Breville Duo Temp channeling. Is pump failing?

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
JerryF50
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#1: Post by JerryF50 »

My 6 year old Breville Duo Temp Pro started pushing primarily foamy crema only when using the dual wall basket for the past month. I switched to single wall basket and now the espresso comes out fast with little extraction and very weak espresso. I'm suspicious this is a pump problem.

Does this sound correct?
Is the pump replaceable via "do it yourself"?

Here is a video with the portafilter off.

JerryF50 (original poster)
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#2: Post by JerryF50 (original poster) »

If the flow seems OK Is it possible the portafilter/handle can lose its ability to let the pressure build?

WWWired
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#3: Post by WWWired »

Hi JerryF50 :)
JerryF50 wrote: . . . I switched to single wall basket and now the espresso comes out fast with little extraction and very weak espresso. I'm suspicious this is a pump problem.
A single wall basket relies on the quality and level of grind of coffee to produce resistance. In a double wall basket, getting the 9 or so bar of resistance is less of a concern as the lower/outer wall of the basket has a single hole and acts as a restriction orifice. This limiting of flow by the single hole is designed to imitate the resistance produced through precise fine grinding and tamping of coffee powder in a portafilter. Resistance by the portafilter and coffee powder is necessary for espresso extractions by increasing resistance in the hydraulic pathway to the approximately 9 bar of pressure needed to achieve espresso range extractions of organics from the coffee powder. The upper/inner wall in a double wall basket is essentially the same as a single wall basket. With a single wall basket, increasing the fineness of the grind, having a good quality grinder that produces consistent particles sizes, combined with tamping/compressing the powder enough (but not too much), will increase the resistance in the hydraulic pathway to regulate pressure/resistance to the desirable 8 to 9 bar pressure range for better extraction of coffee organics. If the flow is "fast," it will likely be an indication resistance in the Brew Hydraulic Pathway (pump to grouphead) might be lower than desirable/designed and as needed for espresso extraction. Based on the provided description of "fast" and "very weak espresso," it sounds like a finer more consistent grind and perhaps increased pressure of tamping the powder in the single-wall basket would be worth considering :)

A Few Questions:
  1. What type of Grinder do you use?
  2. If using pre-gound coffee, is it espresso grind?
  3. Is there any tamping of the coffee in the portafilter being done?
If Above All Good, Then . . .
Without the portafilter in place (as you have in your video), run 60 seconds of water into a measuring cup that shows amounts (ounces or milliliters).

In a machine with a Solenoid (that has a limiting orifice of 1.3mm to 2.0mm depending on the model), about 600ml (about 20 ounces) of water per minute should be received from the grouphead, when no portafilter is in place, if everything is free of mineral scale build up and functioning properly. In a machine without a solenoid or any other orifices in the Brew Pathway, the amount of water the ULKA Model pumps will push out of a grouphead with no portafilter in place is expected to be 1000 to 1200 ml (cc's) of water (33 to 35 ounces) per minute.


Several experts on Home-Barista suggest 5000 extractions from a vibratory pump as the range where pump maintenance or full replacement could begin to be considered. Doing the math on a 6 year old espresso machine, one extraction per day for 6 years, works out to 365 days (most years) multiplied by six years to equal 2190 extractions. If you have two extractions per day that's just the one year amount (2190 extractions) times two for 4290 extractions. That is reaching the range of 5000 where a pump maintenance or full replacement might be considered according to some.

If you are getting 600 ml of water per minute, you may need only do some disassembly, cleaning, and maintenance of your ULKA pump. There is a tiny ball that can wear out (and can be purchased cheaply online), a few seals in the pump, and the plunger/piston can accumulate mineral scale buildup and need a Citric Acid bath for 5 minutes (2 Tbsp for 1 liter/quart luke-warm water). Citric Acid can usually be purchased in 2 pound/1Kg bags for $8-$10 from any brew or wine making supply shop, and has the consistency of salt more or less - it is the active ingredient in most descale solutions and is a weak acid, similar to acetic acid/vinegar, but just 3 times stronger than regular vinegar.

If you play poker, and are familiar with the concept of "burn the first card" during a deal . . . in this case when measuring how much water is being produced by your pump/hydraulic-pathway-resistance, permit the pump run for the first 2 or 3 seconds of water from your open group head and then start collecting the water and timing the 60 seconds. The volume you receive in 60 seconds will reveal several things. The health of your pump and more importantly the water resistance present in your Brew Hydraulic Pathway.

If you grind your own coffee, It is possible as well that your grinder (in a similar length of time of 6 years) is experiencing wear on the burrs and may not be producing as good a grind as when you first began and are now noticing a difference. Perhaps visit a local roastery or good coffee shop that will grind beans and purchase 100 grams of beans and have it professionally ground in their high-end grinders to espresso level grind. Try that out (within as short a period of time as possible after the grinding) to see if you get better extraction :)

Just some initial ideas. After you indicate your volume of water received in 60 seconds, the next steps should be revealed (including any component replacement method as needed). A photo of the exact model number will assist greatly as there are some variations depending on year of manufacture.

