Commencing Final Dream Temperature Tests

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chas
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Commencing Final Dream Temperature Tests

Post by chas » Mon May 27, 2013 10:27 pm

Now that the Dream machines are in very good and stable configuration with the Dream 1.19 software it is time for one more final pass at temperature testing. I have long overstayed my loan of the 53mm Scace device I plan to complete testing as early as tomorrow and then return the device.

I had previously changed my PID settings to an equivalent value to what I use on my GS/3 and it works very well - much better than the Dream defaults. Today, I returned the PID settings to the default value P=500, I=150, D=10,000 and retested to see if the result was any different with the 1.19 SW compared to earlier versions. It wasn't. I still see a large overshoot, then the temperature settles a bit below the setpoint.

I am now testing some values more similar to the GS/3 settings to see if I can find a set of values that are even better. I'll let you know what I have finally settled on for my permanent settings.
Chas
LM GS/3 & LaSpaziale Dream v 1.23 (US 120V)
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Re: Commencing Final Dream Temperature Tests

Post by chas » Wed May 29, 2013 11:10 pm

After a lot of testing, the final values I'm sticking with are:
P=800
I=15
D=1000
Offset = 0F
Chas
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Re: Commencing Final Dream Temperature Tests

Post by goodboyr » Thu May 30, 2013 10:16 am

Chas: I assume this would be applicable to all Dream owners. Are there any consideration that we should be worried about before we try these?

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Re: Commencing Final Dream Temperature Tests

Post by chas » Thu May 30, 2013 10:55 am

If you haven't already done so:

1) Be sure the offset is set to 0F
2) Upgrade to SW v1.19
3) Change PID settings

One thing LaSpaz did in version 1.19 at my request is to implement the hold down button for fast scroll option to the Offset and PID settings. You will definitely need it especially when you have to change the D setting from 10,000 to 1,000. However, there seems to be a bug in it. If you hold down the button the value starts to increment or decrement by 1. After a few seconds it starts changing by 10s. However, within a few more seconds the increment/decrement stops and you have to take your finger off the button for 1-2 s and then press and start all over with the slow increment by 1. So while it is a still a lot faster than pressing the down arrow 9,000 times, it takes longer than it should due to this bug. Sometimes the machine would stop and beep at the same time. Other times it would stop and not beep. Let me know if the same thing happens when you try it. If so, I'll write it up and forward to CCS to add to the bug list for the next go around.
Chas
LM GS/3 & LaSpaziale Dream v 1.23 (US 120V)
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Re: Commencing Final Dream Temperature Tests

Post by goodboyr » Thu May 30, 2013 11:03 am

Another alternative is to directly edit the settings file and use the Write/Read feature. I will give that a try tonight.
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Re: Commencing Final Dream Temperature Tests

Post by chas » Thu May 30, 2013 11:12 am

That's works too. Just remember to correct your time and date after you do so since the original time and date from when you saved the file will get written back to the machine.
Chas
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Re: Commencing Final Dream Temperature Tests

Post by goodboyr » Thu May 30, 2013 6:47 pm

I confirm that the buttons behave the way you describe. It just seems to stop scrolling fairly randomly

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Re: Commencing Final Dream Temperature Tests

Post by goodboyr » Thu Jun 13, 2013 8:58 am

Question on how the displayed temperature changes during and after a warming pull with the new PID settings vs the old ones. With the new settings and a 10 second pull through an empty pf, with a setpoint of 199 F, the temperature drops to 189 during the pull, then after the pull rapidly recovers and then overshoots to 205 before settling back to setpoint. With original PID settings there was the same temperature drop during the pull, but there was little or no overshoot after. Chas: Is this what you see on yours? I'm just trying to confirm that the new PID settings are right for my machine.

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Re: Commencing Final Dream Temperature Tests

Post by goodboyr » Tue Jun 18, 2013 6:32 pm

Bump for my question above. Thxs.

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Re: Commencing Final Dream Temperature Tests

Post by chas » Wed Jun 19, 2013 12:01 pm

Without a Scace device or something very similar, it's very difficult to do any kind of apples to apples comparison.

First, the stability of the group boiler is dependent by design on having the flow rate be in the general range of no more than 2oz in 25sec. A little slower is probably OK but a faster flow rate will let cold water into the boiler faster than the boiler can heat it. So if you are just looking at the boiler temperature display and running water through the group without any kind of flow restrictor the temperature display is meaningless.

Frankly, when you reset the PID settings to the new ones I am using, the display temperature settings are also meaningless even when the flow rate is in the correct range. This is because the temperature probe is screwed into the top, rear of the boiler not all that far from where the cold water enters and the group where we want a specific water temperature to be stable is diagonally opposite from the temperature probe and about as far away as possible.

To try to get to the point, if you use the PID settings I am using and set the temp to 199F and the offset to 0F, you should get a pretty flat stable 199F at the group after 1-2 warm up flushes. The temperature may fluctuate around as to what the temperature probe says but it doesn't really matter what the water temperature is at that spot in the boiler, it matters only at the top of the coffee bed.

If you use the original PID settings, the display temperature will match more closely to the set temperature but won't necessarily correlate well to the actual temperature at the coffee and you may need a +2F offset.
Chas
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Re: Commencing Final Dream Temperature Tests

Post by goodboyr » Wed Jun 19, 2013 12:18 pm

Chas: Thanks for that explanation. I guess it all has to do with taste, and despite the wandering temp display, the shots are great with the new settings. One additional question: The overshoot on my temperature display results in a bigger than normal delay in the next shot if I am pulling back to back, because I am waiting till the display returns to setpoint after the overshoot. I think your explanation tells me that I don't need to wait. As long as the wavy line is off, it means the brew boiler has returned to short range PID control. When you did your scace tests, did you wait until the temperature display returned to the setpoint after the overshoot, or did you just wait until the wavy line went off?
Last edited by goodboyr on Wed Jun 19, 2013 12:42 pm, edited 1 time in total.
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Re: Commencing Final Dream Temperature Tests

Post by chas » Wed Jun 19, 2013 12:37 pm

Yes, I go by the wavy line turning off. That reminds me of one other test I want to make soon. I am wondering just how accurate the wavy line is. I also have a PID'd GS/3 and it just has two side-by-side black boxes that turn on and off when the steam and group boilers are cycling. On that machine every few seconds one or the other or both turns on just for a second or two indicating a frequent pulsing to keep the temperature right on target. This seems to me like the way a PID'd machine should work.

However, if I look at when the wavy line turns on and off on the Dream it is pretty much the exact same on-off pattern and times as the older generation of non-PID'd S1 machines. So what I want to do is connect an AC voltmeter across the boiler element on the Dream (or maybe even an oscilloscope if I need a faster response time) so I can see if the boiler's real on/off cycles at all match the wavy line.

Several SW versions ago there was a bug where if you set the Dream to the max offset the wavy line turned on and stayed on. However, I did not get any indication of expected overheating when it was in that condition so I connected an AC voltmeter and the voltage seemed to be pulsing like it does on the GS/3. I have not gotten back to recheck this with the newer SW versions, but I must!
Chas
LM GS/3 & LaSpaziale Dream v 1.23 (US 120V)
Mazzer Kony E, Customized Rocky
Hottop P/B

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