Fan cycling on/off

[Lennard Kong]

question for those of you with either system,
does your fan cycle on for a few seconds and then off when near the target temp or is it just a blip of the fan for a fraction of a second ?

I've got my homebuilt fan done and looking at setting the parameters in the pid I purchased.

 

[Tim Lacy]

I built a DIY ATC that I'll post pictures of tomorrow when I do a couple of butts.

I found that with the default cycle rate of 2 seconds, it tended to overshoot during ramp-up by 25 degrees - the WSM needs more than 2 seconds to react to the fan. At that setting, the fan would blip every two seconds once it had stabilized at 225.

I'm going to increase that cycle rate to 15 seconds and see how it does. I also found that it was a lot more stable with the top vent open about 10-20%.

-T

 

[Tim Lacy]

After much diddling with PID values, I thought I'd just try using the PID controller as a sensitive thermostat. Set Hysterisis (sp?) at 1, temp at 250, and it worked like a champ.

Since I'm attaching the fan to a non-modified lower vent, I used some aluminum foil to create a baffle of sorts to direct the air around and under the ring.

Temp dropped to 249, blower on.
Temp hit 250, blower off.

Couldn't be more pleased. Two butts, one chuck roast and a bunch of chicken, an audience of droolers for the meat pulling (silicon gloves are very cool) and just enough left over for dinner for three the next day. My guests included professional chefs and caterers, and they all gave the thumbs up and said to change nothing (one said add more carolina red to the pulled pork, and I agree).

I'll be doing the same next month, but as much as I can jam on my two WSM.

Costco has shoulder roasts for $1.49 per pound right now...