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Thread: Breville Barista Express 870XL Back Flush Problem

  1. #1
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    Breville Barista Express 870XL Back Flush Problem

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

    I brought a Breville Barista Express last week and have run 500g of coffee through the machine in this time (far more than normal because I wanted to dial in the machine!).

    I know the user manual doesn't say to backflush with water regularly, instead to do the chemical back-flush when instructed to do so by the light, but I want to keep my machine as clean as possible.

    With all this said, I have seen a number of Youtube videos where, when they back-flush this machine, the pressure gauge needle only goes to the middle of the espresso extraction range and they get a pot full of dirty water through the portafilter at the end.

    When I did my backflush, the needle shot right up to the max pressure the machine could show and throughout the whole process no water came through the portafilter!

    The only variable different is that I didn't add cleaning solution and they did on Youtube? I did push the plastic backflush disk in snugly into the single basket which I guess is right? The manual doesn't say either way! Maybe it should just be gently placed in the filterbasket?

    Please help, because it doesnt seem good to force the machine to go right up to such high pressure repeatidly!

    Any advice or your help would be hugely appreciated,

    Warm regards,

    Tom.

  2. #2
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    Yes that's definitely not right. It's possible you have accidentally gotten a backflush disc from a Dual Boiler machine which has no relief hole in it.

    Check the disc, does it have a small hole in the middle? If it does, make sure it's clear. If it doesn't, it's the wrong disc and you need the right one.

    You won't technically damage the machine with a completely blind disc as the pump does have a safety valve on it that will open under high pressure. Wouldn't recommend it long term though.

    If you are mainly going to be backflushing manually, you can keep going as is but just stop the water before you hit the peak pressure. This will still cycle the cleaner through but doesn't put the pump under too much strain.

  3. #3
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    Thanks for the response! There is no hole in the middle of the disk, but it seems quite unlikely they would have mixed up disks like that. Could it be a change they have implemented over the years going from a hole to no hole?

    I won't be backflushing manually, because the machine has an automatic backflush routine.

    I'm interested to know if anyone else has this model and brought fairly recently to see if their disk has a hole in it?

    Thanks again, it's much appreciated.

  4. #4
    Senior Member level3ninja's Avatar
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    Call Breville and ask them if it's still meant to have a hole or if it's changed to no hole, they'll know and if it's wrong can sort you out pretty quickly.

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    Will do and will report back in the morning! Thanks to you both for your time!

  6. #6
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    The newest machine I've seen was about 3 months old as of December last year and it doesn't have an over pressure valve, the pump system is the same as it's always been.

    I guess it's possible that they now ship with completely blind inserts and just rely on the safety valve to do its job but this seems unlikely.

  7. #7
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    Should have a hole they will send me one out today! I may just punch a hole in the current one and use it if my
    machine wants to be backflushed before the replacement arrives (I expect 2 weeks for delivery) Thanks again for the replies!
    level3ninja likes this.

  8. #8
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    Anther update I have to wait two weeks for the cleaning disk with a hole to arrive (i’m In WA) so I popped back to the store and asked if I could just do a straight swap with the cleaning disk from the machine that they have on display. The lady got the box and took out the cleaning disk and it too didn’t have a hole! Very strange!

  9. #9
    Senior Member level3ninja's Avatar
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    Must be a dodgy batch, either whoever makes the disc for Breville stuffed up or someone at the Breville plant put the wrong part in.

  10. #10
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    To quote Bender from Futurama:

    Bender: That'll take forever. What she oughta do is find a nice guy with two eyes, then poke one out.
    So, why not just find a large enough needle or a small drill-bit and poke a hole in the thing?

  11. #11
    Senior Member level3ninja's Avatar
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    Quote Originally Posted by inorog View Post
    So, why not just find a large enough needle or a small drill-bit and poke a hole in the thing?
    If you know the exact size it's meant to be to relieve just the right amount of pressure whilst leaving enough to get a good clean, sure.

  12. #12
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    Eh - it's a small hole - as long as it's not big enough to drive a truck through, I don't think it matters if it's 0.7mm or 0.8mm.

    From the pictures you can find about 54mm silicone disks - looks like the hole is about 1mm - start small and go up from there. Worst that can happen is you get a very very well cleaned machine.

    10130179-1.jpg
    A-hole is better than no-hole (never thought I'd say that)

  13. #13
    Senior Member Lyrebird's Avatar
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    Quote Originally Posted by inorog View Post
    Eh - it's a small hole - as long as it's not big enough to drive a truck through, I don't think it matters if it's 0.7mm or 0.8mm.
    Since flow through an orifice is a fourth power relationship, a small difference in diameter makes a huge difference in flow rate: increasing from 0.7 to 0.8 mm will increase flow rate at constant pressure by 70%.
    inorog likes this.

  14. #14
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    @Lyrebird

    Sir, I tip my hat to you! should've looked up my physics formulas before shooting the breeze!

  15. #15
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    Lots of replies, sorry I haven't checked in a little while! I sure could put a little hole in there, but as @Lyrebird said, without it being just right, there could still be too much or too little pressure. I plan to chemical backflush every two weeks, by the time the disk turns up, it would have been 3 so no big deal really

    Thanks again and super interesting on the hole diameter, apparently its tapered too! haha.



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