Take a look at this stokerlog graph. At 8:45 I fired up the cooker,
and then went to turn the stoker and stoker log on. By the time stoker
booted up a minute later, my temp was a little over 100, and I had set a
target temp of 250 for the entire duration. You can see the initial
but slight overshoot in the graph, as the cooker came up to target temp
very quickly.
(Story continued after the graph)
By the way, the "cooker" in this case ...
...
is the main oven my Gemini electric double oven range. Pit Sensor was
placed on the middle of the middle rack. I set the oven temperature to
250. Now, a maytag gemini oven is NOT a deluxe piece of cooking equipment,
and mine IS almost 10 years old, but I would say it is of "average or
slightly above average" quality.
So, some may be suprised to see the oscillation of temperature in the
sequence above. It settled in at about 240 on the low end and 285 on the
high end. (This is a few degrees higher on the high end than I expected.
With both a bottom and top heating element, my oven seems to heat very
quickly, but is not very well insulated.)
Here are some observations:
It was funny to me that, although the stoker fan never came on (except at
the beginning when it thought it was heating my oven) my oven DOES click when
the heating element cycles. My laptop and myself were within earshot of the oven
so I could hear it cycle, and then immediately see the result on stoker log ...
just like i do while watching the blue light.
At 10 am, I opened the "lid" (oven door) for 10 seconds to "put the meat on"
(stare at the pit sensor). Of course I wanted to see how an electric oven
handles the overshoot that we see when we do this with the stoker and a WSM.
Sure enough, my dumb electric oven overshot the target temp OUTSIDE the bounds
it had been oscillating within, and nipped 300. Bear in mind, I had that door
open for MAYBE 10 seconds. Since the oven is not an organic fire, the overshoot
ended there, and it quickly returned to the 'normal' oscillation pattern the next
cycle through. With a real fire, we often see this spike last longer, sometimes
much longer, because you can not turn off a charcoal fire like you can the
heating element in an oven. However, the oscillation in a stoker/WSM cook is
SO MUCH smaller, that the overall effect of this temp spike is less than the standard
oscillation of an electric oven.
I decided to stop the test after 2 hours*, because my house was getting hot and
I think my point was illustrated. The stoker's cycle frequency seems to be MUCH higher
than my electric oven. Therefore, given no changes in environment, my stoker
with WSM are FAR MORE stable than my electric oven. Generally, the stoker responds
very quickly when it needs to. By minimizing the times we change the environment
during a cook, we can help the stoker and WSM keep this consistency. But more
importantly by having an understanding of how a PID based temperature controller works,
we can appreciate just how stable the stoker is.
I often see people talke about "crazy graphs" and "wild swings". I hope now there is
a little more perspective on how wild those swings really are.
*PS, I actually decided to crank the temp to 300 after two hours, just to see what
overshoot might happen. I frequently see people ramping up the temperature during a
'real' stoker cook, and then being alarmed at how much that it over shot, so I thought
I would replicate that here before shutting down.
Here is that graph ... overshot by 30 degrees.
and then went to turn the stoker and stoker log on. By the time stoker
booted up a minute later, my temp was a little over 100, and I had set a
target temp of 250 for the entire duration. You can see the initial
but slight overshoot in the graph, as the cooker came up to target temp
very quickly.
(Story continued after the graph)
By the way, the "cooker" in this case ...
...
is the main oven my Gemini electric double oven range. Pit Sensor was
placed on the middle of the middle rack. I set the oven temperature to
250. Now, a maytag gemini oven is NOT a deluxe piece of cooking equipment,
and mine IS almost 10 years old, but I would say it is of "average or
slightly above average" quality.
So, some may be suprised to see the oscillation of temperature in the
sequence above. It settled in at about 240 on the low end and 285 on the
high end. (This is a few degrees higher on the high end than I expected.
With both a bottom and top heating element, my oven seems to heat very
quickly, but is not very well insulated.)
Here are some observations:
It was funny to me that, although the stoker fan never came on (except at
the beginning when it thought it was heating my oven) my oven DOES click when
the heating element cycles. My laptop and myself were within earshot of the oven
so I could hear it cycle, and then immediately see the result on stoker log ...
just like i do while watching the blue light.
At 10 am, I opened the "lid" (oven door) for 10 seconds to "put the meat on"
(stare at the pit sensor). Of course I wanted to see how an electric oven
handles the overshoot that we see when we do this with the stoker and a WSM.
Sure enough, my dumb electric oven overshot the target temp OUTSIDE the bounds
it had been oscillating within, and nipped 300. Bear in mind, I had that door
open for MAYBE 10 seconds. Since the oven is not an organic fire, the overshoot
ended there, and it quickly returned to the 'normal' oscillation pattern the next
cycle through. With a real fire, we often see this spike last longer, sometimes
much longer, because you can not turn off a charcoal fire like you can the
heating element in an oven. However, the oscillation in a stoker/WSM cook is
SO MUCH smaller, that the overall effect of this temp spike is less than the standard
oscillation of an electric oven.
I decided to stop the test after 2 hours*, because my house was getting hot and
I think my point was illustrated. The stoker's cycle frequency seems to be MUCH higher
than my electric oven. Therefore, given no changes in environment, my stoker
with WSM are FAR MORE stable than my electric oven. Generally, the stoker responds
very quickly when it needs to. By minimizing the times we change the environment
during a cook, we can help the stoker and WSM keep this consistency. But more
importantly by having an understanding of how a PID based temperature controller works,
we can appreciate just how stable the stoker is.
I often see people talke about "crazy graphs" and "wild swings". I hope now there is
a little more perspective on how wild those swings really are.
*PS, I actually decided to crank the temp to 300 after two hours, just to see what
overshoot might happen. I frequently see people ramping up the temperature during a
'real' stoker cook, and then being alarmed at how much that it over shot, so I thought
I would replicate that here before shutting down.
Here is that graph ... overshot by 30 degrees.
