# Using The Steam Wand Control To Reduce Grace's Brew Pressure to 9Bar



## antinwales (Jan 16, 2021)

I posted on here a few weeks ago about how my Grace brews around 11bar, so I've made a video showing how I'm using the steam wand valve to reduce the pressure.
I'm genuinely curious to know what you think, and whether the rest of my workflow looks OK.
Video covers:
- Proof the OPV is set too high (and admission that its adjustment is too complex)
- Why this matters (err, channelling)
- How to do it
- Results using naked PF
- The terrible consequences of following Lelit's "grind coarser" advice (60g out in 18s)


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## Zorkin (Feb 5, 2021)

Nice video. 
If you are investigating channeling I'd suggest a bottomless pf as a minimum. 
It gives you immediate feedback on your prep etc

I found through usage with a very similar setup ( orange specialita and a Victoria ) that a good distribution and tamp is for me at least the key ( making sure the distributor is adjusted so it does not tamp , not too deep and not too shallow ) as is a good quality basket ( I use a VST 18 gr )

I switched off pre infusion as I find that on this setup it actually makes a negative impact.

Brewing at the preset pressure does not seem to result in channeling for a well prepared puck.

As for rattle, I added little plastic micro dots on both the underside of the tray and the carriers for the water tank cover. Cheap and cheerful and they do reduce rattles


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## antinwales (Jan 16, 2021)

Interesting reply @Zorkin, thanks

Yes, bottomless PF has been useful to show no channelling going on - go on then, I'll switch off pre-infusion for a few and use machine pressure for a few, although I'm as worried by effect of over-pressure on taste (over-extraction) than about channelling.

Agreed on upgrading basket, and my distribution is feeling good.

The funnel is great (though sadly no use to me) but can you tell me more about the "micro dots"?
I Google'd and found myself in some LSD sub-reddits.
I have never seen such a thing - could you post a link please? They could be just the thing!


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## Zorkin (Feb 5, 2021)

Hold off on the LSD and start with those.

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## El carajillo (Mar 16, 2013)

I would suggest you purchase a bottomless P/F, use WDT on the grounds to uniformly distribute and break up any clumps,make sure your tamp is level.

Forget fiddling with the steam wand valve. The 10/ 11 bar pressure is not way out for pulling a good shot.

Are you using freshly ground fresh coffee ? Try grinding finer and tamping more firmly.

As for tasting the difference between 9 and 10/11 bar forget it.

If you wish to change the pressure do a little more research.


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## DavecUK (Aug 6, 2013)

@antinwales Nice bit of video work. I echo what @El carajillo says about not getting too hung up about the pressure. Get the grind and prep right and it will extract just fine. My thoughts on what you're doing with the steam knob (especially as you need to close it pretty quick at the end of the shot).



You are passing a lot of extra water into the drip tray when you drop the pressure like that


The water is from the hot side, so all that extra water is going through a small boiler (the expansion valve rejects it before the boiler), the recovery time for a second coffee will be much more difficult, it may also overshoot.


The steam valve uses a Teflon pad...so It might well have a short life being opened and closed so often


You have to be careful not to create voids in the boiler with the valve open after the shot....fortunately, the boilers probably cooled down massively by the time the shot ends, so that's not so much of a risk.


The expansion valve on those isn't very adjustable, so there is the option of fitting a different one, that is small and neat, but can be adjusted easily and then left at 9 or 9.5 bar. I would think this is the optimum solution.


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## antinwales (Jan 16, 2021)

Thank you all for the replies.
Ive been doing this wand thing a few weeks now, so maybe it's worth me stopping for a few weeks to see what happens.
I do worry about the puck being smashed by 11bar of pressure, but I'll give it a go ...


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## DavecUK (Aug 6, 2013)

antinwales said:


> Thank you all for the replies.
> Ive been doing this wand thing a few weeks now, so maybe it's worth me stopping for a few weeks to see what happens.
> I do worry about the puck being smashed by 11bar of pressure, but I'll give it a go ...


 Where are you getting this "smashed" thing from?


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## 27852 (Nov 8, 2020)

Pressure isn't inherent to the machine, it is just describing the amount of resistance the puck is giving relative to the water flow from the group. The statement "pressure is too high" can only be the result of two things: 1) flow rate of the machine is excessive - you can gauge this by measuring water weight out over a set period of time. 2) the puck is providing too much resistance against the flow of water. Assuming the machine has been properly QC'd then it is more likely to be option 2.

It shouldn't be of concern unless you are experiencing channelling/fracturing of the puck. If that is happening then you should back off the grind. If it's tasting good then you don't need to worry about it. There isn't a special chemical reaction that turns ground coffee into manure when subjected to hot water and pressure in excess of 9bar.


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