Bianca pressure

Penance

Had the Bianca around 2 months now and I have changed nothing from the settings it arrived with, just been enjoying using it.
The pressure at the moment i 11 bar at the group using a blind basket, should i drop that down to 9 bar?
Ive yet to get any really wow shots which is likely down to me, i get a lot of sour shots, some very nice with milk but a little sour a a straight shot. Could the pressure be a cause of this?

MediumRoastSteam

Penance some very nice with milk but a little sour a a straight shot

Increase your temperature. What’s the current temp?

Are you waiting for the machine to stabilise after initial warm up? How long do you wait?

Are you using a wam portafilter?

Cuprajake

yeah you can drop it, i did on mine, iirc it shows around 8 bar at the pump.

do it when the machine is cold

Penance

Cuprajake Thanks.
Do you think that will go some way to improving shots?

Inspector

Cuprajake I thought adjusting opv should be done when machine is up to temp.

Cuprajake

if you’re not using the paddle then yes,

obs temp, grind, dose and bean will change this too

Penance

Not used the paddle yet, figured i should get to know the machine in basic form before exploring that.
Ive played with everything else, for my most common bean (Dark Peak) I am dong 18/36 at around 30 seconds, temp is 93c.
Ive been trying a lot of other beans but only small batches so not the best as a benchmark.

Penance

MediumRoastSteam Current temp is 93c, machine is on for around an hour before i make first shot, PF is always left attached so is warm.

MediumRoastSteam

Inspector I thought adjusting opv should be done when machine is up to temp.

you don’t adjust the expansion valve (aka: OPV). You adjust the pump bypass (It’s a machine equipped with a rotary pump).

Inspector

MediumRoastSteam Didnt know the difference, thanks.

MediumRoastSteam

@Penance -

Cuprajake

pumps adjusted under the machine

Petre

11 bars rarely is a good pressure. Most of the time 6-9 bar is the sweet spot. Experiment with all these to see what you like. For example, using your paddle you can reproduce profiles like this https://www.scottrao.com/blog/2021/5/18/best-practice-espresso-profile?format=amp

Penance

Ive tried the paddle just now, think i need to give it more time but i cant get it to cap the pressure, just slow down the ramp time.

MediumRoastSteam

Penance but i cant get it to cap the pressure, just slow down the ramp time.

It’s a flow control valve, not a pressure profiling control. In other words, it will restrict the volume of water entering the group (and pressure will build up, slower, providing the inlet rate (into the group) is greater than the outlet rate (out of the group and into the porta filter). So your experience is correct.

Cuprajake

a very good go to is:

7pm for 10s

fully open for 10s

slowly close to around 7pm for your 30-40g shot

pressure 9 bar though

Penance

Cuprajake I’ll give that a go over the weekend. I think i may need to adjust the paddle first as it doesnt seem to open until 9pm ish

Cuprajake

MediumRoastSteam

Cuprajake - Yeah, I saw that video too. The one I posted although the title is misleading, it shows and explains the pressure in the circuit and how you adjust the expansion valve (OPV) inline with the pump bypass valve.

In other words, if the pressure of the pump (visible in the manometer) is greater than the what’s set for the expansion valve, water will trickle through the valve at the front of the machine.

Del_UK

Penance

Mine needed a bit of tweaking to get it to how I find it most useful, but now I’ve got the hang of it, I use it for every shot. Even on straight 9bar shots I emulate the e61 by dropping a second or two once pressure starts. @DavecUK has a fantastic video showing some different shot profiles. I’m a big fan of lighter roasts and the definitely-not-exactly-like-a-Slayer method to be great for said brews.

Penance

MediumRoastSteam thanks for the explanation, makes sense now.

DavecUK

MediumRoastSteam In other words, if the pressure of the pump (visible in the manometer) is greater than the what’s set for the expansion valve, water will trickle through the valve at the front of the machine.

Just to be clear, the expansion valve should be set to have just a trickle at 11 bar, then the pump lowered to 10 bar and then check that the expansion valve isn’t letting by.