ethorson Senior Member Joined: 4 May 2009 Posts: 50 Location: Port Townsend Expertise: Just starting
Espresso: Bunn ES-1A, Bezzera BZ35 Grinder: Mazzer Mini Roaster: Homemade
Posted Tue Jan 19, 2010, 2:17pm Subject: Re: Barista's Nightmare
Degull Said:
I'm restoring a Bunn ES-1A as well. Not going to attempt what you have done but I have a few things in mind. I'd like to add a temperature thermometer to the group. I was wondering if you can let me know which port on the top of the group you used and how did you affix the probe? Did you have to make something or did you find some fitting? Do have any close up pics?
I have attached a photo showing the fitting used to install the temperature gauge in place of the large plug on the group. I have a lathe and made this fitting along with many others for this machine. By now I am really good at cutting metric and BSP threads! The gauge had a long stem that required removal of the stock gicleur (see photo), which was replaced with a custom machined shorter version. You can't really do this on a stock ES-1A because the gicleur has to be where it is in order to purge air from the thermosyphon loop. In my case the boiler is higher and I have an alternate purge port at the top of the heat exchanger.
If you want to measure the group thermosyphon temperature I would suggest that you use a thermocouple probe. You could drill a hole in the plug and insert a small probe inside the spring that holds the gicleur in place. Some sort of seal would be needed that could withstand 150 psi of 250 F water.
Degull Senior Member Joined: 8 Nov 2009 Posts: 24 Location: Toronto Expertise: Just starting
Posted Tue Jan 19, 2010, 5:37pm Subject: Re: Barista's Nightmare
It's a good thing you mentioned the spring etc under the larger nut. I'm missing all the parts under my large nut!! The spring, injector etc is missing. Going to have to source those parts!! Looks like there are two different build ups, not sure which one I have.
Back to the temp probe. I'm wondering if I can drill and tap a spot on the group? Is the small nut on top for thermosyphon water as well?
Posted Tue Jan 19, 2010, 6:12pm Subject: Re: Barista's Nightmare
Degull Said:
It's a good thing you mentioned the spring etc under the larger nut. I'm missing all the parts under my large nut!! The spring, injector etc is missing. Going to have to source those parts!! Looks like there are two different build ups, not sure which one I have.
I've been following what you're saying/posting on BUG & here. there's a 6mm & 8mm size. I haven't looked in ages, but I'm sure it's 8mm. I'll have to refresh my memory with the group internal pics. All the parts & group pics Tex has links & or pics of all parts needed.
Degull Senior Member Joined: 8 Nov 2009 Posts: 24 Location: Toronto Expertise: Just starting
Posted Tue Jan 19, 2010, 6:27pm Subject: Re: Barista's Nightmare
Yes if you look at the diagram FUTURMAT MODERN CFE SOLENOID GR.pdf in the files section of the ES-1A section, the diagram shows the long hex nut with description as either a 6mm or 8mm thread column. I have that part. I'm missing everything above the thread column.
I hate to hijack your thread, should I start another?
Degull Senior Member Joined: 8 Nov 2009 Posts: 24 Location: Toronto Expertise: Just starting
Posted Tue Jan 19, 2010, 6:45pm Subject: Re: Barista's Nightmare
To answer my own question about measuring group head temp it looks as though using the small nut would be ideal. This chamber leads directly to the diffuser and portafilter. Wouldn't this be the best spot to measure temp or am I missing something?
Posted Tue Jan 19, 2010, 6:56pm Subject: Re: Barista's Nightmare
Degull Said:
To answer my own question about measuring group head temp it looks as though using the small nut would be ideal. This chamber leads directly to the diffuser and portafilter. Wouldn't this be the best spot to measure temp or am I missing something?
I believe it would be, as the group doesn't have a/the 6mm threaded cap screw that threads into the port in the front sloped area of the group as on a/my Expobar Office EB-61 Leva (Lever). In both instances it's leading to the same spot or place where a thermocouple or Erics adapter (with digital thermometer) would reach for measurement anyway.
P.S. We could chat & talk about this on Windows Live Messenger. Or email me & we can exchange phone numbers & talk about our BUNN ES-1A's some or anytime! {;-)
ethorson Senior Member Joined: 4 May 2009 Posts: 50 Location: Port Townsend Expertise: Just starting
Espresso: Bunn ES-1A, Bezzera BZ35 Grinder: Mazzer Mini Roaster: Homemade
Posted Tue Jan 19, 2010, 7:26pm Subject: Re: Barista's Nightmare
Degull Said:
To answer my own question about measuring group head temp it looks as though using the small nut would be ideal. This chamber leads directly to the diffuser and portafilter. Wouldn't this be the best spot to measure temp or am I missing something?
There is actually an advantage to measuring the thermosyphon temperature under the big nut that I didn't anticipate before doing this project. When you do a cooling flush you can see the temperature drop at the group both during the flush and after its termination. The temperature will continue to undershoot as cold water injected into the heat exchanger makes its way to the group. I use the temperature reading to determine when to start the shot, which results in very repeatable extraction temperatures at the puck.
Measuring the temperature under the small nut does give a reading closer to that at the puck but is only valid when water is flowing (group solenoid on). Otherwise the preinfusion chamber is empty and the temperature measurement probably invalid. I think the other location gives better information for producing repeatable shots. In either case you need to use a portafilter thermocouple (Scace device) to establish the operating parameters.
Degull Senior Member Joined: 8 Nov 2009 Posts: 24 Location: Toronto Expertise: Just starting
Posted Wed Jan 20, 2010, 7:54am Subject: Re: Barista's Nightmare
That's a good point and I think I will experiment with both. I can order both top nuts from cafeparts.com for only a few dollars if I decide to go back to stock. I'm going to drill and tap both of the top nuts to allow the addition of a thermocouple. I'll just move the thermocouple between the two to see what works best. I really appreciate your help! Thanks!
Symbols: = New Posts since your last visit = No New Posts since last visit = 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 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.
![ethorson: Group1.jpg](javascript:ImagePopup("/images/46797/Group1.jpg", 640, 901, "ethorson: Group1.jpg");)
= No New Posts since last visit 