Originally Posted by bo_gator
So, with an 18 1/2" WSM how bad are these controllers at driving the temps above the set point
The controller will not turn the fan on if the wsm is at the set temp. Temp spikes are caused by opening the cooker and allowing a big rush of air to the coals no different than opening the dampers.
How do you know how big of a fire to build when using a controller
Is it all trial and error
The fire you build, meaning how full to fill the ring is determined by how long you want the fire to last. For most things, I fill the ring. Unless I'm cooking 300 or higher 12-15 lit briquettes is all you need to start it. You should get 8-12 hours on a full ring depending on all the other factors. If you use a controller, try to catch the temp on the way up. When approaching target temp, shut the bottom dampers and let it settle.
A temp range is fine. Don't kill yourself trying to keep an exact temp of say 250. 235-265 is ok for a desired range of 250, but you will find a wsm will hold temp rock solid without much if any attention.
You will learn by doing. Good info here and on tvwbb forum.