HomeRoast Digest


Topic: Neon Light Roaster (17 msgs / 402 lines)
1) From: Edmund
This is a multi-part message in MIME format.
Hello Everyone,
I have been looking at the various types of energy sources for coffee
roasters and noticed several using Halogen lights as a source of heat
combined with an electrical heating element. I was wondering if anyone has
used or has such a roaster and could expound on the benefits to using this
type of roaster. Generally most I have read about are gas, electric or
air/heat as the primary methods besides wok, heat gun, toilet bowl :-)  etc.
Regards,
Ed Quesada

2) From: Brett Mason
Is the element safe if chaff builds up on it - could this cause the
glass tube to overheat or crack, etc?
Brett
On 7/26/05, Edmund  wrote:
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-- 
Regards,
Brett Mason
 HomeRoast
      __]_
   _(( )_  Please don't spill the coffee!

3) From: Aaron
Halogens would be a source of heat that is for sure.  Umm One thing I 
remember doing at one time.  I had a halogen lamp that was used for an 
older VHS video recorder and it put out some heat.  Id use this lamp to 
literally melt lead into ingots it was THAT hot.  For the record, lead 
melts at give or take 621 Degrees F.
anyways, yes you probably could use a lamp but the heat would only be on 
the beans on top in direct exposure to the light instead of with a 
heater where the heat would penetrate through... most of the heat from 
these things is radiant heat.  Much like you can stand in front of a 
campfire and feel cozy warm but hold a sheet of plastic or even a piece 
of paper in front of you and it blocks the heat.
A few things.  You FIRST and MUST.. buy a ceramic socket to screw this 
bulb in, if it doesn't have one already, because the intense heat would 
quickly melt / burn / start fire to anything else.
Secondly, make SURE there is a guard around the actual lamp bulb 
itself.  halogen bulbs can get well over 1000 degrees and not only are a 
severe burn hazard if you touch it, but the oils in your skin or 
contaminants can actually 'etch' into the bulb, distort the glass... 
(actually it's a quartz i believe) and cause it to shatter.
third use one of those aluminum shiny 'cone' things around it to reflect 
the heat outward and sort of concentrate it into where you want.  .the 
bulb will be extremely bright too so you will want to avoid looking at 
it really. 
finally, two ways you can vary the heat on this would be either by 
distance from the coffee and / or voltage into the bulb.  Since the bulb 
is purely resistive, playing with the voltage won't hurt it a bit.
This is an interesting method of roasting and I bet it might be doable.
Aaron
Edmund wrote:
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4) From: Jason Molinari
I do believe there is a commercial roaster that uses
halogen bulbs..i can't remember the name.
jason
--- Aaron  wrote:
<Snip>http://sweetmarias.com/maillistinfo.html#personalsettings<Snip>">http://lists.sweetmarias.com/mailman/listinfo/homeroast<Snip>http://sweetmarias.com/maillistinfo.html#personalsettings<Snip>

5) From: miKe mcKoffee
Made by same as used to make Caffe Rosto, Pro 1500. Tom had one to check out 
for awhile.http://www.sweetmarias.com/prod.cafferostoPRO1500.shtmlmiKe mcKoffee
URL to Rosto mods, FrankenFormer, some recipes etc:http://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately the quest for Koffee Nirvana is a solitary path traveled by many. 
To know I must first not know. And in knowing know I know not. Each Personal 
enlightenment found exploring the many divergent foot steps of Those who 
have gone before.
From: "Jason Molinari" 
Sent: Tuesday, July 26, 2005 5:47 PM
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6) From: Jason Molinari
thats the one. I can't believe it can do a 3.3 lb
roast off a standard 20A 110V circuit. It must be
REALLY REALLY well insulated and very efficient.
i'm sucking about 20 amps for my roaster to do a 1lb
roast in 17 minutes, but mine is uninsulated and leaks
heat like a sieve:)
jason
--- miKe mcKoffee  wrote:
<Snip>http://lists.sweetmarias.com/mailman/listinfo/homeroast<Snip>http://sweetmarias.com/maillistinfo.html#personalsettings<Snip>">http://www.sweetmarias.com/prod.cafferostoPRO1500.shtml<Snip>http://lists.sweetmarias.com/mailman/listinfo/homeroast<Snip>http://sweetmarias.com/maillistinfo.html#personalsettings<Snip>

7) From: Matthew Price
On 7/26/05, Jason Molinari  wrote:
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Well, that would be the key to getting all you can out of the standard
residential circuit.  You would probably come out farther ahead by
modding a toaster oven or rotisserie, turning your own elements out of
nichrome or scavenging electric oven elements rather than trying to
steal heat from light bulbs.  The job is to make heat, not visible
light, so the halogens are in a sense wasting some of the energy.
Coffee smoke isn't corrosive that I know of, but it can make a
terrible mess as it condenses.  You should be able to get away with
insulating with refractory without destroying your materials.  Talk
about smoke, though.  As a side benefit, accurate probed temperature
readings should be easier to get as the heat would be distributed much
more evenly with no gradients between a high input element and a high
loss container.
Alchemist John, aren't you doing something like this?  What's your max
batch size?

