Preinfusion on La Marzocco GS3 MP with reservoir.

#1: Post by **caffeinezombie** » April 24th, 2014, 1:40 am

Hello all,

Recently had the chance to work with a GS3, but have a few questions regarding the pre-infusion process while drawing from the reservoir.

Is the pump supposed to be running during? I ask this because the amount of paddle travel that it allows me to move where the needle on the pressure gauge starts to drop to around 1-2 bars and the pump actually starts is something like 2mm. While this happens, water does start to trickle down, but at a pace of around 1-2drops of water per second(without a PF attached).

If this is indeed the preinfusion, is there anyway I can adjust the paddle such that I am allowed more travel before the pump kicks in?

Thanks!

#2: Post by **cannonfodder** » April 24th, 2014, 2:30 pm

It needs to be plumbed in for preinfusion. The drops you see are from thermal expansion of the liquid in the sealed hydraulics of the machine (residual pressure).

#3: Post by HB » April 24th, 2014, 3:44 pm

caffeinezombie wrote:Is the pump supposed to be running during?

Yes.

caffeinezombie wrote:If this is indeed the preinfusion, is there anyway I can adjust the paddle such that I am allowed more travel before the pump kicks in?

From the review:

HB wrote:As noted in the introduction, the La Marzocco GS/3 is available in two models, the AV and MP. The AV uses programmable 1-shot, 2-shot, or continuous pour buttons to actuate the brew cycle; preinfusion is provided by pressure from the steam boiler. The barista can set the duration of the preinfusion cycle before the full pump pressure begins and also the total shot volume. The MP, like the one in this review, uses a paddle to actuate and terminate the brew cycle. The MP's preinfusion is provided by line pressure if plumbed in or the steam boiler pressure if running from the reservoir, however the barista controls how long the preinfusion phase lasts by moving the paddle through three positions: off (full right), preinfusion (midway), and brew (full left).

In short, no, without water pressure from an external source, you cannot change the GS/3's preinfusion pressure. For the longer answer including an explanation of the "Strada mod", see the review background research.

April 24th, 2014, 10:55 pm

Thanks for the very comprehensive reply.

I had initially come across the thread you posted and had wondered if mine was simply a defective unit.

My initial understanding was that the pump didn't run(which I'm guessing would be the case if it was plumbed), and I barely had any play with getting the paddle to the pre-infusion position.