Pressure drop on Rocket Evoluzione during steaming

Need help with equipment usage or want to share your latest discovery?
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spiffdude
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Real Name: Marc André
Equipment: Rocket Cellini Evoluzione, Compak K10 PB
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Postby spiffdude » Sun Aug 14, 2011 8:42 pm

Hi guys, gals,

I've noticed a pressure drop on my Rocket Evoluzione when preparing steamed milk. Here are some details:

- machines turns on with a timer
- I hear the boiler working and minutes later the vacuum breaker seals up
- about 30-45 minutes later, i arrive and start the first shot. Machine is hot, pressure is cycling within 0.8-1.0 bar every few minutes, factory settings
- i flush and pull the first shot and start steaming some milk.
- i notice that the pressure in the boiler drops quickly (the autofill has not kicked-in), down past 0.6 bar while steaming 5-6 ounces of milk. Not enough to open the vacuum breaker but enough to slow my steaming considerably
- i shut the steam valve and the boiler rebounds within 50-60 seconds to 1.0 bar.
- i can then steam again but this time, i do not seem to run out of steam so fast. I can actually do another 6-12 ounces with no real problem.

I'm a bit at a loss to explain this issue. My first reaction was jammed vacuum breaker hence false pressure issue but since i can hear it sputter and close during warm up that not it. It also happens without the autofill working so it's not dumping cold water in the boiler.

Can it be that i'm running the pressure stat too low? Can some Rocket owners chime in? i recall reading posts of people trying different settings and coming back to the factory one. On the other hand, i read on Bellabarista's site that they change the setting to 1-1.2 bar before shipping to clients.

I'll try increasing the pstat but i figured i'd also ask around. Thanks for any feedback.
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erics
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Postby erics » Sun Aug 14, 2011 9:18 pm

The "factory default" setting I have seen and read about on Mr. Rocket (all of their models) is 1.10 bar max, i.e. you should not see the gage needle go past 1.10 bar.

My impression (from very briefly using one) is that these machines are very capable steamers at 1.10 bar and will "wake the neighbors" at 1.20 bar.

I sorta think your water level has crept up a touch due to a little corrosion on the probe.
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at erols dot com

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spiffdude
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Real Name: Marc André
Equipment: Rocket Cellini Evoluzione, Compak K10 PB
Location: Montreal, Canada

Postby spiffdude » Sun Aug 14, 2011 9:40 pm

thanks for the reply Eric, my machine never cycled over 1.1 bar so that is inline with your experience.

i may need to pull out the water level probe to confirm if it has corroded or has scale. i will find some time to do that and report back. Is there a chance i can re-install it wrong and affect the water level?

FYI for Rocket owners, here is where i had read a recommendation for the pstat at 1.2 bar. Experiment at your own risk :shock:

http://www.bellabarista.co.uk/coffeemachines/rocket-espresso-cellini-evoluzione-coffee-machine.asp

Open the "closer look" pdf file.
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erics
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Postby erics » Sun Aug 14, 2011 10:24 pm

Is there a chance i can re-install it wrong . . .

Well, yes, Marc, but it is slim to none - honest. Just note the vertical position of the connector before you apply the wrenches.

Here is a pic of the Quickmill Anita arrangement - yours will be SIMILAR.

Image

Item 2 is what is properly called a "gland nut" . As you tighten this fitting, you increase the squeeze that the teflon tube (item 3) applies to the probe. If you fully loosen the gland nut, you should be able to twist and pull the probe out of it's teflon sleeve - take it slow. On an older machine, this could inflict some damage to the teflon but on yours and mine - slim to none. Clean probe with some abrasive paper, rinse, and reinstall.
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at erols dot com

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spiffdude
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Equipment: Rocket Cellini Evoluzione, Compak K10 PB
Location: Montreal, Canada

Postby spiffdude » Mon Sep 12, 2011 7:25 pm

Well i finally got around to opening up my machine. I took out the level probe and found this (see pic). Does this qualify as a significant amount of oxidation or scale?

Anyway, i used some ultra fine sandpaper to shine it up and reinstalled everything. I did a quick startup and the machine came up temp. I also pulled some water and the refill reacted properly. Seems like i didn't muck up anything. 8)

I will report back on the steam results tomorrow when i fire things ups for the morning cappuccinos. Will let you know how it goes.

Image
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nixter
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Postby nixter » Wed Oct 19, 2011 12:18 pm

I am having a similar problem with my Rocket Giotto Evo. I just performed a descale a few weeks ago though. I'll have to check the probe in the next few days. How does the probe detect water height exactly?

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spiffdude
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Postby spiffdude » Wed Oct 19, 2011 8:20 pm

Well steaming it still a little disappointing even with the cleaned up probe. It just drops to 0.6-0.5 bar quickly. Now i'm not sure if it was doing this when it was new and i just didn't notice. :?

I wonder if the probe sits a little to high thus allowing an abnormally high level of water in the boiler. Might need to check with Rocket how i can verify the probe height.

Nixter, i think that when water touches the probe end, it grounds the signal and that is what is used to stop the pump from refilling further. The probe is really just a piece of metal connected to a wire.

If the probe end is covered in scale, then the water has to go up a little further until it touches bare metal. This would also lead to a higher than normal water level. Since i took out the probe and shined it up real good i can cross out that possibility. Since you descaled and took care to overfill the boiler i think that would also eliminate this venue.
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nixter
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Location: Vancouver
Interests: Bodybuilding, Nutrition, Espresso

Postby nixter » Wed Oct 19, 2011 8:27 pm

Yeah I would have thought the overfill would have taken care of that as well but who knows. I'll pull the probe and see. If it looks clean I'll shine it up anyways and see. If that does nothing I suppose I could try just inserting it a bit further. I'm pretty sure it did not behave this way when i got it.

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spiffdude
Posts: 303
Joined: Sun Sep 26, 2010 9:24 pm
Real Name: Marc André
Equipment: Rocket Cellini Evoluzione, Compak K10 PB
Location: Montreal, Canada

Postby spiffdude » Wed Oct 19, 2011 8:39 pm

Let me know how what you find out.

I might just try pushing the probe in a bit as well.

Cheers fellow Rocketeer :wink:
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User avatar
nixter
Posts: 748
Joined: Wed Apr 16, 2008 7:49 pm
Real Name: Nikolai
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Location: Vancouver
Interests: Bodybuilding, Nutrition, Espresso

Postby nixter » Wed Oct 19, 2011 8:57 pm

Yes, there needs to be more of us! I'm actually surprised there aren't more of us given that the new Rockets are easily the best looking HX's around. ;) That... and having excellent internals, great build quality and good pricing.