In the never ending quest for better espresso (or latte), I decided to see for myself if the competition shower screens that some people have tried on various espresso machines actually provides better espresso on the Breville Dual Boiler. With the help of a lister here on H-B, I found just the right competition screen to fit my Breville Dual Boiler 920XL. This is a IMS competition shower screen: Precision IMS 51.5mm Group Head Screen - Non-welded - 200 micron - C_32 sold by Espresso Parts for around $30.00. A look at the two screens is attached. There is beauty in the comp screen...but will it provide better tasting espresso??
My experiment will be conducted in three blocks (water flow, extraction, taste) to provide anyone with the desire to perform this mod on their BDB a heads-up on what they might expect from a modest $30 upgrade. Let's face it, that's cheap as far as upgrades go...if it provides an improvement in the cup. So I have just completed the first block of testing. This was to determine if the competition screen changes the flow of water in any way versus the Breville oem screen. For this, I weighed the amount of water passing through the screens in a total of 30 seconds (including a 15 sec. preinfusion phase set to 55% power), some call this the water debit. Of course, without the pf attached, there is no back pressure, but the rate of fluid flow is significantly diminished during the preinfusion phase as controlled by the BDB pump. Below are the results from this experiment. Results that pcrussel50 would logically agree with.

OEM Breville Screen
15 sec. pre-infusion --- 53.2 sec. +/- 1.5 sec. (212g/min. @ 2-3 bars)
After 30 seconds (15s preinf. + 15s full pump) --- 166.2g +/- 3.7g (452g/min. @ 9 bars)

IMS Competition Screen
15 sec. pre-infusion --- 53.4 sec. +/- 1.1 sec. (214g/min. @ 2-3 bars)
After 30 seconds (15s preinf. + 15s full pump) --- 164.0g +/- 1.2g (444g/min. @ 9 bars)

n = 5 test per screen





Experiment Summary...No significant difference in water flow using the IMS competition shower screen versus OEM Breville shower screen. That is probably a good thing. Now if the water flow is more evenly distributed over and into the puck, then we have a good possibility that "soaking" each and every particle might take place, maximizing extraction yield. Plus, using higher levels of pre-infusion should make things even better for improved saturation.



Extraction and taste results to follow...

I look forward to your other testing! I've always pondered the idea of upgrading the shower screen for my BDB, but honestly there isn't a lot of information out there. I feel like the stock shower screen does a pretty poor job of distributing the water (unless it's absolutely spotless), so it will be interesting to see if the IMS screen will do better or of the Breville Dispersion block is more of the issue.

The lack of information on using a competition shower screen on the BDB is actually why I decided to post all this. Just want to be whatever help I can be to the BDB community. Nick, as for your comment about the dispersion block, your suspicion about its negative impact on water dispersion could be well founded. I have noticed hairline cracks around each hole and around the center hole. Not sure how many of us take the time periodically to unscrew the metal shower screen and pull out the dispersion block for cleaning and inspection. Fortunately, they are easy to purchase and cheap at around $3.00. It's just part of my monthly maintenance routine. I have two new replacement blocks, so I'm planning to replace the original, which is 2+ years old, with a new one next month.

Using IMS Competition Shower Screen on Breville Dual Boiler 920XL

Let's Talk Extraction and Taste:

So on to the extraction and taste part of the study. What can we expect from this modest $30 upgrade. Like I said before, this is an inexpensive mod as far as upgrades go... if it provides an improvement in the cup. So with the first phase of the study behind us (detailed in the beginning of the thread), let's discuss extraction and taste. For this part of the evaluation, I chose two coffees; Kaldi's -- Espresso 700 Blend (roasted medium), and Fieldstone -- Kenya AA (roasted med-dark). A total of 8 double shots were evaluated for each coffee using both screens. The experiment was spread out over a two week period, as to not over caffeinate myself. All shots were performed at 201F, using an 18g VST basket. The Espresso 700 included a 15 sec. pre-infusion phase set to 55% power, and the Kenya AA included a 10 sec. pre-infusion phase set to the same 55% power. The "time" in the results below includes the pre-infusion phase. Below are the results from this experiment.

Kaldi's Espresso 700 -- (target: 18g in / 36g out / 30 sec.)

OEM Breville Screen

In: 18.1g +/- 0.1g
Out: 36.0g +/- 0.8g
Time: 30.5 sec +/- 1.5 sec

IMS Competition Screen

In: 18.0g +/- 0.1g
Out: 37.0g +/- 1.4g
Time: 31.0 sec +/- 2.7 sec

Fieldstone Kenya AA -- (target: 17g in / 34g out / 28 sec.)

OEM Breville Screen

In: 17.2g +/- 0.1g
Out: 34.3g +/- 0.5g
Time: 27.3 sec +/- 1.8 sec

IMS Competition Screen

In: 17.1g +/- 0.1g
Out: 35.0g +/- 0.6g
Time: 25.6 sec +/- 2.4 sec


Study Summary...

1) With respect to extraction, no significant difference was observed in either shot time or output using the IMS competition shower screen versus OEM Breville shower screen. This effect was observed for both coffees utilized in this study.

2) With respect to taste, which is subjective, I would say that flavor in the cup was better, and I noticed this for both coffees. It appears, by my unprofessional palette, that the depth of flavor was manifest by a more distinct layering of individual flavors (eg, from fruit to cocoa, or sweet to bitter) and was more pronounced.

Side Notes: Below are my personal observations without any scientific proof.

1) No noticeable change in pucks sticking to the IMS screen after the shot has been pulled (occasionally happens). No better, but not worse. Maybe this was due to the fact that my IMS screen was not nano coated which should help this phenomenon.

2) It appears that the IMS screen stays cleaner after each shot (note...I perform a 2 second flush after each shot), so my observation is based on this "mini" flush. The backside of the screen was cleaner as well (see photo), this after 40 double shots (note: I perform a routine clean water flush after my last shot of the day). I suppose a nano coated screen might perform even better.

BOTTOM LINE: With no downside in switching to the IMS competition screen that I can detect, and only a huge upside for enhanced flavor in the cup, the IMS competition screen is now a permanent fixture on my BDB. I hope this helps those who have wondered about using a competition screen on their Breville Dual Boiler.
Comments and questions are welcome.

post deleted...

With no portafilter locked in how does the flow over the screen appear on the IMS vs the stock? Does it seem to be helping with water distribution?

It appeared to me that the droplets were larger in size, almost bubble shaped.

Thanks! So what one would expect from an IMS screen. Thanks for taking the time to do a write-up!

Nick,
One thing that I also noticed is that it seems that the water flow from the IMS screen disturbs the puck less...this is probably a great thing to minimize channeling. Here is a pic of one of my spent pucks after a shot. Notice the smooth surface with the usual shower screen marks. A lot of my pucks looked like worms crawled around the surface when using the Breville screen.

*sigh* wrote:...or if the Breville Dispersion block is more of the issue.

Nick,

Your comment about the dispersion block may be well founded. Here is a pic of my dispersion block after 2+ years. Note the cracks/fissures around the holes and especially around the center hole. If these continue to get larger over time it could change the flow of water and effect flow through the puck. Fortunately, they are readily available and cheap at around $3.00.