Weird flow on Aurelia II

Q&A
1

I recently got a refurbed 2013 Aurelia II for my shop.

It ran pretty well but the group dripped between shots and the flow rate was pretty intense. One of the Simonelli techs told me to disable the soft infusion system to stop the group dripping and to fit 0.5mm gicleurs to sort the flow issue.

Disabling the SIS fixed the group, but the smaller restrictors have made the flow rate a bit weird; the group ‘sneezes’ sometimes, almost like it isn’t getting enough flow:

This affects the volumetrics and it throws up short shots quite often.

With the restrictor, I get around 220g of water in 30 secs which is in the ballpark. Without it, it’s more like 380g but with more consistent volumetrics.

I had a tech out to check the machine - there’s no scale in the hx pipes and he went over a few other thing he thought it might be but couldn’t work out what was causing it. We took the 0.5mm restrictors out and got more constant flow.

I’m guessing with this the lesser of two evils would be the bigger restrictors and the constant flow rate? The smaller restrictors have water debit that’s more inline with modern thinking but the unpredictable flow and wasted shots sort of negate the benefit.

2

So having spent the morning unpacking some ideas in this thread on flow rate, i’m going to try going back up to a higher pump pressure and see if that helps: ‘In the end it´s not the pressure but the water moving through the puck that extracts the coffee. What you want is a reasonable flow rate and an adequate grind size’.