HomeRoast Digest


Topic: Z&D quick look, 2nd try (5 msgs / 159 lines)
1) From: dewardh
My first attempt to post this seems to have gone to the "bit bucket in the sky" 
.. . . watch it suddenly appear when I post this "second try" . . .
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Well . . . I've put a few roasts through my Z&D now, and partially disassembled 
it for a look-see, and I'm both impressed and disappointed.  The machine has 
some novel, and very neat, features, and a couple of the not-at-all-novel, in 
fact all-too-common, home roaster flaws.
The novel and good are both pretty obvious . . . the catalytic smoke 
eliminator, and the mechanical (screw) stirrer.
The "smoke-eater" is a miniature version of the honeycomb catalytic device you 
find in some "high efficiency low pollution" wood stoves, and has its own 
dedicated heater to keep it hot and working throughout the roast and cooldown 
cycles.  It has its own fan, too (on a common shaft with the heater fan), to 
draw roast air through the heater/catalyst . . . without that fan (which sucks 
air through the "converter" from the roast chamber) the back pressure of the 
catalytic device would pose serious problems in sealing the roast chamber and 
maintaining airflow across the primary heater.  It works, too.  The Z&D does 
not produce much smoke, even at fairly dark roasts.  It does still produce 
"roast smells", but they are not the familiar smells of a roaster without a 
catalyst . . . if you are used to an air roaster (or an Alpenrost) you will 
notice the difference immediately.
The mechanical (screw) stirrer serves the same function as the drum in an 
Alpenrost . . . it "mixes" the beans.  Since the Z&D does not depend on air for 
mixing it gets by with a much smaller heater than in the familiar air roasters 
.. . . the primary heater draws about 400 Watts (the fan and the heater on the 
catalyst brings power consumption up to the rated 785 Watts, still low for a 
home roaster), pretty much all of which goes into the beans (unlike the 
thermally wasteful "fluidized" designs).
The "common flaws" are depressingly familiar . . . there is no heater 
temperature control, there is no bean temperature measurement, and cooling.
Since roast "control" is handled solely as a matter of roast duration (time) 
you get the same problems that any other home roaster suffers with either low 
or variable line voltage . . . the same roast time setting will give a 
different degree of roast depending on where (basic line voltage) or when (time 
of day, if power varies in your area) you do your roasting.  And some users, in 
normally low line voltage areas, will see abnormally long (to the point of 
never completing) roast cycles.  Right up front that explains why some users 
complain that they can't get "dark" roasts with the Z&D . . . with a SOLA CVT 
giving a steady 120V I had no such problems . . . in fact I did a 150 g. (1/3 
lb.) batch of Z&D Sumatra to a dark Full City/Vienna in a 28-29 minute roast 
time . . . sufficient indication that with adequate power the Z&D can roast 
plenty dark.
No bean temperature measurement leaves one guessing for roast endpoint. 
 "Cracks", especially second, are often hard to hear (for whatever reasons) and 
smells are, because of the catalyst, well, "different".  "Color" is at best a 
poor indicator of roast condition, as it varies substantially from variety to 
variety, and it's complicated further by the fact that the beans will continue 
to darken well into the Z&D cooling cycle.
The anemic cooling is a probably unavoidable side effect of the smoke control. 
 There is a limit to the amount of air that can pass through the catalyst 
without cooling it below working temperature . . . that means that there is 
also a limit to the amount of air that can pass through, and cool, the beans. 
 And that amount is too low . . . the beans cool, especially in the very 
important first minute, far too slowly to properly "quench" the roast.  I'm not 
sure what a solution to that would be . . . I'd bypass the catalyst, if I 
could, and put up with the puff of smoke (if there was one) . . . but clearly 
that negates the "no smoke" feature that is part of the Z&D's appeal.  Just 
taking off the lid doesn't answer the problem either . . . without it only the 
(very small) primary heater fan is blowing air across the beans (and even it 
shuts off as soon as the lid is removed . . . you'd have to manually push the 
interlock switch), so you would have to dump the beans into some separate 
cooling mechanism.  Maybe a water spritzer would do it, but that would add a 
"complexity" for the user, where "complexity" is clearly what the designers 
have gone out of their way to avoid.  So poor cooling is something you have to 
anticipate, allow for, and live with (if you can).
All the above begs the bottom line question . . . "can the Z&D produce a 
credible, palatable, roast?"  The brief answer is "yes, it can".  You're never 
going to get the degree of control that some of the more aggressive "moders" on 
this board get from their air roasters, and in general the roasts are going to 
be a bit less "bright" than from the (typically faster) air roasters, but in 
return you get perhaps a bit more "body" . . . a "different" taste profile that 
is not in any way bad.  With decent beans in, and especially if you do not 
roast too dark, you will certainly get a better (and only in part because it's 
fresher) cup than you will from any "store bought" pre-roasted beans.  I'm not 
going to send mine back . . . (and wouldn't anyway . . . I got it at the 
alt.coffee "discount" price, and would think it insufferably rude to return 
something that I got that way, with the full intent of "playing" with it, in a 
clearly not re-sellable condition).  On the other hand, knowing what I now 
know, I wouldn't buy one for my own use . . . I already have a "tricked out" 
Rosto, after all (and an un-modified "backup" Rosto and a HWP).  I am going to 
offer it to friends to try out, though, in the hope of winning a few more 
converts to home roasting.
Deward
Ps . . . a few "afterthoughts" . . .
I did enable the belt tensioner (as discussed on alt.coffee) . . . and think 
it's better with . . . and
It seems that the "economic model" at Z&D is like that of the old Kodak or 
Gillette . . . the money's not in the roaster, it's in the beans.  That said, 
and based only on one bean (so far just their Sumatra . . . they are kindly 
sending (unsolicited) samples of a few others), they have a long way to go to 
match the quality to which the present home-roasting community is accustomed.
It seems altogether possible that the next iteration of the Z&D roaster design 
could be an altogether better machine . . . I hope they heed the comments 
presented here and on alt.coffee.
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2) From: jim gundlach
On Tuesday, January 14, 2003, at 05:45 PM, dewardh wrote:
<Snip>
Anybody else thinking about building your own smoke-eating hood?
Jim Gundlach
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3) From: Ben Treichel
would b e nice, but I'm clue less about how to do that one. I already 
have a vented enclosure.
jim gundlach wrote:
<Snip>
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4) From: Jim Schulman
Thanks for the terrific (and balanced) review
Jim Schulman
On 14 Jan 2003 at 15:45, dewardh wrote:
<Snip>
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5) From: Rich Adams
Yes, after I read that I was thinking of a way to incorporate it into the FR
top since it fits perfectly into a tin can on top of my WB.
Rich Adams


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