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Topic: Dual variable transformer Rosto roasting (3 msgs / 65 lines)
1) From: Mike McGinness
Roasted two batches this morning. This is sweet. To recap Rosto fan & heater
have separate line plugs. Using variac for heater, ceiling fan controller -
transformer boosted fan. My max usable fan voltage is 139v under fan load.
It's still barely enough for greens movement at start of batch 1/3#-151gr.
But enough. Need for rocking technique virtually eliminated. I ramped
voltage for same profile - 5min to 350f then 10f per min to 440f. Took
more heater voltage do to greater airflow, as expected. (Oh, ambient temp'
was 35f!) Maintained full throttle fan to about 400f, max  heater voltage
needed 122v to maintain ramp, and then started decreasing fan voltage to
control ramp since bean movement stayed good as moisture lost. By 440f
finish, 14min total time as targeted, fan voltage down to about 120v.
Excellent control you can turn on a dime. Very even roasts. And this is with
my cooler running Rosto at near freezing temperatures! I like it big time.
MM;-) aka Kona Konnaisseur miKe mcKoffee
Dual Variable Transformer Rosto Roasting
Rocky grindin' - Miss Silvia brewin'
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2) From: Ben Treichel
Mike, how do you get to 350 @ 5 minutes, is it like 65 degrees per 
minute, or do you have a know voltage that you set to?
I'm trying to figure out if I need to keep adjusting the voltage up at 
first or ??
Ben
Mike McGinness wrote:
<Snip>
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3) From: Mike McGinness
From: "Ben Treichel" 
<Snip>
Not a set ramp, just going by experience. Uh, haven't been keeping great
roast logs on this ramp. My bad:-( First I always pre-heat the Rosto before
first batch so ramping same as back to back batches. Then begin with voltage
from 105-112v depending on ambient to start. Best I recall 1min approaching
200f, 2min 250f or so, 3min 300f or better, 330f by 4min or I will have
adjusted accordingly. Gotta watch it so it's not going too fast hitting
350f or will ramp beyond too fast. Though now with separate heater & fan
controls can slow or stall at will. Much better control. Separating fan and
running constant 120v gave better control than heater/fan variac'd together.
Don't think it'll be possible to gain any better control of the Rosto.
(except the extreme hacking case of motorized variacs, temp over time
feedback to a computer etc...:-) Maybe some day but I enjoy roasting and
find it relaxing. But when needing to a large number of batches, say for
Christmas, it would be way cool to have total control of the profile and be
able to start it and just walk away for 20minutes! Done cooling roasted just
how you wanted it when you came back.
MM;-) aka Kona Konnaisseur miKe mcKoffee
Dual Variable Transformer Rosto Roasting
Rocky grindin' - Miss Silvia brewin'
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast


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