Our Valued Sponsor
OpinionsConsumer ReviewsGuides and How TosCoffeeGeek ReviewsResourcesForums
Espresso: Espresso Mods and Restorations
Air driven shot to increase thermal stability of small boiler?
Home Espresso Machines
Watch videos with Gail & Kat, Rocket, Jura Capresso, Saeco, Rancilio, Quick Mill, Nespresso
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 > Air driven shot...  
view previous topic | view next topic | view all topics
showing page 1 of 3 last page next page
Author Messages
jonr
Senior Member


Joined: 25 Jun 2013
Posts: 290
Location: Americas
Expertise: I like coffee
Posted Sat Jun 29, 2013, 6:15pm
Subject: Air driven shot to increase thermal stability of small boiler?
 

I have a couple of Gaggia espresso machines (Classic and Espresso) that have a small boiler.  While some people have shown good intra shot temperature stability, others have seen a big drop.  There have also been mentions of slow pressure ramp up time and rapid pressure fluctuations caused by the pump.

I'm considering using air pressure to push the shot out.  Ie, make sure the boiler is full and everything is fully heated.  Then introduce 9 bar air to the top of the boiler.  This should push the shot out without bringing cooler water into the boiler and pulling down the temperature.  

It looks like it's easy to do, with the major effort being the removal of the copper tube inside the boiler that causes water to be drawn from the top.  A restriction in the air line could be added to slow down pressure ramp up.  Is using air vs a water pump likely to buy me anything?
back to top
 View Profile Link to this post
D4F
Senior Member


Joined: 15 Mar 2012
Posts: 1,981
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Baratza Forte-AP
Posted Sat Jun 29, 2013, 7:33pm
Subject: Re: Air driven shot to increase thermal stability of small boiler?
 

Jonr, happy to see your new thread/topic.

First I want to be sure of the machine, I think you mean this

http://www.partsguru.com/user/Espresso-Espresso%20Deluxe.pdf

You mentioned air through the top, and I believe that you mentioned through the steam arm, copper tube.  Many Gaggias drip through the steam valve out the wand.  The valve is not usually totally sealed, so a potential area of problem, but you are going in reverse if. You could remove the valve assembly and make an air insert there.  Outward from the valve, the tube to valve compression fitting may not be 9 bar competent.  There is an o-ring type seal on the needle valve that fails and can be seen in the thread below, and it is used seeing steam pressure, not 9 bar.

http://coffeegeek.com/forums/espresso/machinemods/607264

You could make a top fitting as in this thread

Click Here (coffeegeek.com)

He inserted a thermocouple, but you could use a similar top block and add your air valving.

The Gaggia Espresso has a tank return valve/line off the steam valve that will need to be sealed.

Will 9 bar of back pressure to the non-running pump cause problem or leak?

All of these are really minor to check and fix, just speed bumps on the way.

I might only remove a part of the central copper tube.  Leaving say half will keep the boiler from emptying itself, obviously water will only go dowm to the level.  A empty boiler could heat very quickly without any water to buffer, transfer, and distribute heat.  Probably ok as the elements are external, but why take a chance?  Don't know whether air will "buy you anything" but should not have to cost you anything.

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


Joined: 6 Jul 2011
Posts: 19
Location: Chesterfield, VA
Expertise: I love coffee

Espresso: Elektra Micro Casa,...
Grinder: La Cimbali 6S, Baratza...
Drip: EVA Solo, Moka, Press Pot,...
Posted Sun Jun 30, 2013, 5:31am
Subject: Re: Air driven shot to increase thermal stability of small boiler?
 

Good luck with your modifications, realize that you may not need (want) to put 9 bar of pressure on the boiler.

You mentioned putting 9 Bar (~ 130PSI) on the boiler this could cause higher pressure at the PF.  Pressure is area based, you will need to check how much pressure you need to apply at the boiler to have 9 bar at the PF.

Jim
back to top
 View Profile Link to this post
kolu
Senior Member
kolu
Joined: 28 May 2013
Posts: 28
Location: Prague, Czech Republic
Expertise: I like coffee

Espresso: Faema E92 SE, Futuramat...
Grinder: Mazzer SJ, Macap M4D,...
Drip: Kalita Wave
Posted Sun Jun 30, 2013, 6:33am
Subject: Re: Air driven shot to increase thermal stability of small boiler?
 

Most problems with Gaggia Espresso (Color, Dose and similar) machines bad intra-shot temperature stability and pressure is due to self-priming valve leakage - that can be fixed by permanently sealing that valve and priming the boiler manually with steam valve (which youll need to do even in case of using the "air pump"). So I strongly suggest you to start with the self-priming valve.
Gaggia Classic machines have different boiler - aluminium with heaters on the outside of boiler. Can't say much about that since I have Espresso Dose at home, not Classic.

"Pressure is area based": Not exactly as far as I understand the matter. Pressure (pressure=force/area) is the same in stationary state in any point of closed system. So 9 Bar at the output of brew pump = 9 Bar inside the boiler = 9 Bar at the PF. Basically, ignoring small dynamic loses due to fluid motion...
back to top
 View Profile Link to this post
jroach
Senior Member


Joined: 6 Jul 2011
Posts: 19
Location: Chesterfield, VA
Expertise: I love coffee

Espresso: Elektra Micro Casa,...
Grinder: La Cimbali 6S, Baratza...
Drip: EVA Solo, Moka, Press Pot,...
Posted Sun Jun 30, 2013, 7:06am
Subject: Re: Air driven shot to increase thermal stability of small boiler?
 

If you look at an air over hydraulic system (common cylinder amplifiers for using air pressure to obtain high forces) the PSI on the reduced area hydraulic (H20 here) system is high to balance for the reduced area. The force of the air (total force=130 psi X area) = total force of the hydraulic system (Area at PF x hydraulic/water pressure).  

