Our Valued Sponsor
OpinionsConsumer ReviewsGuides and How TosCoffeeGeek ReviewsResourcesForums
Espresso: Espresso Mods and Restorations
Electronic PSTAT??
Learn @seattlecoffeegear
Learn all about coffee, watch videos, read how-to articles.
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 > Electronic...  
view previous topic | view next topic | view all topics
Author Messages
lparsons21
Senior Member


Joined: 8 Jul 2006
Posts: 310
Location: Herrin, IL
Expertise: I love coffee

Espresso: Izzo Alex
Grinder: Mazzer SJ, Ascaso i2,...
Roaster: Gene Cafe, Behmor,...
Posted Tue Mar 25, 2014, 8:41am
Subject: Electronic PSTAT??
 

Since I modded my Izzo Alex (2006 model) with a SSR to replace the old mechanical relay that would last less than a year, I've been very pleased with the resullts.  The two big things that made me happy with the mod was the lack of the very noisy relay and knowing that the SSR has lasted so long.

Now I'm thinking that maybe a PSTAT mod is something that could be a good idea.  The current mechanical one has worked just fine, I'm on my 2nd one in 7 years, but it seems to me that there should be a non-mechanical version of a PSTAT yet I can't seem to find one.

Any suggestions?  Or is this just fodder for discussion??  :)

Thanks

 
Lloyd
back to top
 View Profile Link to this post
skydragondave
Senior Member


Joined: 18 Feb 2013
Posts: 167
Location: Ontario, Canada
Expertise: Professional

Espresso: Commercial Only
Grinder: Commercial Only
Roaster: Has Garanti HG5
Posted Tue Mar 25, 2014, 5:21pm
Subject: Re: Electronic PSTAT??
 

Certain commercial models of espresso machine have electronic pressure regulation. It consists of an electronic thermistor threaded into the boiler, a separate circuit built into the electronic board, and a solid state relay. The Spaziale S5 for example does this. A thermistor also allows the board to be equipped with a digital display that shows real-time temperature of the steam boiler (which is only really useful as the machine is warming up). The problem is cost of the components and potential failure of the electronic control board rendering the machine inoperative, whereas on a semi-automatic machine with a simple autofill board, if the board is taken out by a power surge, the boiler can be refilled with the manual valve and the machine can still be used. Likewise, the MATER pressurestat and SSR can be used without a functioning electronic board.
Pressure and temperature are directly related in a pressure vessel, so either data set can be used as a means of control. Pressurestats are more commonly used on HX machines because brew temperature is more a function of the dimensions of the heat exchanger, length of the injector tube, size of the thermosyphon loop restrictors (if used) or wattage of the group thermoblock or plug heater (if used). If left to idle, the temperature of the water inside the exchanger will always rise to steam boiler water temperature which is always higher than brew temperature; which is why using a PID to control steam boiler temperature is kind of pointless: the overheated water always has to be purged from the inside of the heat exchanger until water reaching the puck is of the correct temperature. You do this by operating the group with portafilter removed until flash-boiling of the brew water stops.
back to top
 View Profile Link to this post
lparsons21
Senior Member


Joined: 8 Jul 2006
Posts: 310
Location: Herrin, IL
Expertise: I love coffee

Espresso: Izzo Alex
Grinder: Mazzer SJ, Ascaso i2,...
Roaster: Gene Cafe, Behmor,...
Posted Tue Mar 25, 2014, 5:35pm
Subject: Re: Electronic PSTAT??
 

Interesting info, and I could see something like that in a commercial machine.

I was thinking much simpler.  A pstat is switching at line voltage levels of I understand it right.  I was thinking of something like the SSR, but controlling the switching of the SSR with a pressure switch that would just short when needing more pressure/heating.  IOW, let an SSR do the higher voltage switching.  That would extend the life of the PSTAT I would think.

 
Lloyd
back to top
 View Profile Link to this post
skydragondave
Senior Member


Joined: 18 Feb 2013
Posts: 167
Location: Ontario, Canada
Expertise: Professional

Espresso: Commercial Only
Grinder: Commercial Only
Roaster: Has Garanti HG5
Posted Wed Mar 26, 2014, 4:10am
Subject: Re: Electronic PSTAT??
 

The MATER pressurestat has lower current contacts designed for switching SSRs. It also has an adjustable deadband so you can tighten on/off cycles. There is also a pressure switch available with a microswitch sticking out the side of it that is meant to control mechanical relays. Your existing pressurestat is probably one of these two designs and if there's a difference between them and the one you're proposing, I'm not understanding it from your description. A MATER pressurestat and SSR is as simple and precise as it gets without a PID.
back to top
 View Profile Link to this post
lparsons21
Senior Member


Joined: 8 Jul 2006
Posts: 310
Location: Herrin, IL
Expertise: I love coffee

Espresso: Izzo Alex
Grinder: Mazzer SJ, Ascaso i2,...
Roaster: Gene Cafe, Behmor,...
Posted Wed Mar 26, 2014, 6:04am
Subject: Re: Electronic PSTAT??
 

Ah, so then I'm not switching line (110VAC) with the PSTAT?

For some reason I kept thinking it did.  Thanks for the explanation.

 
Lloyd
back to top
 View Profile Link to this post
skydragondave
Senior Member


Joined: 18 Feb 2013
Posts: 167
Location: Ontario, Canada
Expertise: Professional

Espresso: Commercial Only
Grinder: Commercial Only
Roaster: Has Garanti HG5
Posted Wed Mar 26, 2014, 11:19am
Subject: Re: Electronic PSTAT??
 

You are switching line voltage with the MATER pressurestat but the SSR it is powering requires less current and the SSR does not have moving contacts handling the high current to the heating element, so it is less likely to fail.
back to top
 View Profile Link to this post
witoldb
Senior Member


Joined: 15 Aug 2013
Posts: 111
Location: Dubai UAE
Expertise: I like coffee

Espresso: Sanremo Treviso LX,...
Grinder: Vario,Elektra MXS,...
Roaster: DIY 250g drum roaster
Posted Wed Mar 26, 2014, 11:35am
Subject: Re: Electronic PSTAT??
 

Check my circuit in this HB thread:
Click Here (www.home-barista.com)
It's my second installation in the machine (1st was for Sanremo Treviso LX) and works perfectly.
I can hardly see any movement of the gauge needle when SSR goes on and off.
back to top
 View Profile Link to this post
view previous topic | view next topic | view all topics
Discussions > Espresso > Espresso Mods > Electronic...  
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 Solutions
Commercial sales and service, nationwide installation, equipment leasing 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. (0.206435203552)
Privacy Policy | Copyright Info | Terms and Conditions | CoffeeGeek Advertisers | RSS | Find us on Google+