Having around 10 bars while brewing on La Marzocco GS/3 AV

September 29th, 2022, 5:15 am

Hello all,

I recently got a GS/3 AV. I have managed to do bleeding from group head, setting valve to have around 12 bars while heating etc.

So, the question is: I am seeing around 10-10.5 bars while getting espresso. I've tried changing dose to have less in basket (from 20gr to 19gr to 17gr) and also having coarser grind as well but it did not change. I have still have around 10-10.5 bars while getting an espresso shot. And I am seeing exactly 9 bars without portafilter while getting some water.

I initially thought it could be because of using VST basket, I also changed basket(repeated the same things, changing dose and grind size) to the ones comes from machine and it also did not make any change.

Is it something normal?

#2: Post by **Jeff** » September 29th, 2022, 8:05 am

Did you set the pump bypass value to 9 bar, or whatever value you desire for brewing?

September 29th, 2022, 8:30 am

No. It is stated in manual as:

The water pump is factory set at 9 bar pressure.

Do you think it is not set correctly in factory so that I have to change?

#4: Post by **Mihai Radu** » September 29th, 2022, 8:34 am

Yes, there is a screw on the pump after removing the left panel. This sets the max pressure after the pump. Mine ia at 7 bar giving around 6 in the puck but I only drink light roast.

September 29th, 2022, 8:36 am

I could not get a point, if it is the case should not I need to see same pressure in free water flow? What do you think?

#6: Post by HB » September 29th, 2022, 8:48 am

yasarcanyilmaz wrote:Do you think it is not set correctly in factory so that I have to change?

The pressure reading from the onboard gauge is not precisely the same as the actual puck pressure since there's a gicleur (orifice/jet) between the gauge's tee and the grouphead (IIRC, there's. ~0.5 bar drop). I would start at 9 bar on the gauge, following these instructions:

How to adjust brew pressure of rotary pump espresso machine?

Then adjust to taste.

#7: Post by **JRising** » September 29th, 2022, 9:42 am

yasarcanyilmaz wrote:No. It is stated in manual as:
The water pump is factory set at 9 bar pressure. 
Do you think it is not set correctly in factory so that I have to change?

Did you plumb it in and set your regulator higher than the factory's? If so, then yes, either adjust your pump or your regulator.

Or if the factory set the pump to 9 bar over inlet and you're feeding it water at three bar, you'll get (up to) 12 bar out of the pump.

But yes, it seems that everything is normal.

September 29th, 2022, 1:56 pm

I have not plumb it in. I am using it with water tank. I just started to play with pump pressure as described and now I have just started seeing ~9.5 bar in brew time. I need to modify again to see 9.

The point I still could not get is: If it has already set to 9 bars in factory, should not I expect to see 9 bar instead of 10,5 bar in brew time?

#9: Post by **JRising** » September 30th, 2022, 7:46 am

Yes, if it truly was factory set to 9 bar, then it would have arrived set to very close to 9 bar.