PID fan controller for the drum

ol' smokey · Oct 25, 2009

I’ve been meaning to try this for awhile now. Already had the PID controller built and was using it to control temps in my Bradley smoker. Don’t laugh at the cardboard box, this is just an experiment.
The idea is to use my PID temperature controller to operate a small 4 CFM fan to feed air into the drum as needed to control the temps. At this point the only thing I had to buy was the $16 4 CFM AC fan.

Parts: 1 cardboard box, 1 4 CFM fan with power supply

Cut a round hole in the box for the fan to blow through. Then mounted it using a couple of screws.

On the other end I cut a small hole so the 1/2 nipple wound fit in and sealed the box.

Here's the controller with the power supply plugged in.

Here we go. I have the sensor attached on the side here but later moved it to a vent hole on the lid so it would read more like the analog temp gage already mounted there, the RWB one is new and is being compared to the other two. The box mounted on an existing 1/2 nipple. Notice the air intake on the left is open, I'm getting it up to temp and will later close this completely.

After coming up to temp I set the PID at 220°. After the drum settled down it was holding between 216° and 226°. I cranked it up to 230° and the range was 226° and 236°. Set it at 225° and put a Butt in, no sense in wasting the fuel. I should have tested at higher temps also but didn't, next time.

Here's the butt at 190°. It took 12 hours and I had to stir the coals one time. FTC it and went to bed.

This morning I pulled it.

All in all the experiment was a complete sucess. I might try a larger CFM fan next time or mabey 2 of the 4 CFM but for sure a new watertight box is in order as well as a 1/8" connector for the thermocouples as the one on the Bradley is permanant.

Thanks for looking

davenh · Oct 25, 2009

Nice job on the control and using what you have! I like the idea of making a guru style temp control.

I'm doing similar thing for my gravity feed smoker. Going to use DC stuff and make it run off 12v, power it with a 12v, 1A wall PS (run on battery if needed). Auber has some cheap controller parts and digikey has small DC blowers.

Here's a few links to the parts I'm going to go with.

http://www.auberins.com/index.php?ma...b812c630e83629

http://www.auberins.com/index.php?ma...b812c630e83629

http://search.digikey.com/scripts/Dk...me=603-1118-ND

pandemonium · Oct 25, 2009

Cool thing but i like the easy no frills way, that seems a bit much to me, but since you already had the parts why not?
I just know i have spent enough on my uds already

rodc · Oct 25, 2009

That's a nice piece of work.

You should check Geek With Fire's site (he's on the SMF forum) - he's an artist at this kind of thing.

http://www.geekwithfire.com/Home/tabid/36/Default.aspx

mrh · Oct 26, 2009

Joe,

What a great idea!!! I hve a PID for my Bradley too, it is all self contained so all I need to do is get a fan and adapt it to a nipple on the drum poke in the TC and it should work.

Thanks for the Idea and there will be points for you!
Mark

lennyk · Oct 27, 2009

I put together one recently for my stump clone also.

A good fan to use a computer cpu fan, they are usually 12v and quite powerful. They come with a 3 wire connector but only need 2, you can figure out which two easily by trial and error.

I used a pvc electrical box

geek with fire · Oct 27, 2009

Thank you sir.

That's a really nice setup. I think though, for the drum, you will need something to restrict the draw when the fan isn't running. I built a box with 2 pipes on the end for my drum. The fan gently pulls air in, but due to the length of pipe I use, when the fan isn't running, the system chokes (which is what you want)

lennyk · Oct 28, 2009

yes, I have my valve closed a little more than I would have if it was running without the pid/fan.

The ideal way is to put in some form of flapper door, havent really given it much though though.

ryan in louisville · Mar 2, 2010

Josh,

I am thinking of doing this on an offset fire box but it seems as though the heat from the box would melt the PVC tubing. Have you had any issues with this?

I came up with the idea of making a phonelic adapter (female thread on both ends) as a way to keep the heat from being transferred but every one that sells phonelic in sizes big enough to use as an adapter REALLY likes their product, man is that stuff expensive.

