KBQ temperature control

[Rfuilrez]

JGrana If you really want to put the fire board it would be super easy. Just hook the fan output to the control side of a solid state relay and hook that into the draw fan circuit. The only issue is the draw fan is on/off. Not sure how the fire board would do at controlling it.

Also, the way the KBQ works I felt the control method I used works best. I have a HeaterMeter I thought to connect to it, but in the end I would have set it up as an On/Off controller anyhow. PID control works well for a charcoal heat source but not so much the wood fire were using in the KBQ.

Drilling the rivets vets is really not a big deal. It’s only metal. Take it slow and easy!

[Spinaker]

I do have one concern. Does the PID stand up to the heat okay? I would not imagine the control box gets over 55 C, but I have never tested it to see how hot it is when the KBQ is running. When it is cold out, I don't think there will be an issue at all as I am sure the KBQ will keep it warm. But I was just going through the google doc and thinking about this.......

Thoughts?

[Histrix]

I would be concerned about running this modified KBQ on a 95°F sunny August day when running at max temp to roast a chicken or the like. I know my control box is too hot to comfortably touch in those conditions which kinda figures since is is sucking 300°F+ air out of the cook chamber.
I guess we'll find out in 6 or 7 months.

[KBQ]

^^^ Histrix is smart

[Ricardo]

I can only speak from personal experience. The ThermoWorks that came with my KBQ blacks out in just a matter of minutes from heat generated by the unit. I live in FL and use a FireBoard if I’m cooking 2 or more large items. This mod looks awesome, but items from the photos seem susceptible to high temps.

[Rfuilrez]

I understand the concern with regards to heat. I’ll be honest, it wasn’t something I had put any thought into when I did the modification. And, for me personally it’s not a huge problem. If it doesn’t work, or is too hot I’ll fabricate something to fix it. Be that adding a fan, or moving the controller outside the control box. I realize that that it’s probably not the same situation for everyone.

I can’t provide answers for how the PID controller will work when the temperatures are 95* and running a max temp cook. At this point the only thing I can do is provide my current experience. For me, Ill keep the PID controller over the sensing bulb, however I need to make it keep working.

Sometime this week or weekend, I’ll run the KBQ at max temp and put my welding blanket over the control box to see how it runs if the unit is 130* or 150 or something. I’ll monitor the temperature of it with my heater meter. I’ll let you guys know how it goes.

[Rfuilrez]

Spinaker Histrix Ricardo

Well, the weather broke and I finally had some time to torture test the PID controller on my KBQ. I didn't do what would be considered "comprehensive" testing. But I was able to get the KBQ Control box very warm, and the PID controller behaved with no issues. During the testing, it held my set point just fine. The draw fan cycled on and off as would be expected.

I made a box out of 3/8" lexan to surround the control box with. It encased part of the exhaust fan ventilation and mostly trapped it inside. I was able to get the air inside the box at the end of my testing to 98*C (~210 *F). I ran 2 full fire box loads of lump charcoal with the temperature set at 265*. The box was over 55* C (~130*F) (Jaybirds maximum spec) for almost the entire duration, and over 80 *C (!175* F) for at least half of it. It ran for a little over an hour. When charcoal was running out, and the draw fan was on full time, the temperature went over 93* C (~200*F) for about 15min before peaking at 98* (~210* F) and me stopping the test.

Granted, I would expect if you ran it at these temperatures for a long period of time, and often enough you would very much shorten the life of the Jaybird PID controller. That being said, it's about $25 and for me totally worth it. I don't expect here in Chicago that I will see temperatures approaching these INSIDE the control box very often, if at all. Some one living in Arizona or something may want to consider the longevity of the PID controller before deciding to undertake this modification. But, It's not going to die as soon as it hits 55* C one time.

I will updated this thread should I find the PID controller stops working on me.

Here's a photo showing probe positioning and a second showing ~210*