Posted Sat Mar 5, 2005, 6:18pm Subject: Re: Fine Tuning Brew Temperature on a Heat Exchanger Machine
singforsupper Said:
That is indeed a great chart. On my Briccoletta, I have a direct connect to the water line and I have a drain hose on my drip pan. Therefore, I just run about 10-11 oz. of water through the group head if it's been setting for a while. Would that make sense? If there's no need to be concerned about the volume of water used nor the water level of the drip pan, then is the chart still applicable?
The chart is applicable regardless of your water source. Your water source may only affect the rebound time (recovery time) if the water temperature in your pipe is lower than 80f. Allow a few more seconds in such case for recovery. 11 oz is too much. 8-8.5 oz will empty the H/X on most prosumer machines, so you would not want to go over that. Your temperature will drop below brew temperature and you will need a much longer recovery time if you do. If you cannot measure your brew temperature, follow the chart as is, and add a few seconds to your recovery time. Setting your boiler pressure to 1.1 bars would also help.
Hi Eric, I guess I'll tell you more than you asked! In the end, I really didn't need a chart. I guess I just played around with this so much that I can now come within a degree or two of my desired brew temperature without using a chart. The most important flush is that first one. If you have a way to measure the temperature of the water coming out of the group, and you learn how long an initial flush you need to get to a desired target temperature (by deciding what temp gives you the best cup quality), and then you stop the flush there, all the rest will quite easily fall into place. On my Andreja, I cut the initial flush off at around 200 deg F, down from 212 deg F. Initially, it takes a bunch of measuring and some time but after you go through it you'll be able to hit the target brew temp dead on and after that, you won't need to measure temps again. All you'll need to do is a 2-ounce flush, wait 30 seconds and pull the shot. That's it! Timing the flush will be enough. 2 oz takes 8 sec on my machine. It sounds harder than it is.
Just by coincidence, yesterday, I was curious, after months of pulling shots intuitvely, how consistent my brew temps were. So I pulled out my PF with an embedded TC, data-logged a bunch of shots and posted the results on another coffee forum. I found out that I can still pull shots to within the same temperature tolerances by getting the flush timing just right. I don't measure the water amounts; just the flush time.
Here is a chart showing part of what I did yesterday and really, what I do every day. The temps are the Y axis and the time in one-minute intervals is the X axis. Although this graph doesn't show the very first 25-second flush, these are the flushes after that. The first peak in each group is a 2-ounce flush. The second is a 2-oz shot pull. Note the relatively consistent temps of all the shot pulls even though the time between flushes changes (by design). The temps don't vary by more than a degree or two. This is a very stable and consistent process.
jakethecoffeelover Senior Member Joined: 3 Mar 2005 Posts: 1,036 Location: Vancouver, British Columbia, Canada Expertise: Pro Barista
Espresso: Gaggia Espresso Grinder: Mazzer Super Jolly... Vac Pot: Perhaps in the future... Drip: Insulated Bodum Kenya FP Roaster: Hearthware iRoast
Posted Thu May 19, 2005, 7:46pm Subject: Re: Fine Tuning Brew Temperature on a Heat Exchanger Machine
Remember that many people advise people to start the shot at high temperature so as to neutralize the sour notes as the shot comes out, especially with pre-infusion. While I'm here, I figure I'll give a little and get a little. I have a question. When you pull a normal doppio shot, that means that 2oz of water goes through the heat exchanger in 25 seconds. For the sake of getting an answer, let's assume that this is always true. Now, when you pull a ristretto, only 1oz of water goes through the HX in 25 seconds. Therefore, the water ends up sitting in that tube surrounded by 125C water for longer. That means that the brewing temperature will be higher. Is this a major problem with HX machines? Is there a way around it either than what I plan to do when I modify my machine and temperature probe the steam boiler for control?
Posted Thu May 19, 2005, 11:50pm Subject: Re: Fine Tuning Brew Temperature on a Heat Exchanger Machine
Jake - most HX machince have an pressure valve that limits the water pressure going to the grouphead. Excess pressure (and therefore excess water flow) is rerouted to a seperate line which in most cases flows into the drip tray. FOr your example of pulling a rsitretto, the same amount of water will purge form the HX coil, but some will go to the grouphead, and the remainder will go to the tray. Make sense?
jakethecoffeelover Senior Member Joined: 3 Mar 2005 Posts: 1,036 Location: Vancouver, British Columbia, Canada Expertise: Pro Barista
Espresso: Gaggia Espresso Grinder: Mazzer Super Jolly... Vac Pot: Perhaps in the future... Drip: Insulated Bodum Kenya FP Roaster: Hearthware iRoast
Posted Fri May 20, 2005, 12:25am Subject: Re: Fine Tuning Brew Temperature on a Heat Exchanger Machine
Nice that makes perfect sense. Thanks. You really know how to explain these things! It's the only thing left I definitely need to know in order to make my mods! I won't have time until provincial exams are over though... end of June!
Glad to help. And, not to beat a dead horse, once you settle on an approximate routine, it will all become second nature. That chart was just a spontaneous sanity check that I did out of curiosity after months of not measuring anything, not time, or volume, or anything. I count the seconds in my head if I have to, and judge the volume by how much it fills a cup. One additional thing that helps... The initial 6-oz flush just fills a cappa cup to the brim and preheats it as well! So I use that little trick when my first drink of the day is a cappa, which it often is.
Posted Fri May 20, 2005, 2:47am Subject: Re: Fine Tuning Brew Temperature on a Heat Exchanger Machine
boby Said:
Here is a chart showing part of what I did yesterday and really, what I do every day....Note the relatively consistent temps of all the shot pulls even though the time between flushes changes (by design). The temps don't vary by more than a degree or two. This is a very stable and consistent process.
Do you have graphs that focus on the actual shot pulls? With perhaps, a one or two second interval on the X axis?
I understand the point you're making, but that graph just indicates that the temp are fairly consistent. There isn't enough detailed information to make the earth-shaking conclusions that we strive to make on Coffeegeek. :-)
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.
![boby: Andreja 5_18_05.jpg](javascript:ImagePopup("/images/17420/Andreja5_18_05.jpg", 1102, 324, "boby: Andreja 5_18_05.jpg");)
= No New Posts since last visit 