Thanks,

Ryan

geek with fire · Mar 15, 2010

Sorry Ryan, I haven't been around in a while. The tube you showed above only gets used on the drum, as the temperatures past the pipe nipple don't get hot enough to melt the PVC. On the horizontal (a CG), I use a different rig. My "temporary" extender consists of a $1.50 paint can I bought at Lowe's; cut the bottom out of it to make it a tube. Redneck, but works well. Then I bolted on my control rig to that. The CG requires more adjustments than the drum, so this box has a servo to open and close the damper, as well as a fan to stoke the fire. Here are illustrations of the setup. If you click the image, it will take you to my web site which has a video of it running:

rbranstner · Mar 15, 2010

How much roughly would you say it costs to get a whole PID set up? I can get fans at work for free as we throw old equipment away but the whole control unit is what I have no idea about. I am looking to put on on my UDS

deltadude · Mar 15, 2010

Geek with Fire, where did you get the damper actuator and how much was it? thanks..

geek with fire · Mar 15, 2010

Mine got really expensive because I went overboard. Very adjustable outputs and very accurate thermocouples. All of my stuff uses devices from a company called Phidgets. They are USB controllers for temperature, motor control, etc. For bare bones, you're probably looking at a couple hundred bucks. Which leads me to my next point: The BBQ GURU works better for the money on a drum. My system still works better on a leaky smoker like the chargriller because of the finite adjustments I can make. The drum doesn't need that. A few puffs every now and then (if you leave the lid closed!) and it will run fine. The only limitation to the Guru is that you can only use 2 probes: one for food and one for pit.

The actuator is just an RF Servo connected to a Phidgets Servo controller.

boondoggle9 · Mar 15, 2010

Did you finish this project? Are these all the specialty electrical parts you required? I was looking through this thread and checked out the links and this looked very interesting and "do-able". Thanks for any insight and pics you might have.

ryan in louisville · Mar 18, 2010

Josh,

Would you list all the parts required to do a 4 meat probes/1 smoker probe build in Phidgets? I am planning on doing this in VEE, HOPEFULLY

.

Where did you get your probes? I am looking at k-type thermocouples and Maverick style probes but am up oin the air right now.

BTW, does anyone know what the specs are on Maverick probes? thermocouple type, etc?

Thanks,

Ryan

geek with fire · Mar 18, 2010

You can do it a couple of different ways:
1.) (Cheaper) Use the Phidgets 8/8/8 and connected standard Maverick Probes (which are thermistors probes). Thermistors return a resistance based on a temperature. Unfortunately, it isn't linear, so you you will have to create some sort of cross reference for each probe. But, the 8/8/8 would let you connect up to 8 of these probes. Then you would need at least a servo controller, to actuate a servo controlled damper, or motor controller to operate a fan. Both can be found on the phidgets page (and can be bought domestic through www.trossenrobotics.com)

2.) (More accurate...less headache...but more expensive) Buy Phidgets thermocouple controllers for each probe you want. Each has it's own serial number, uses USB and easily translates into temperature. Then buy K-type thermocouples from anywhere, but I get mine through Thermoworks (the makers of the thermapen). Then, again, you will need either a servo controller or a motor controller to feed air intake.

Price it out, then price out the BBQGuru or the Stoker. I have a Guru and like it. I still use my custom rig, but only on the horizontal. When using the drum, I always use the Guru.

ryan in louisville · Mar 19, 2010

That's what I was afraid of, thought I was missing something on having to buy 5 cards for 5 temps.

I suppose I'm going to do my cheap and dirty way short term: fan w/ PID controller. I'll look at doing my VEE based controller down the road. I just got the OK from SWMBO to buy the smoker and luckily the PID controller is cheap so I can sneak that one in.

Thanks, again,

Ryan

triple d bbq · Dec 19, 2012

So what setting did you go with? P? I? D? Auto limit 1? Hysteria? etc. I sure would appreciate knowing where to start.

PID fan controller for the drum

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