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Topic: Roasting with a Variac (6 msgs / 122 lines)
1) From: Ben Treichel
Ok Guys,
What's the best way to tie a variac into a roaster (FR+). I'm thinking 
about taking the machine apart and putting the variac on the heater 
coils only. If I remember the fan is rectified to dc, so a voltage drop 
will slow down the fan. That seems counterproductive since I want to 
slow the roast.
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2) From: Jim Schulman
Hi Ben,
I just plug my FR into it, slowing down both the 
fan and reducing the heat. This method has one 
advantage and one drawback over tieing it to the 
heat alone.
The advantage is that the temperature and airflow 
reduce and increase together, this virtually 
ensures no scorching (i.e. plenty of agitation 
when the temperature is high), and no rapid cool 
off (less air when the temperature is dropped). 
Almost all roasting authorities agree if the bean 
temperature drops during a roast, quality is 
compromised; and this arrangement makes this less 
The disadvantage is that at low settings, the 
beans cease to move properly early in the roast. 
So it's hard to slow down the roast prior to the 
first crack. Mike gets round this by rocking his 
Rosto. I'm lazier and the FR has less metal to 
bean contact, so I let the roaster run at 85 volts 
for 90 seconds. The beans don't move, but since 
the air temperature is about 280F, they don't 
scorch either. They just dry out, and even up when 
I'm doing a blend. After that, my normal range of 
control voltages, 95 to 125, works just fine.
So my two cents is to save yourself the bother and 
just plug it in.
On 23 Nov 2002 at 15:23, Ben Treichel wrote:
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3) From: John Abbott
Or at least try it that way first. You might be impressed with the results.

4) From: Ben Treichel
John Abbott wrote:
That makes sense.

5) From: Mike McGinness
From: "Ben Treichel" 
I've been roasting with a variac to control the Caffe' Rosto for some time
now. Just direct plugged into the variac. I've been strongly considering
splitting the AC into the Rosto for independent heater and fan control.
Ideally both would be controllable. Considered a second variac but leaning
towards simply using a rheostat for fan control. Draw back wouldn't be able
to 'boost' the fan for faster cooling. (currently I usually up the voltage
to 125v during cooling cycle, especially useful during hotter months.) Could
quickly switch the fan plug to the variac during cooling, but what a hassle!
I believe I'd have better and faster ramp control with independent fan &
heater control. Just haven't gotten around to modifying either of my Rostos
Variable Variac Rockin' Rosto Roasting
Miss Silvia brewin'
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6) From: Rick Farris
Mike wrote:
How about a ganged pair of spdt switches?
-- Rick
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