HomeRoast Digest


Topic: Yama tabletop on the way! (8 msgs / 233 lines)
1) From: Bryan Wray
Well I am finally starting to cash in some of the SM gift certificates that I got for Christmas and I chose to get actual items with them instead of coffee (I like taking this approach because then the person can see an item for a long time instead of me saying that I purchased this bean or that and that it was great...).  So, with one $40 gift certificate I purchased a (with a little help from my own pocket) Yama tabletop.  I have never used a vacuum brewer before (have had coffee from one) and am looking forward to the learning curve.  I don't really understand the tip sheets yet, but I also don't have the brewer in front of me and I'm sure I will understand when all the parts are in front of me.  I still don't understand how vacuum brewing works, to be honest, but I guess I will when I see it happen.  Boiling water=bad for coffee, so is there a vacuum created in the lower part meaning that the water is boiling at a lower temperature?  I guess I just should have payed
 more attention in science class... I don't know.  If anyone would care to enlighten me on this that would be great, but it's okay if I just have a sort of "figure it out on your own" approach to it.
Either way, I'm really excited to have a Yama on the way (and a double 8 pack, just to be safe)
-Bry
Bryan Wray
NaDean's Coffee Place
Kalamazoo, MI
"It is my hope that people realize that coffee is more than just a caffeine delivery service, it can be a culinary art"- Chris Owens of Cafe Grumpy in NYC.
       
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2) From: John Despres
It's all about atmospheric pressure and vacuums.
Once the water in the bottom chamber starts heating up, the pressure 
decreases in that chamber while, relatively, the pressure on the 
exterior increases and forces the water out and into the top bowl 
thereby creating a vacuum in the lower as it cools and subsequently 
draws the brew down...
For a fun experiment, take a metal can (my dad used to do this for us as 
kids with a gallon maple syrup can) with a screw top lid, add a bit of 
water and close the lid tightly. Put it on the stove and slowly heat it. 
As the water warms, the exterior pressure will "increase" and the can 
will begin to collapse...
Very fun, this science!
John
Bryan Wray wrote:
<Snip>
-- 
John A C Despres
Hug your kids
616.437.9182http://www.sceneitallproductions.com

3) From: Dave Ehrenkranz
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Bryan,
I suspect you may have meant to say "Once the water in the bottom  
chamber starts heating up, the pressure INCREASES in that chamber  
while, the pressure on the exterior IS ATMOSPHERIC PRESSURE (BUT LESS  
THAN THE LOWER CHAMBER) and forces the water out and into the top  
bowl...."
When the heat is removed from the lower bowl and it cools the  
pressure decreases (creating a "vacuum") in the lower bowl but the  
pressure in the upper bowl is still ATMOSPHERIC PRESSURE but now  
larger than the lower bowl thereby  pushing the liquid into the lower  
bowl.
I have not used a Yama but I believe I understand the process. Fill  
free to correct me if I misunderstood.
dave
On Jan 5, 2008, at 3:24 PM, John Despres wrote:
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Bryan,I suspect you may =
have meant to say "Once the water in the bottom chamber starts heating =
up, the pressure INCREASES in that chamber while, the pressure on the =
exterior IS ATMOSPHERIC PRESSURE (BUT LESS THAN THE LOWER CHAMBER) and =
forces the water out and into the top bowl...."
When the heat is removed = from the lower bowl and it cools the pressure decreases (creating a = "vacuum") in the lower bowl but the pressure in the upper bowl is = still ATMOSPHERIC PRESSURE but now larger than the lower bowl = thereby  pushing the liquid into the lower bowl.
I have not used a Yama but = I believe I understand the process. Fill free to correct me if I = misunderstood.
dave
On Jan 5, = 2008, at 3:24 PM, John Despres wrote:

It's all about atmospheric = pressure and vacuums.

Once the water in the bottom = chamber starts heating up, the pressure decreases in that chamber while, = relatively, the pressure on the exterior increases and forces the water = out and into the top bowl thereby creating a vacuum in the lower as it = cools and subsequently draws the brew down...

For a fun experiment, take a metal can (my dad used to do = this for us as kids with a gallon maple syrup can) with a screw top lid, = add a bit of water and close the lid tightly. Put it on the stove and = slowly heat it. As the water warms, the exterior pressure will = "increase" and the can will begin to collapse...

Very fun, this science!

=

John

Bryan Wray wrote:

= = --Apple-Mail-6-80769226--

4) From: Rich
Dave, I would say you got it right.
Dave Ehrenkranz wrote:
<Snip>

5) From: Bryan Wray
That's kind of what I thought but couldn't put into words, thanks for the response.
-Bry
 
Bryan Wray
NaDean's Coffee Place
Kalamazoo, MI
"It is my hope that people realize that coffee is more than just a caffeine delivery service, it can be a culinary art"- Chris Owens of Cafe Grumpy in NYC.
       
---------------------------------
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6) From: John Despres
Arrrgh! I (Not Bryan) got it backwards, and that's most embarassing...
Sheesh! I know better, too...
John
Dave Ehrenkranz wrote:
<Snip>
-- 
John A C Despres
Hug your kids
616.437.9182http://www.sceneitallproductions.com

7) From: Brett Mason
Water gets hot.
Expands.
  A lot.
Sealed at top.
Escapes through funnel.
  Up.
Stays there once pressure equalizes.
Heat turns off.
Bottom cools.
Moist air contracts.
  Coffee descends.
Done once pressure equalizes.
  Yum.
There's science in there somewhere.
For me, there's coffee....
  Brett
On Jan 6, 2008 8:11 AM, John Despres  wrote:
<Snip>
-- 
Cheers,
Bretthttp://homeroast.freeservers.com

8) From: John Despres
This is a multi-part message in MIME format.
Nature abhors the vacuum in my brain...
John
Brett Mason wrote:
<Snip>
-- 
John A C Despres
Hug your kids
616.437.9182http://www.sceneitallproductions.com


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