8) From: Rick Farris
It would seem that way, but yet, the better toaster ovens sold today use
light bulbs for heat.  Yes, halogen lights.  Before claiming that halogens
are more wasteful than nichrome heaters, you might look up the heat
efficiency of both options.
-- Rick

9) From: Alchemist John
I 'just' use a encased nichrome coil, no halogen.  Right now my max 
batch size is about 20 oz, but I am well under 15 amps, probably 
8-10.  I plan on adding another element - maybe I will consider a 
halogen.  It would get light into the roaster.  I almost always like 
multipurpose modifications.
At 19:27 7/26/2005, you wrote:
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John Nanci
AlChemist at large
Zen Roasting , Blending & Espresso pulling by Gestalthttp://www.chocolatealchemy.com/

10) From: STephen niezgoda
My concern with using halogen lamps as a heat source for coffee is the oil.  A drop of oil on the lamp will cause a heat concentration the will actually melt the lamp in a very short time.  This is an issue with halogen headlights, a single fingerprint will ruin a brand new lamp in a few minutes.  I used to work with theatrical lighting and we always wore latex gloves when changing lamps then  wiped them with an alcohol solution just to be sure there were no oils left.
 
Steve N
Rick Farris  wrote:
It would seem that way, but yet, the better toaster ovens sold today use
light bulbs for heat. Yes, halogen lights. Before claiming that halogens
are more wasteful than nichrome heaters, you might look up the heat
efficiency of both options.
-- Rick

11) From: Matthew Price
On 7/27/05, Rick Farris  wrote:
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s
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Don't shoot, we've been through that.  I'm just trying to answer a
call for alternative heat sources with alternative heat sources,
including the pros and cons.  Light bulbs are designed to radiate,
which is what bread needs to toast.  Roasting coffee is much more like
cooking in the sense that beans need to get steady heat in and hold it
while the reactions take place.  toasting==tipping which is what we
want to avoid.
Nichrome is cheap, safe (as much as something drawing 1500W at
hundreds of degrees can be), durable, and easy to work with, hence my
recommendation.  I'll admit that efficiency was a red-herring that I
should have left alone.  The nice thing about building an electric
roaster is that what we want is heat, the thing that thermodynamics
says is most readily made.  If we wanted to compute or communicate
(communicate, bah, definitely not here :) then heat would be a
nuisance.
From the control side, both light bulbs and nichrome won't mind being
cycled over very short periods of time, like clipping AC cycles with a
dimmer.  They won't like being cycled over intermediate time periods
like 30 second runs as it is the time that they are cool that stresses
them the most.
The one catch to working your own elements is that you will have a
difficult time connecting the ends to your electric (non-heating)
wires.  Solder definitely won't work; brazing might work but
mechanical connections like what you will find in a popper are best.
Matt

12) From: Jason Molinari
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I used a ceramic terminal block. Seems to be working
well so far.
jason

13) From: Paul Goelz
At 10:46 AM 7/27/2005, you wrote:
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I believe there is also something to be considered if you intend on using a 
halogen lamp well below the design voltage.  Back when I was designing a 
projector that used a halogen lamp and a triac for voltage control, I found 
that a halogen bulb achieves its long life at very high filament 
temperatures by virtue of the "halogen cycle".  As tungsten evaporates from 
the filament, it is deposited on the inner walls of the bulb.  Above a 
certain bulb wall temperature, the halogen gas in the bulb causes the 
tungsten to be cycled off the bulb walls and re-deposited on the 
filament.  Or at least that is the story I was given by GE.  Supposedly, if 
you run the bulb well below design voltage the halogen cycle stops and the 
filament degrades abnormally quickly.  I seem to recall 80% as a figure to 
stay above, but that is 25 year old memory.
Paul
Paul Goelz
Rochester Hills, MI USA
paul at pgoelz dot com
www.pgoelz.com

14) From: Scott Koue
That is correct.  In theatrical lighting you have this problem because 
most of the time you are running at less than full.  One solution is to 
bring it up to full for a few minutes to get the cycle going and get 
the vaporized tungsten out of the Halogen and back on the filament.  
I'm not sure how much this helps but it is a standard procedure.  As a 
extra trivia bit about "halogen" bulbs is that they are also called 
Quartz bulbs because the "glass" in them is actually cast quartz.  The 
surface temperature of your normal incandescent bulb is about 200 
degrees but a "halogen" bulbs surface temperature is around 2,000 
degrees, way over the melting point of glass.
SK
On Jul 27, 2005, at 8:50 AM, Paul Goelz wrote:
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15) From: Tom & Maria - Sweet Maria's Coffee
Yes - the Unimax used halogen heating elements. It's a good idea but 
you need to keep chaff away from them, or at least keep most chaff 
away - a little won't hurt.
Tom
-- 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                   "Great coffee comes from tiny roasters"
            Sweet Maria's Home Coffee Roasting  -  Tom & Maria
                      http://www.sweetmarias.com                Thompson Owen george
     Sweet Maria's Coffee - 1115 21st Street, Oakland, CA 94607 - USA
             phone/fax: 888 876 5917 - tom

16) From: javafool
Interesting you mentioned that Tom. The first roaster I bought from you,
while you were in Ohio and I lived in Indiana, was my Unimax 2000. I didn't
have quite enough of a given Kona last night to use my Hottop, so I roasted
what I had left in the Unimax. It still roasts exceptionally well. I just
have to stop the roast really early compared to the HT because the cooling
is so slow.
I wonder how many of these are still in use????
Terry

17) From: Paul Goelz
At 02:49 AM 7/27/2005, you wrote:
<Snip>
Assuming there aren't any light leaks, the efficiency of either heat 
source should be exactly the same.  All energy consumed by the 
heating device is radiated as some form of energy.  As long as it 
does not leave the chamber, all energy radiated is absorbed by the 
chamber and contents and re-radiated as heat.
Paul
Paul Goelz
Rochester Hills, MI
paul at pgoelz dot comhttp://www.pgoelz.com


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