Our Valued Sponsor
OpinionsConsumer ReviewsGuides and How TosCoffeeGeek ReviewsResourcesForums
Espresso: Espresso Mods and Restorations
Computer controlled temp and flow profiling
Commercial Equipment
Nuova Simonelli, La Marzocco, Rancilio. Nationwide installation. Instant financing options.
www.seattlecoffeegear.com
 
Not Logged in: Log In to Postlog in
New Topics updated topics   New Posts new posts   Unanswered Posts new unanswered  
Search Discussion Board search   Discussion Board FAQ faq   Signup sign up  
Discussions > Espresso > Espresso Mods > Computer...  
view previous topic | view next topic | view all topics
showing page 5 of 9 first page | last page previous page | next page
Author Messages
jonr
Senior Member


Joined: 25 Jun 2013
Posts: 258
Location: Americas
Expertise: I like coffee
Posted Tue Aug 27, 2013, 10:39am
Subject: The 3 second bump
 

Independent of any heater control that I do, I consistently see a 3 second upward bump at the beginning of the temperature profiles.   Then it flattens out and I can control the slope or shape.  Many graphs from others with fast responding temperature measurements show the same thing.

Any thoughts on why this occurs?   Maybe a thin layer of extra hot water at the top of the boiler?  Maybe using a cold portafilter would knock it down.  Or a 1 second flush prior to brew.  Or lowering the intake tube in the boiler slightly.

jonr: graph.png
(Click for larger image)
back to top
 View Profile Link to this post
D4F
Senior Member


Joined: 15 Mar 2012
Posts: 1,878
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Preciso
Posted Tue Aug 27, 2013, 11:49am
Subject: Re: The 3 second bump
 

Not quite sure I understand what you did.  You mentioned a thermobasket with RTD sensor but I did not see further explanation or picture.  Puck simulator or real brew?  What is plotted?  What is going on in the first several seconds, about 8 - 10 seconds.

If you turn off all controls, added heat and pre-brew bump, and just hit brew using brew light as a guide do you get the same?

Interesting Auber plot with Scace.  You may be suggesting that Scace is too slow, or no similar peak in that study?

Click Here (www.afonic.org)

I am just trying to understand what you did and what may be inherent in the machine.

 
D4F also at
http://www.gaggiausersgroup.com/
back to top
 View Profile Link to this post
jonr
Senior Member


Joined: 25 Jun 2013
Posts: 258
Location: Americas
Expertise: I like coffee
Posted Tue Aug 27, 2013, 12:03pm
Subject: Re: The 3 second bump
 

Yes, thermofilter, A/D results from a very small RTD just above the coffee, actual brew with coffee including 10 seconds of pre-brew time in the graph.  Happens even without any extra heat (maybe I should try without even the baseline PID heat).  The upward drift from 0-10s is the freshly loaded coffee warming up.  This particular run was adding some heat later in the brew (which is why it didn't fall off as much as the Classic usually does).

My guess is that any graph that shows temp taking more than 2 seconds to fully rise from idle on a Classic is using too much filtering in the measurement or logging device (filters always cause delays).  The afonic link doesn't show the full ramp up - say 5 seconds, so I suspect that the data logger was filtering excessively and mostly erased the bump.

Interesting conclusions in your link on warmup (20 min) and stabilization (4 min).  A quick look at their data leads me to think 40 min and 15 min.
back to top
 View Profile Link to this post
D4F
Senior Member


Joined: 15 Mar 2012
Posts: 1,878
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Preciso
Posted Tue Aug 27, 2013, 12:27pm
Subject: Re: The 3 second bump
 

I am not making good sense of your "y" axis as temperature in the cup and if it is, what actual temperature?  Even moving decimal by 2 so 230F to 250F, should not be in the cup?

 
D4F also at
http://www.gaggiausersgroup.com/
back to top
 View Profile Link to this post
jonr
Senior Member


Joined: 25 Jun 2013
Posts: 258
Location: Americas
Expertise: I like coffee
Posted Tue Aug 27, 2013, 12:28pm
Subject: Re: The 3 second bump
 

I haven't calibrated the Y axis, just use it to show the idea.  Time = 17 is a good brew temp and after that it slowly falls off about 3C as I think tastes best.  Time = 14 is about 5C too hot.
back to top
 View Profile Link to this post
D4F
Senior Member


Joined: 15 Mar 2012
Posts: 1,878
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Preciso
Posted Tue Aug 27, 2013, 12:48pm
Subject: Re: The 3 second bump
 

If the "puck" basket and PF are say at about 190F, not an uncommon temperature to sit, and the brew temperature is say 200F then the whole "Y" axis is 10F and the up bump is small.  2000 on the scale is 10F and 200 - 300 is 1 - 1.5F and for a couple seconds.  You listed the reference about flat vs falling profile so you know that "flat" is not everyone's grail.  If I am approximate on the temperatures, then the peak could be set and the fall allowed, or not allowed. if you wish.  You could allow and count the bump as top and then be essentially flat after, but still cover only a couple of degrees.  I could be incorrect about the magnitude of what I am seeing, but it is about taste in the cup, not sensitive data points.

The bump is still real and I am not sure the cause, but is it really applicable.

