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Thread: Silvia - water flowing back to tank problem

  1. #1
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    Silvia - water flowing back to tank problem

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi All,

    I've tried a few searches and some self help before reaching out, at this point I hope it's me just not thinking of something obvious.

    Basically when I'm trying to pull a shot, I'm getting very low water throughput via group-head, I then noticed that water is heading back to the tank via the return pipe. My thinking is that my OPV might be faulty (stuck open somehow). Looking at the water path, it must be the OVP right?

    I'm guessing my next step would be to remove the OPV and check the components for wear, give it a clean up and see how that goes. Just wanted to get some thoughts before I go beyond my comfort level of disassembly.

    Here are the resources I'm using to arrive at this conclusion
    Commercial link removed
    Rancilio Silvia - pulling fast then slow - Espresso Machines - Page 2 • Home-Barista.com


    My setup: Rancillio v3 with Auber PID (pre-infusion), backflush every week, de-scale every 2-3 months.

    Thanks to anyone in advance who shares experience
    Last edited by Javaphile; 15th June 2013 at 02:59 PM. Reason: commercial link removed

  2. #2
    Not a Shoe Jimmytheboot's Avatar
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    Did you do the test with the blind filter described in the home barista thread? How many mls/minute came out?

  3. #3
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    Thanks for the reply Jimmytheboot, sorry to ask but just to confirm this test basically calls for a blinder filter (similar to when I backflush) in the portafilter, then running the brew (pumping water through grouphead) for 1 minute, measuring the output of the return hose.

    I thought this was a bad idea? Basically isn't this the same as running a backwash for too long?

    Sorry to be pedantic, just don't want to make things worse.

  4. #4
    Not a Shoe Jimmytheboot's Avatar
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    Yes thats the test, just dont do consecutive tests or more than 2 minutes and it will be ok, the pumps normal mode of operation is pumping against 9-12 bar, whether pulling a shot or backflushing.

    But to be safe you can do the test for less than a minute and calculate, start timing when drops start coming out of the hose.

  5. #5
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    I ran two one minute tests, seperated by a bit of time, I'm seeing a flow rate of 353 ml a min (both tests were within 5ml of each other). I graphed it up and the flow rate is constant.

    I'm guessing that this information from the other thread would be relevant? "No, your pressure is way low - caused by a OPV that is stuck partially open or as a real long shot, the OPV spring has broken. Replace the OPV internals and the copper sealing washer and you should be in good shape.".

    Appreciate the help.

  6. #6
    Not a Shoe Jimmytheboot's Avatar
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    It is high but doesnt borderline acceptable, Might just be grinding too fine for the dose used



    I would suggest borrowing/making a portafilter pressure gauge to know for sure, are you in Melb?

  7. #7
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    I am Melbourne

    Looking at your last comment, I dont think that I'm quite explaining the situation. My issue is that when I run a coffee shot, some liquid passes through the group head, however most is coming back into the water tank via the return water pipe (the one that runs out of the OPV).

    So I suspect my pump is ok, the only other thing I could consider is the OPV (or perhaps some kind of odd blockage in the grouphead/boiler path).

    Appreciate the help, thanks!

  8. #8
    Not a Shoe Jimmytheboot's Avatar
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    I understand your problem, but there will be water flowing out the tube during normal shots, looking at the above graph the pump will push ~250ml/min at 9 bar, so half would go through the puck and half out the opv.

    If the grind was too fine, 9 bar would not be able to push the 120ml/min out the puck so more comes out the opv. The numbers change depending on the opv setting, or if the seal perished or it was stuck open.

  9. #9
    Not a Shoe Jimmytheboot's Avatar
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    Quote Originally Posted by ozsmac View Post
    I am Melbourne
    You can borrow my portafilter gauge if you'd like, im in the western subs

  10. #10
    Senior Member CafeLotta's Avatar
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    If you look at the last part of the write up in this article there are some suggestions re: solenoid (3 way) valve diagnosis. Might be of some use.

    Commercial link removed

    Another link - http://www.1st-line.com/techsupport/...lvia_3way.html
    Last edited by Javaphile; 18th June 2013 at 02:21 PM. Reason: commercial link removed

  11. #11
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    Wow guys, I'm very thankful for your help and guidance. Jimmy, I think you have figured this out for me, I wasn't aware of water returning into via overflow......until I looked. Sadly this highlights another question, at times I'm getting hot water hissing back (during steaming) via the return pipe (this is what took me in this direction in the first place). So I suspect:

    a) My pump is doing ok
    b) My OPV is actually ok, a little high so I'll make some modification based on flow rates (I'm getting very constant test results, so will try without bothering you with borrowing your kit)
    c) my Auber PID is possibly over heating the boiler and creating pressure that needs to be vented out via the return

    Once again, thank you so much for the words of advice and for offering to loan me a test gauge (wow)!

  12. #12
    Not a Shoe Jimmytheboot's Avatar
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    Its unlikely the opv is opening when steaming, unless your opv is really set at 5 bar and boiler temps are reaching 160+.

    My guess is the water thats already passed the opv exit seal (while brewing) and thus is at atmospheric pressure is boiling, the opv is bolted directly to the boiler so it will be close in temperature. Theres only a few ml of space for water in the brass part of the exit, but it can become a much larger volume of steam.

    I will watch my exit tube next time im steaming and let you know what mine does.



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