JerryF50 (original poster)
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#4: Post by JerryF50 (original poster) »

WWWired,
Thank you so much for your comprehensive and excellent discussion.
I use a Kitchen Aid Burr Grinder that is over 10 years old. When the problems with extraction occurred I adjusted the blades and I believe it is producing a very good grind (see attached picture with comparison to fine granulated vs Turbinado cane sugar). The grind is smaller than the Turbinado but larger than fine granulated sugar and appears to be very uniform. Yes I tamp always.



The output of water without the portafilter is only 12 oz or 350 cc in a minute. This Breville model shuts off after a minute on its own. This output seems to be quite low if I use your graph. Living in Western Washington we are fortunate to have relatively soft water so this is very suggestive of a pump issue and not scale build-up.

I assume the replacement pump is as here on Amazon:
https://www.amazon.com/gp/product/B077ZRP3GD/

Some models have a brass vs plastic tube connection.

Do you agree this appears to be a pump issue?
Do you have a preference in pumps?

Thanks again.

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HB
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#5: Post by HB »

JerryF50 wrote:I use a Kitchen Aid Burr Grinder that is over 10 years old... The grind is smaller than the Turbinado but larger than fine granulated sugar and appears to be very uniform... Do you agree this appears to be a pump issue?
Photos can be deceiving, but at first blush, that looks way, way too coarse for a non-pressurized ("single wall") portafilter. The audio is awful, but Newbie Introduction to Espresso - Grinders explains how to dial in a grinder by feel (not look).
HB wrote:For what it's worth, I did photograph the coffee samples:


Left to right: Finer, on target, coarser


Guess which is finer? Answer: It's a lot easier to feel than see
If you hang around this site, you're going to hear this again and again: It's all about the grinder. While I don't have firsthand experience with it, I'm betting a 10 year old KitchenAid grinder is your weakest link, closely followed by the age of the coffee.

It's possible the pump is failing or there's blockage. You can use a blind portafilter to check if it's pressurizes to 9 bar. If it does, then next up is addressing the flow rate. Based on the video and six years of use, I'd bet on blockage by scale or coffee gunk before the pump failing.
Dan Kehn

WWWired
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#6: Post by WWWired »

HB wrote: . . . It's possible the pump is failing or there's blockage. You can use a blind portafilter to check if it's pressurizes to 9 bar. If it does, then next up is addressing the flow rate. Based on the video and six years of use, I'd bet on blockage by scale or coffee gunk before the pump failing.
Brilliant insights by Dan Kehn as always :) Taking the shower screen off and checking it for "coffee gunk" as mentioned is a cheap and easy way to assess the state of any coffee organics build-ups like that.

As the post's title also suggests channeling, Dan's identification of buildups of coffee gunk come into to focus for sure. Before buying a pump, have a look at your shower screen . . . here's a picture . . .

JerryF50 (original poster)
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#7: Post by JerryF50 (original poster) »

Thanks for that suggestion, but I had already unscrewed the sceen and it was almost perfectly clean, so that is out.

Pumps are relatively inexpensive (compared to a new espresso machine!) so if I disassemble the Breville why wouldn't I just replace the pump? 12 oz in a minute is certainly on the low side.

I can set the grinder to even a finer grade as when resetting the blades I thought made the grain to fine, but I can reset.

Should I aim for as fine a grade as the granulated sugar?

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HB
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#8: Post by HB »

JerryF50 wrote:...why wouldn't I just replace the pump?
You could do that, though you're doing so based on a flow rate assumption that may not be true. That flow rate is for unimpeded flow; lots of espresso machines have gicleur (jet) restrictors which affects the flow rate. I'd start with verifying it pressurizes to 9 bar against a blind filter.

Even if you replace the pump, I am betting that will only expose the next weakest links in the chain (grinder and coffee freshness).
JerryF50 wrote:Should I aim for as fine a grade as the granulated sugar?
The video I mentioned earlier explains all this, but for the TL;DW crowd, it's finer than that - about the coarseness of white pepper. The problem with entry level grinders like yours, especially ones with 10 year old burrs, isn't that they don't grind fine enough. The problem is too much dust/fines, resulting in uneven extraction on one edge of the knife's edge and gushing on the other. Your grinder is perfectly serviceable for a pressurized portafilter; for a non-pressurized portafilter, it's nearly certain to be a frustrating experience.
Dan Kehn

WWWired
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Joined: 5 years ago

#9: Post by WWWired »

Agree 100% with HB's fantastic approach to this issue :)

Also Worth Trying:
With the Shower Screen removed, run water through the group head watching carefully (film for later reference if possible, and perhaps even post here if you'd like as well to assist future troubleshooters ;) ) . . . try to assess how the water is flowing through what Breville might call the "Inner Shower Screen" (and can also get clogged up) and might look something like this:


If you still want to consider the pump as a source for adding this issue, you can check your pump for issues fairly easily . . . here's a great video by a YouTuber by the name of Milen (NOTE: I put the >> wrong video << in originally and HB caught it thankfully (don't do what's in the linked "wrong video" as HB notes in the next post!) . . . have edited the post and put the correct one in now ;) ) . . .

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HB
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#10: Post by HB »

That's a cool video! Right until it shows him testing it with a loose electrical wire (!!?) right above to a well-grounded sink of water. What could go wrong? :shock:

Anyway, here's a helpful diagram:

Image
From Repairing a ULKA vibratory pump
Dan Kehn