You got me on verbiage, pressure is force over area, but in the system you will likely have to different areas so if the force is constant and the areas change, the pressure needs to balance the equation.  Unless I'm missing something.  

Ciao
Jim
back to top
 View Profile Link to this post
jonr
Senior Member


Joined: 25 Jun 2013
Posts: 290
Location: Americas
Expertise: I like coffee
Posted Sun Jun 30, 2013, 9:21am
Subject: Re: Air driven shot to increase thermal stability of small boiler?
 

OK, I plugged the "auto prime valve" that the Expresso has.  That may be a good air entry point for a more permanent setup.  

Good point about not cutting the copper riser tube down too far.  I suppose if I get it just right, the tube will conveniently start drawing air exactly as I reach a 2 oz shot.

An ideal research machine would allow me to control pressure or flow over time (ie, pressure profiling).  There may be dynamically controllable air pressure regulators, but I haven't seen one.  And then there is temperature profiling, which isn't very compatible with the air shot idea of keeping it steady (by not introducing cool water).  Bill C's cold/hot water mixing valve concept makes more sense for that.

I see no consensus on the benefits of temperature or pressure profiling vs steady temp and pressure.  Did I miss something?
back to top
 View Profile Link to this post
CoffeeRon
Senior Member
CoffeeRon
Joined: 26 Apr 2009
Posts: 733
Location: Tacoma Wa.
Expertise: I love coffee

Espresso: Wega Lyra, Europiccola(still...
Grinder: Macap M7D, Pharos, Vario W,...
Vac Pot: Sunbeam CoffeeMaster
Drip: Melita BCM-4
Roaster: FR SR500,B-1600, SC/TO
Posted Sun Jun 30, 2013, 9:56am
Subject: Re: Air driven shot to increase thermal stability of small boiler?
 

jroach Said:

If you look at an air over hydraulic system (common cylinder amplifiers for using air pressure to obtain high forces) the PSI on the reduced area hydraulic (H20 here) system is high to balance for the reduced area. The force of the air (total force=130 psi X area) = total force of the hydraulic system (Area at PF x hydraulic/water pressure).  

You got me on verbiage, pressure is force over area, but in the system you will likely have to different areas so if the force is constant and the areas change, the pressure needs to balance the equation.  Unless I'm missing something.  

Ciao
Jim

Posted June 30, 2013 link


True the force changes with the area, but as the force is measured "per square inch" you are working with a constant. 130 pounds per square inch is what it is regardless of whether its pushing one square inch or five. You can increase the force on a cylinder by increasing the cylinder size, but if you provide 9 bars of force in a system then the 9 bars will be a constant within the system. Does that make sense?
back to top
 View Profile Link to this post
calblacksmith
Moderator
calblacksmith
Joined: 25 Nov 2007
Posts: 7,672
Location: Riverside, Ca, U.S.A.
Expertise: I live coffee

Espresso: ECM Vene. A1, La Cimbali M32
Grinder: Azkoyen Capriccio, Major
Vac Pot: 40s era Silex
Drip: Msl. Com. brewers
Roaster: gave it a try, decided no
Posted Sun Jun 30, 2013, 10:11am
Subject: Re: Air driven shot to increase thermal stability of small boiler?
 

OH, BTW, Have you thought about what you are going to do inside the boiler so that you do not uncover the heater and burn it up by replacing makeup water with air?
Steaming uses less water and you refill the boiler right away. If you try to pull multiple shots from the same boiler heat cycle by avoiding filling the boiler with cold water, you take too much water from the small boiler and uncover the heating element.

 
In real life, my name is
Wayne P.
Anything I post is personal opinion and is only worth as much as anyone else's personal opinion. YMMV!

Feed the newbs, starve the trolls and above all enjoy what you drink!
back to top
 View Profile Visit website Link to this post
jonr
Senior Member


Joined: 25 Jun 2013
Posts: 290
Location: Americas
Expertise: I like coffee
Posted Sun Jun 30, 2013, 12:14pm
Subject: Re: Air driven shot to increase thermal stability of small boiler?
 

With the Classic and Espresso, the heating coils and the thermostat are both in the walls of the boiler.  So heating without water (or in my case, with only 1.5 oz remaining) should not cause any overheating or damage.  Agreed, this is not true of many other boiler designs.  On those, you may need to leave the boiler off after you start extraction (which should be fine,  you don't need to be adding heat).

My guess is that air drive (and PID) would add excellent temp and pressure consistency to just about any small boiler espresso machine.  Of course it requires a compressed air source, but at $100 + a few fittings, that is cheaper than a better machine.
back to top
 View Profile Link to this post
D4F
Senior Member


Joined: 15 Mar 2012
Posts: 1,981
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Baratza Forte-AP
Posted Sun Jun 30, 2013, 12:52pm
Subject: Re: Air driven shot to increase thermal stability of small boiler?
 

I will assume that you know that air/gas driven works in the Myprressi Twist, but a mention of it to make sure.  You are doing air in a boiler, so different, but still gas driven, so I do not know if there is anything to be learned from that system.

 
D4F also at
http://www.gaggiausersgroup.com/
back to top
 View Profile Link to this post
showing page 1 of 3 last page next page
view previous topic | view next topic | view all topics
Discussions > Espresso > Espresso Mods > Air driven shot...  
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.
Commercial Equipment
Nuova Simonelli, La Marzocco, Rancilio. Nationwide installation. Instant financing options.
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. (0.25425696373)
Privacy Policy | Copyright Info | Terms and Conditions | CoffeeGeek Advertisers | RSS | Find us on Google+