Just got my new Giotto Evo today after ten years with a Grimac. So far so good. I'm very impressed by its build quality and good looks.

It came from the factory with the boiler pressure set to 1.1 on the high end of the cycle and 0.9 on the low end. The green arc of the gauge is 1.0 to 1.4 with a redline of 1.5.

I read that Evo's come from the factory with pressure set at 1 bar but that 1.2 bar is preferable. So I upped the pressure to 1.2 on the high end and now the machine dips to 0.95 before the heater trips.

My questions are 1) are there other Evo users using this pressure setting? and 2) where in the cycle should I pull the shot?

The problem is if you wait til the machine peaks at 1.2 the water in the group is too hot (isn't it?) so I want to do a cooling flush. But when you do the cooling flush, the pressure backs down . . . .

The Evo will be much like many e61 HX machines. The current state of the boiler won't make a huge amount of difference (which is the same reason that PID on HX doesn't make as much difference as on a DB). The hx has a lot of thermal mass and flushing duration will probably make more difference than current state of the boiler. What the setting on the boiler will do is raise the resting temperature of the group and HX. And theoretically that's the beauty of HX machines. A minimal flush will always get you in the ball park and timing your flush appropriately after the end of the hot water dance will reliably get you where you want to be - the current status of the boiler within it's deadband being somewhat irrelevant. At least that's my current view of the situation. Someone posted the temperatures of the boiler at various pressures and it's not a big swing (can't recall the thread or the numbers right now)

Edit: found the temp data - it's in the HX temperature management article in the HOW-TOS section:

http://www.home-barista.com/hx-love.html

See particularly page two regarding boiler pressure settings.

Mike's right - ignore the steam boiler's heating cycle unless you're steaming milk. In that case, there's a small performance boost if you start steaming just before the pressurestat would click off.

Why on earth doesn't anyone put a needle valve on the thermosyphon of E61 machines? Or better yet, a temperature sensor controlled valve? Or just build a thermoblock integrated head like the bezzaras, only controlled to the exact brew temp you want and feed with water very close to ideal so it can be quickly switched in seconds!?!

All of these new Rocket machines have a 3.0 mm thermosyphon restrictor in the upper group pipe and their performance is very similar to the Vibiemme Domobar Hx model which has been extensively reviewed on this site.

Is the same true of the last generation (say, a year old) professional (pumped-in) model as well? It seems the new EVO has a balanced bypass valve that said, prior generation lacked. Any other "evo"lutions?

Thanks,

Tom.

Thanks for your post and reply. I was merely curious whether the new Evo had any significant differences, better said improvements over the professional. They seem roughly the same.

I based the assumption that the prior Giotto professional had a "standard" bypass valve on the information contained in following HB post:

Initial Set-Up of Rotary Pump Pressure

And, I concluded that the Evo had changed to a bypass valve based on 1st line's photo. As you can see from the link below, the Evo's valve screw differs from the professional's. Not only it is accessible from the bottom of the machine, but it also appears to include a "balanced" bypass screw.

http://www.1st-line.com/machines/comm_m.../index.htm

erics wrote:Based on my brief experience with one of these new Rocket machines, I would turn the boiler pressure down to 1.0 bar max reading, let the machine get acquainted with this new setting, flush a couple of ounces and brew.

A lot of machine parameters and operating procedures depend on whether you are:

a. enjoying a leisurely drink for yourself.
b. there is a line "out the door" with your neighbors dying to test the new machine owner's patience.
c. a cappy only person and thus do a lot of steaming.

All of these new Rocket machines have a 3.0 mm thermosyphon restrictor in the upper group pipe and their performance is very similar to the Vibiemme Domobar Hx model which has been extensively reviewed on this site.

Nice machine !

Eric -- did you say turn it down to 1 bar? It comes from the factory set to 1.1 at the top of the cycle and I bumped it to 1.2 per advice from a reviewer and others. What's your thinking there?