 
D4F also at
http://www.gaggiausersgroup.com/
back to top
 View Profile Link to this post
jonr
Senior Member


Joined: 25 Jun 2013
Posts: 258
Location: Americas
Expertise: I like coffee
Posted Tue Aug 27, 2013, 1:05pm
Subject: Re: The 3 second bump
 

OK, I scaled the Y axis to degrees C from ideal.  The coffee grounds were still heating up so were not near to 190F just before brew.  Is a short term 5C bump taste-able?  Probably, but I don't know until I can get rid of it.

Do others wait until the coffee gets to 190F before brewing?  I load and go (the portafilter itself is still hot).
back to top
 View Profile Link to this post
D4F
Senior Member


Joined: 15 Mar 2012
Posts: 1,878
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Preciso
Posted Tue Aug 27, 2013, 1:35pm
Subject: Re: The 3 second bump
 

All this thinking makes my head hurt, may need an extra espresso, if I can find the proper temperature :)

I do not wait for coffee to warm and do not routinely have a thermofilter in.  Using a puck simulator and letting it sit 190F is reasonable.  I was trying to understand your method and scale and the discussion help me and probably others who read, thanks.

jonr Said:

My guess is that any graph that shows temp taking more than a couple seconds to fully rise from idle on a Classic is using too much filtering in the measurement or logging device (filters always cause delays).  The link doesn't show the full ramp up - say 6 seconds so I suspect that the data logger was filtering excessively and mostly erased the bump.

Posted August 27, 2013 link

I am not sure what the ramp up time is.  A division is 4s and the ramp up in the first plot of temp vs time in the Afonic link looks fairly quick, say half a division.

One other thought on the bump. Is it an up bump, or is it the real temperature and then a rapid fall down?  Is the cool incoming getting to the top faster than many measure so that the boiler water is initially the top temp and then cools, or is there a super heated layer on top.  What happens to the graph with a preheat bump and rest without adding brew heat?

 
D4F also at
http://www.gaggiausersgroup.com/
back to top
 View Profile Link to this post
jonr
Senior Member


Joined: 25 Jun 2013
Posts: 258
Location: Americas
Expertise: I like coffee
Posted Tue Aug 27, 2013, 1:55pm
Subject: 3 second bump
 

Some of the graphs here have a similar early bump (first graph, dark blue) of about 3C.

Click Here (coffeesnobs.com.au)

This one appears to suffer from filtering (ie, I wouldn't want to guess if there was a bump there or not):

http://coffeegeek.com/images/43730/allshots.jpg
back to top
 View Profile Link to this post
D4F
Senior Member


Joined: 15 Mar 2012
Posts: 1,878
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Preciso
Posted Tue Aug 27, 2013, 2:16pm
Subject: Re: Computer controlled boiler temp - better than PID
 

I do not see the bump quite the same, but more of a spike when the hot water registers and then a decline, not no much a pronounced bump/hump as yours.  That still could be sensor capability.  I did not note anything about a 3 - 4 sec blip of heat prior to the shot in the 2005 article.  In fact a note that full heat could not stop the initial drop and a plot showing that.  We use a 3 - 4 second pre-brew bump to stop that.

I still saw comments about taste in the cup back in 2005 when they were dealing with temperature control.  You may get less damping and filtering, but it still has to matter in the cup.

 
D4F also at
http://www.gaggiausersgroup.com/
back to top
 View Profile Link to this post
showing page 5 of 9 first page | last page previous page | next page
view previous topic | view next topic | view all topics
Discussions > Espresso > Espresso Mods > Computer...  
New Topics updated topics   New Posts new posts   Unanswered Posts new unanswered     Search Discussion Board search   Discussion Board FAQ faq   Signup sign up  
Not Logged in: Log In to Postlog in
Discussions Quick Jump:
Symbols: New Posts= New Posts since your last visit      No New Posts= No New Posts since last visit     Go to most recent post= Newest post
Forum Rules:
No profanity, illegal acts or personal attacks will be tolerated in these discussion boards.
No commercial posting of any nature will be tolerated; only private sales by private individuals, in the "Buy and Sell" forum.
No SEO style postings will be tolerated. SEO related posts will result in immediate ban from CoffeeGeek.
No cross posting allowed - do not post your topic to more than one forum, nor repost a topic to the same forum.
Who Can Read The Forum? Anyone can read posts in these discussion boards.
Who Can Post New Topics? Any registered CoffeeGeek member can post new topics.
Who Can Post Replies? Any registered CoffeeGeek member can post replies.
Can Photos be posted? Anyone can post photos in their new topics or replies.
Who can change or delete posts? Any CoffeeGeek member can edit their own posts. Only moderators can delete posts.
Probationary Period: If you are a new signup for CoffeeGeek, you cannot promote, endorse, criticise or otherwise post an unsolicited endorsement for any company, product or service in your first five postings.
Cafe Espresso Machines
Video reviews, nationwide installation, leasing options... Nuova Simonelli, Rancilio, La Marzocco.
www.seattlecoffeegear.com
Home | Opinions | Consumer Reviews | Guides & How Tos | CoffeeGeek Reviews | Resources | Forums | Contact Us
CoffeeGeek.com, CoffeeGeek, and Coffee Geek, along with all associated content & images are copyright ©2000-2014 by Mark Prince, all rights reserved, unless otherwise indicated. Content, code, and images may not be reused without permission. Usage of this website signifies agreement with our Terms and Conditions. (0.342802047729)
Privacy Policy | Copyright Info | Terms and Conditions | CoffeeGeek Advertisers | RSS | Find us on Google+