The Aurelia I used in this test did not heat up with flushing, but did cool off as I would have expected from a HX.

Thanks for the input. I would very much like to try out one of the temperature stable Aurelias someday.

I first came across the Aurelia at the 2005 SCAA. The heavy engineering had been already done, and the fine-tuning had begun. I was impressed enough to follow up with Nuova Simonelli,and based on the technical performance, we announced the Aurelia as our 2006 National Championship machine sponsor.

Since then, other countries have followed suit, but our Canadian baristas can be proud of the fact that we were the first to recognize the temperature stability of the Aurelia and the first to compete nationally on the new hx technology.

There was some controversy, as many competitors were only familiar with dual boiler machines. However, as baristas practised on the machines, they started to see and taste the engineering.

In a nutshell, if you try to use the Aurelia like a typical HX machine.. ( ie.. flush to cool), you will totally destabilize this machine.

The Aurelia is a no-flush machine. If you flush excessively, you will actually heat the head, raising the temperature of the brew water. Some baristas use this feature to their advantage to up-surf a degree or two. However for the purposes of the competition, we instructed our competitors to just do a “cleaning flush”.. ie. a quick blip of the pump, just to clean off any stray grounds on the group screen… just one second. The purpose of the flush is not for temperature regulation.

This is opposed to the usual temperature regulating flushes on La Marzoccos upon a long idle( up surf to compensate for a cooling grouphead ), and non-aurelia hx machines ( cooling flush to compensate for a heating group head/ thermosiphon).

Try this method the next time you are at the helm of the Aurelia, blip-flush for a second (RESIST THE URGE TO PURGE!!), and then brew your shot.

Fyi, if you excessively purge, and overheat the head, all you need to do is to switch groupheads, and by the time you’re done pulling your shot on the second group ( 90-100 seconds) , the first group will return to equillibrium.

Btw.. what is the pressurestat reading?

What does it mean to “optimize” this machine to get it to hold a constant temperature?

The WBC-spec machines are set up for 200*F, 9 bars, 1.0-ish bar steam boiler pressure, with selected baskets, steam-tips, etc. They aren’t “tweaked way out.” They’re simply optimized for WBC specs. Any Aurelia could be set up similarly.

The way the HX environment in the Aurelia achieves the temp stability that it does is frankly a lot to wrap my brain around, and it is dependent on many factors. Don’t mistake this fact with a mysterious souped-up WBC machine… it doesn’t exist. In fact, such a thing was against the rules of the WBC technical evaluation. It had to be a commercially available machine. No one-offs or special tweaks were allowed.

As mentioned, baskets and steam tips were spec’ed out for WBC. Otherwise, these are stock 3-group semi-auto machines.

1- I have a great deal of respect for the WBC and I do not wish to imply that they make back room deal, receive kick backs, or conduct their business without standards. I was surprised that what I saw in the Aurelias currently available did not seem consistent with what I would expect for a competition machine. (Competition spec machines will be in production after the Championship)

2- I believe that the WBC should get as much money in sponsorship deals as they can. These thing are way expensive, and we may not be having some or our regionals this year because of lack of sponsorship.

3- I would be thrilled to go head to head with any Barista on a heat exchange machine, any where, any time, any how (cage match if necessary).

The Aurelia is extemely stable. You only need flush or purge it for one to two seconds max. I know it is different from the LM. If you purge for too long you will bump up the temp as you experienced. Unlike standard hx machines running the group will not cool it down unless yourun it for a long time but that is totally misusing the machine. Greg Scace himself did the testing.