrich IR-1, HT B
Posted Tue Apr 24, 2012, 10:28am Subject: Re: help with backflushing a NS Oscar
There is a tube that is behind the front panel that goes to the drip tray.
I lock in the blind filter and turn pump on for 10sec then turn pump off, sometimes the flow doesn't happen until the PF is unlocked.
After a session of making shots I always do a scrub of the group head then a water back flush, repeat.
Every week I do a chemical back flush. I start by unscrewing the screen and brass diffuser to scrub and soak in cleaning solution along with PFs and baskets. I reinstall diffuser and screen and put a scoop of cleaner in the blind PF basket and back flush the group. Repeat 5 times and then scrub and fresh water flush.
Coffeenoobie Senior Member Joined: 11 Dec 2011 Posts: 2,313 Location: PNW Expertise: I like coffee
Espresso: N S Oscar Grinder: Vario W
Posted Tue Apr 24, 2012, 11:02am Subject: Re: help with backflushing a NS Oscar
Don't forget the portafilter wiggle! I will see if I can find a video to show you. I can't find the one that has the portafilter wiggle. You just wiggle it in holder carefully so that the hot water comes out the sides of the blind basket to help clean off the group head gasket. I backflush with water every session and do the wiggle almost every time.
shmish Senior Member Joined: 20 Jun 2009 Posts: 27 Location: Vancouver BC Expertise: I like coffee
Espresso: Krup 964
Posted Wed Apr 25, 2012, 3:10am Subject: Re: help with backflushing a NS Oscar
germantownrob Said:
There is a tube that is behind the front panel that goes to the drip tray.
I lock in the blind filter and turn pump on for 10sec then turn pump off, sometimes the flow doesn't happen until the PF is unlocked.
After a session of making shots I always do a scrub of the group head then a water back flush, repeat.
Every week I do a chemical back flush. I start by unscrewing the screen and brass diffuser to scrub and soak in cleaning solution along with PFs and baskets. I reinstall diffuser and screen and put a scoop of cleaner in the blind PF basket and back flush the group. Repeat 5 times and then scrub and fresh water flush.
Thanks, I now see the outlet. Similar to you, there isn't any flow for the 10 s that I have the pump on. Once I turn off the pump, there is a short burst like a "pffft" where some steam and a bit of water comes out. There isn't any real flow of water though. Does that sound normal?
faaparasite Senior Member Joined: 19 Jun 2003 Posts: 288 Location: Dallas Metroplex Expertise: I love coffee
Espresso: Bezzera BZ99 Grinder: Mazzer Super Jolly Drip: Technivorm
Posted Wed Apr 25, 2012, 6:50am Subject: Re: help with backflushing a NS Oscar
shmish Said:
Thanks, I now see the outlet. Similar to you, there isn't any flow for the 10 s that I have the pump on. Once I turn off the pump, there is a short burst like a "pffft" where some steam and a bit of water comes out. There isn't any real flow of water though. Does that sound normal?
Yep, that's how it works. If you didn't have the 3 way valve, when you remove the portafilter the accumulated pressure would spray grounds and hot water all over the place. The sound you're hearing is the 3 way valve doing its job.
germantownrob Senior Member Joined: 2 Dec 2007 Posts: 2,008 Location: Philadelphia Expertise: I love coffee
Espresso: Duetto 3, A Dead Oscar Grinder: Vario-W, Preciso w/Esatto,... Drip: Brazen Roaster: Diedrich IR-1, HT B
Posted Wed Apr 25, 2012, 9:03am Subject: Re: help with backflushing a NS Oscar
faaparasite Said:
Yep, that's how it works. If you didn't have the 3 way valve, when you remove the portafilter the accumulated pressure would spray grounds and hot water all over the place. The sound you're hearing is the 3 way valve doing its job.
And when you do a chemical back flush it usually puts more flow through the 3 way valve and tube especially when on the 3rd or fourth press of the brew button. Probably would do the same when doing a water back flush but only loosen the PF and then lock it again then press the brew button, see if you see more flow.
The left side of the group is another tube, that is the opv side and let's off pressure during the shot if it goes higher then what the opv is set at.
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