Breville Dual Boiler - Correct Brew Pressure

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dimvos

#1: Post by dimvos »

Hello!
I am the owner of a Breville Dual Boiler and I would like to know what the pressure gauge should show while pulling a blind shot in order for the pressure at the brew head to be at 115 psi while pulling a shot with a Scace attached. I don't have access to a Scace device and I don't think that it would fit the machine anyway. I am just hoping that someone in this forum could answer my question.
Thanks!

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Jeff
Team HB

#2: Post by Jeff »

A rough guess is about a 1-bar drop between static pressure with a blind basket and in-basket pressure at classic extraction rates for many machines. I don't know where the BDB measures the pressure, but I would guess that it is before any restrictions in the group, like most other machines.

115 PSI is about 8 bar, so you'd probably want to be around 9 bar on the gauge to get close to 115 PSI.

Edit: See next post. If measuring in the brew chamber, you'd want to set around 8 bar for 115 PSI.

I would suggest testing the taste of the shots over a few days at each of a range of settings. There is nothing right or wrong about "9 bar at the pump". When I was trying this the first time, I found that I had preferences with a 1 or 2 bar change, but that 1/2 bar wasn't very clear of a difference.

luvmy40

#3: Post by luvmy40 »

dimvos wrote:Hello!
I am the owner of a Breville Dual Boiler and I would like to know what the pressure gauge should show while pulling a blind shot in order for the pressure at the brew head to be at 115 psi while pulling a shot with a Scace attached. I don't have access to a Scace device and I don't think that it would fit the machine anyway. I am just hoping that someone in this forum could answer my question.
Thanks!
The BDB pressure gauge shows the pressure at the brew chamber.

Scwheeler

#4: Post by Scwheeler »

I've been thinking of adjusting my OPV since I saw James Hoffman's video a few months ago. Most of my shots hit the limiter for first 10-15 seconds and this shows on the gauge as exactly 10PSI.

From speaking to others this seems to be the way most leave Breville so it seems intentional and within the ideal band shown on the gauge of 8-10PSI.

I understand ideally testing myself, however before I void my warranty I wondered if those who have tried it or anyone with a better understanding of pressure then me think this is too high and I may get better tasting shots at a bar or two lower?

BaristaBob

#5: Post by BaristaBob »

Scwheeler, I don't think you will void your warranty just by adjusting the OPV. This should be operator's choice. As for the "correct" extraction pressure, Jeff is right on here. The Italian standard, I believe, specifies 9 bar. However many have found that even declining pressure...down to 6 bar (eg. Decent, Slayer, etc) produce tasty shots too.
Changing the pressure at the OPV on the BDB is not hard, it's just a pain since you need to undo the discharge side tubing to make an adjustment, then reconnect and see what you have...repeat, and repeat. I would recommend that you purchase a replacement OPV before attempting this. A few people have broken the OPV since it's made from cheap plastic and over time the interior heat can make it extremely brittle.
Bob "hello darkness my old friend..I've come to drink you once again"

Scwheeler

#6: Post by Scwheeler »

Thanks Bob, that's a very sensible suggestion, I'll have a look into picking one up.