I checked brew pressure on my Appartamento based on the "overly high pressure" claims I've seen around. Mine was running right at 9 bars.

The only "Must Have" as far as I'm concerned is a grouphead thermometer.

gania13 wrote:Hi everyone
I recently replaced my Elektra micro casa a leva with Rocket Appartamento and have a couple of questions:

1. I've seen online that the factory setting for brew pressure is approx 13-14 bar, what's the logic behind that? I'm sure Rocket know what they're doing, so why some people say that you should adjust the OPV to 9 bar?

The problem is you end up with 12-13 bars at the group in operation, for some reason. I have no idea why they set it that high, but they shouldn't.

2. I have a Ceado E37s, does it make sense that I need to grind finer for the rocket than I did for the Elektra? I always thought that lever machines are much more finicky with grind size.

If anything, manual levers are more forgiving. Anyway, the E61 group uses a wider basket than the Elektra lever group, so for the same dose you'll need to grind finer because the puck is thinner. Plus with the Rocket running at a high pressure, you'll have to grind finer.

3. Are there any "must have" upgrades I should do to optimize the experience? I'm new to E61.

Given the Appartamento's total lack of brew temperature control (just a pressurestat on the steam boiler), a group head thermometer is almost a must if you want to have any actual ease of repetition.

gania13 wrote:1. I've seen online that the factory setting for brew pressure is approx 13-14 bar, what's the logic behind that? I'm sure Rocket know what they're doing, so why some people say that you should adjust the expansion valve OPV to 9 bar?

That has been fairly common for over 20 years, and reportedly was advised for machines that might sometimes be used with ESE pods. When using a vibe pump with the right dose and grind of coffee, the pressure at the puck would not go that high. On the appartamento, I think there is some benefit to setting the expansion valve (OPV) down to 9.5 or 10 bar on a blank portafilter, so that even if you pull a nearly choked shot the puck pressure would not go much above 9 bar. (When I reduced the expansion valve setting on my old vibe pump ECM Giotto from 12 bar to 10 bar, I *think* that it helped make my tight ristretto shots more consistent with less appearance of channeling.)

On a rotary pump machine, you set the pump bypass to 9 or 10 bar, and leave the expansion valve up around 12 bar, just to bleed off pressure from the closed brew circuit due to water expanding when heated.