I'm in geek heaven here. I just built a HeaterMeter for pit control and jacked it into my 18.5" wsm. I've got a brisket flat on there and am part way through the cook. My wsm (and my uds, and mini wsm) are very easy to control, so this pit controller is just a toy to play with.
So far it's interesting. I'm going hot and fast on this, and had a welding blanket wrapped around the wsm to start. You can see the temp was above setpoint until about 12:20 pm, at which point I removed the blanket. I wanted to see the blower come on.
Now that the fire needs to put out more heat to overcome the heat loss through the sides, the controller is doing a pretty good job of holding setpoint. I wrapped the flat in butcher paper at about 12:45, you can see a spike there. Oh, as I type this another temp spike occurred. Fun stuff!
I'm written a script that uploads an image of the temp graph
every 5 minutes. It doesn't auto refresh, so if anybody is interested in watching the progress they should hit refresh in their browser to get an updated image.