Rocket HX losing steam pressure - Page 2

Beginner and pro baristas share tips and tricks.
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curmudgeon

Postby curmudgeon » Nov 02, 2016, 1:11 pm

homeburrero wrote:One way to check this would be to first trigger the normal autofill using the water wand, then run a series of long backflushes with a blank filter (and doing no steaming.) If your solenoid is leaking you will see a drop in boiler pressure, and may see water spurting out of the anti-vac valve if the boiler overfills to the top.


Another way would be to turn the pump on with no portafilter attached and capture the resulting water. This can be compared to a known value in mL/s for that pump setup (I've got a vibe pump so I don't know what that value is). If it's abnormally low, the solenoid could be leaking.

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Hooah

Postby Hooah » Nov 02, 2016, 1:18 pm

Thanks for the help! I'll try this tomorrow morning. One time towards the end of a pull while steaming the autofill kicked on and boiler pressure dropped to almost nothing.


homeburrero wrote:It is a little hard to tell whether or not a boiler fill is actually happening while trying to pull a shot. The pump is pulling from the reservoir irrespective, so the drop in reservoir level is not a reliable indication. You also may not see anything at the brew pressure gauge. You would, however, see a precipitous drop on the boiler pressure gauge.

If you have a good check valve and a bad autofill solenoid, it seems possible that you might have water filling the boiler every time you pull a shot. One way to check this would be to first trigger the normal autofill using the water wand, then run a series of long backflushes with a blank filter (and doing no steaming.) If your solenoid is leaking you will see a drop in boiler pressure, and may see water spurting out of the anti-vac valve if the boiler overfills to the top.

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homeburrero
Team HB

Postby homeburrero » Nov 02, 2016, 11:54 pm

Hooah wrote:One time towards the end of a pull while steaming the autofill kicked on and boiler pressure dropped to almost nothing.

Makes sense.

FWIW, I was curious about the autofill logic on this machine and did a little informal testing, and figured I should report what I found.

On my Rocket Giotto Evo V2 with the Rocket/Pro.El.inD controller, it appears that the autofill does not kick in while the brew lever is up. If I run a long 'brew' against a backflush filter and open the hot water wand, once the water in the boiler drops to where an autofill would normally occur, the controller switches off the element, but does not open the fill solenoid while the brew lever is up. After I drop the brew lever, then the autofill starts and the boiler pressure drops as the cool water comes in.

In normal operation, if you were to steam and brew when the boiler was low enough to call for an autofill during steaming/brewing, you would see normal brew pressure throughout the shot, but might notice a continued gradual drop in boiler pressure because of the heating element being shut off and not generating new steam. Then after dropping the brew lever you would notice the pump continuing with the autofill and the boiler pressure would dive, just as Hooah observed.
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h

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Hooah

Postby Hooah » Nov 03, 2016, 4:49 am

So after 1 hour warm up time I checked to see when the autofill kicks in by emptying water through the water wand. I measured the amount of water it took kick on auto fill 2 times, then put in a blank and ran 4- 30 second sessions. The first 2 sessions I did nothing but monitor the boiler pressure and watch the water level in the tank. The second 2 sessions I opened the water wand and let out double the amount of water it took to kick on the autofill in the beginning of the test.

Results: None of the pulls resulted in any drop of water level in the water tank during the pull. None of the pulls resulted in the boiler pressure to drop faster than normal. During the last 2 tests the autofill didn't kick on until the handle dropped at the end of the 30 second pull. No leaks found nor anything abnormal noticed. So in my opinion the solenoid is holding and autofill is working as it is supposed to.

The more I explore and test, the more I'm lead to think my pressure issue was my fault due to longer than normal pulls during steaming. I think the machine is optimised to steam a double cappuccino portion milk while pulling a 23-25 second double shot. Anything longer starts to degrade the machine's ability to stay on top of steam power. Does that make sense?

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homeburrero
Team HB

Postby homeburrero » Nov 03, 2016, 1:56 pm

Makes sense. In my machine, with the stock two-hole tip, I get great steam at first but after a while it is settling down to 0.6 bar of pressure. If the boiler level were to drop below the autofill probe during steaming+brewing it might go lower because of the controller turning off the heater circuit. If you're just steaming (brew lever closed) and the autofill kicks in your pressure will drop way low. Of course you can avoid that happening if you remember to trigger an autofill before you start steaming.

Another thing you might consider would be to change to a slower steam tip. It would give you less steam power initially, but the pressure won't drop while you're steaming. I'm now usually using a tip with two smaller than stock holes (mine is made for the Isomac, and requires an adapter to use on the Evoluzione wand) and I can leave it wide open and the pressure remains at 1 bar. It does take longer to texture the same amount of milk. I like slower tips because I find them easier to control for consistently fine microfoam - work more like the small single-hole tips I used to use on my Pavoni machines.
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h

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Hooah

Postby Hooah » Nov 05, 2016, 5:54 pm

Best steam/foam I ever had was from my LA Pavoni after I put on a single hole tip. I'll look for a single for the rocket, maybe that will make a difference.

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Hooah

Postby Hooah » replying to Hooah » Nov 06, 2016, 5:02 am

Tried the quick and cheap mod of plugging one of the steam holes in the original tip this morning before making my cappu and WOW!
So much better foam, exactly like my La Povoni made. Also boiler pressure stayed at 1 bar the entire time. Sure it took 15 seconds longer to steam but the results are well worth it! Now I almost don't want to sell the rocket :lol: