Rocket Giotto V3 Premium PID can't sustain steam pressure

[blazer78]

Hi all,

Just a quick question on steam pressure with the new V3. I've noticed on one video (https://www.youtube.com/watch?v=-AxPxuDn8d0 , not sure if they are using an older Giotto) that the steam pressure should not drop below 1 BAR.

However, on my machine, steam pressure starts at 1.1BAR (PID at stock 121 degrees C) and then drops to 0.7 BAR at the conclusion of steaming milk in a small 350ml motta milk pitcher. Steaming in a larger 600ml pitcher, the pressure starts at 1.1BAR and drops to around 0.5BAR near the end of the steaming process. I let the machine warm up for 45minutes, pull the shot and then steam milk. Is this drop in pressure normal?

Whilst I can get microfoam, it is never silky smooth. I presume this is because the machine runs out of grunt during the steaming process?

Your thoughts appreciated!

[wattgn]

It is normal. My Bezzera BZ40 with 3.4L boiler and two 1400W elements would drop in pressure during steaming. My current Wega Mini Nova Classic is identical in behaviour to your Giotto as the boiler and element size are the same.

If you want unlimited steam and little or no pressure drop you would need a 20L boiler.

You can try reducing the steam flow by using a different tip. I traded the five hole for a four hole tip. This helped. You can get even finer holed tips too which work better with small amounts of milk.

[gonzo89]

I hope someone else can chip in here, but with my previous machine ( Bezerra D Galatea) , and my current machines (R58, La Cimbali m21), my bar pressure never drops below 1 bar and if it does it's only for a quick few seconds as the element kicks it back up above 1 bar.
All the way to 0.5 or 0.7 isn't behavior I have dealt with before. Any other rocket v3 owners out there that can perhaps share their experiences?

[wattgn]

I hope someone else can chip in here, but with my previous machine ( Bezerra D Galatea) , and my current machines (R58, La Cimbali m21), my bar pressure never drops below 1 bar and if it does it's only for a quick few seconds as the element kicks it back up above 1 bar.
All the way to 0.5 or 0.7 isn't behavior I have dealt with before. Any other rocket v3 owners out there that can perhaps share their experiences?

It is simple physics. If I use a tip with two small holes then steam pressure will stay close to one bar. If I use high flow tips it is a different story. The tips that come with most machines are designed to froth quickly. The main issue is higher flow tips will froth very quickly which means you need to have good technique.

The element will kick in as the pressure drops but it takes time for the element to heat up and by the time it does, the job is done and the pressure has dropped also. A boiler is sized for the expected use. A 3.4L boiler with 2800W heating will do much more milk and quickly than a standard 2L boiler with a 1400W element.

Most home users will find a 2L boiler plenty.

[blazer78]

I hope someone else can chip in here, but with my previous machine ( Bezerra D Galatea) , and my current machines (R58, La Cimbali m21), my bar pressure never drops below 1 bar and if it does it's only for a quick few seconds as the element kicks it back up above 1 bar.
All the way to 0.5 or 0.7 isn't behavior I have dealt with before. Any other rocket v3 owners out there that can perhaps share their experiences?

The pressure is very stable at 1.1 when idling. However, even when purging for a second it will drop to 0.9 - 0.95BAR. Only takes a quick few seconds to recover back to 1.1 (from 0.5BAR) when not steaming .

[samuellaw178]

Doesn't sound normal to me.

Just throwing out some possibilities:

i) Most likely your vacuum breaker valve is sticking closed and accumulates false air pressure. Try purging the steam for 10 sec full blast and let it get back up to 1.1 bar, before doing the actual steaming. See if it improves.
ii) The autofill probe is set incorrectly - resulting a low water level.
iii) PID setting is incorrect - doesn't allow enough juice to the heater to sustain pressure when steaming.
iv) The steam tip is not optimized for the machine. Quite unlikely for a Rocket...

Except for option i. The others require more thoughts and probably a tech to look at it.

[wattgn]

It is normal.

This behaviour is what I've seen on every similar size machine.

Reality check. These are still small home machines made for relatively small amounts of milk and yes, you will see a substantial drop in steam pressure once you open the valve.

It isn't true to say you can go from .5 Bar to 1.1 Bar in a few seconds. For that to happen the water would have to heat 2L of water 10C or so almost instantaneously.

I experimented with my Wega Mini Nova Classic which has a 2.1 L boiler and 1400W element similar to the Giotto. If I do 15 seconds with my four hole tip, it goes down to 0.7 Bar and takes about 15 seconds to recover (as the element turns on as soon as the pressure drops). This would simulate heating a small amount of milk. Obviously if I use a fine tip then the pressure will stay high in the boiler due to the lower flow.

Same results as the OP with his Giotto, just needs to use a tip with lower flow and higher velocity if he wants to improve froth.

[samuellaw178]

If that is indeed the case, then it is the last option : iv) The steam tip is not optimized for the machine. I would be surprised it wasn't picked up by the vendors on this high end home machine that had received lots of improvisation over the years. In a market where most drinks end up being milk coffees, 350mL is not a big amount to ask for...

Big boiler is one thing, ideally you also want to keep the steam tip orifice matched to your element heat output. http://www.home-barista.com/levers/o...ps-t27312.html

Too much pressure drop is not good for microfoam texture as you need more power in the end for whipping/breaking the froths.


Addition: So I stand corrected. That much pressure drop seems normal for a Rocket Giotto.... https://www.youtube.com/watch?v=7fGUppjxx94

[TC]

My experience is that when buyers have difficulty with milk texture on a perfectly adequate machine, it's technique.

There's nothing wrong with the giotto wand or tip. The combo is in fact one of the best in the business.

The OP could set the PID to allow for a 1.2Bar max or thereabouts (approx 123 deg. C). in addition, a squirt from the steam valve before the shot is pulled will wake the PID and have it doing its thing to bring the element in.

Sometimes the tradie blames the tools...

[samuellaw178]

The OP is not blaming the tools here... He's asking if it's normal. So it is normal.

If the pressure drop is less it'd be an easier learning curve for beginners...not everyone starts out as a barista champion Didn't Rocket come with a set of steam tips (or are they extra accessories)?

[TC]

He's asking if it's normal. So it is normal....

Perhaps, or perhaps not. Flaky technique can amplify these types of issues. The best solution would be training and to have the machine checked to confirm that it's operating normally- which it should be if it was bench tested by the seller. In addition, the PID set temp increase as suggested will assist.

Didn't Rocket come with a set of steam tips (or are they extra accessories)?

They're accessories but not required IMHO. The Giotto already ships with the best tip option.

[wattgn]

The best tip is a matter of opinion. I had a five hole tip ship with my Wega. I swapped it for a four hole tip which is better. Honestly for the amounts of milk I typically do I would prefer even less flow but higher velocity.

I could have got by with the five hole tip but it froths so quickly, it takes more skill and timing than a slower tip where you have 30 - 40 seconds to leisurely froth the milk.

I suspect they like to give you a high flow tip so when reviewers test it, it looks good in terms of the time it takes to froth the milk.

[gonzo89]

I agree with the comments about using a tip that the user is more likely to get the hang of once they have the technique down. I hate the 4 hole steam tip on the r58. Yes it is faster but the texture isn't as good. Could be my inexperience with 4 hole tips I admit.
I always run a higher bar for steaming. Why bother with less power? It doesn't do anything better. As mentioned by wattgn, use a smaller hole tip perhaps for a little more control. And as Chris mentioned, purging the wand longer to get the PID to kick in is a way to get a more stable pressure throughout steaming. I give my r58 wand a very long purge or else I don't like the results.

[TC]

I hate the 4 hole steam tip on the r58..

It ships standard with a 2 hole gonzo89... Where did your 4 hole come from?

FWIW, about the only 4 hole I have ever used and liked (other than where necessary on commercials) is the stock LM style as found on the GS3/Linea mini/Slayer 1GR.

[gonzo89]

Well that answers the question Chris, it's certainly not a stock item ;-) I was trying to get used to a 4 hole but didn't like the results. All along I should have just stuck with the two stock steamtips as they work very well.

Well I'm glad to hear it's not just me who doesn't enjoy 4 hole steamtips in a domestic setting.