damper control


 
Yeah Dave has sent me a servo-controlled damper to play with, but I have been too busy with projects to attach it to my grill and test it. I'll probably be integrating a servo or fan control into the base code, but not both because I don't think there's another free PWM pin and modifies the configuration structure.
 
I still have it sitting on my desk. I ran out of solderless breadboards, and let's face it, when you've got 3 projects on breadboard you're at your limit for dividing your time between projects. Good news is that I've finished my flowmeter and finished the design for the mutilpexed display portion of my fermentation controller so I should be getting to it shortly. I'm also tired of everyone laughing when I duct tape the blower to my big green egg for every cook now that my cardboard prototype fan bracket has failed catastrophically.
 
I also have a Big Green Egg like Bryan. My brother and I made a stainless steel fan adapter based on Bryan's original design that I found here
fanflat.png


We made 2 modifications.

First was to add a damper. It is just a flap with a nut epoxied on the end for some weight. The paperclip goes through a bar straw that is attached to the top of the flap. I like this better than a servo since there is less to break. The main thing to look at is to see how much weight you need to add to the damper to keep it closed when the fan is not on but light enough that the fan can open the damper when it is on.

Second was a hole in the bottom of the mounting plate to accomidate the plastic fan clip.

The main design flaw right now is that I also have a nest for my Big Green Egg like Bryan and it is hard to get the adapter plate on and off with the nest. If you don't have the nest it is easy to slide on and off. But if you do you just have to fold the attachement plate a little bit to get it installed on the egg.

Here are some pictures of the fan assembly and damper.
https://plus.google.com/photos/111284386457647670914/albums/5861929296839301617
 
fan case/adapter

Thanks a lot for posting your pictures of your fan adapter. I am not very good at fabricating things out of metal (or at least I have not done it before). I did make a prototype case for the fan out of cardboard based on Bryan's plans. I would still need some sort of adapter to slide into my large BGE though right? Is there anything commercial I could buy to use with the stock fan from the parts list that is a case for the fan and will attach to the BGE lower vent?

I am not sure how you would get the stainless steel to attach, is it welded or could you use JB weld? I am not even sure how to bend it, lol. Could it be done out of tin recycled from cans etc and soldered?

Perhaps too many questions for one post, sorry!

Thanks a lot for any help you can provide.

Jason
 
I didn't have much luck with trying to braze the metal together. JB weld didn't work either because there wasn't enough overlap in the pieces to give it a good area to hold on to.

For an "adapter" to the BGE, I just used a flat piece of cardboard cut to the size of the sliding vent channel and then cut a square hole in the middle for the fan to go through. You're going to want to use something stiffer than cereal box cardboard though or else it bends and falls out under the weight of the blower.
 
Thanks for the ideas guys! I had not seen the post of Jason J's, I am going to take a look at that method too.
 
Hi all,

Based on what others have done I came up with this for my BGE. The metal is a tuna can and another tin can fastened together with those butterfly bolts.

Here is a screenshot of my first burn with it, I had it set for 275, do you think I need to have a damper on the bottom vent too? I had the top vent of the BGE completely off until it was at 275, perhaps I should have had it on the entire time? I guess too much airflow is coming in the bottom vent?

The black fabric on the right is a soldering pad that I used to try to make a bit better of a seal. Any thoughts and recommendations are greatly appreciated! Right now the temp has come down to 296; am I just being too impatient? lol

temp.png

20130412-0068-0003.jpg


ps. sorry maybe I should have made a new thread for this

Jason
 
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When you say the top vent was complete off, do you mean "not installed at all" or "completely closed off"? If you had the top wide open it will overshoot like a mofo and may not ever come down at all. For 225F I keep the top star bit just slightly open. Like just enough to poke a toothpick into it and I get a curve like this. (No damper on the bottom, just the standard cardboard mockup)


That's probably my best example. If the fan slows down too early, the temperature stops climbing almost immediately and starts dropping. On your graph I see the fan cut out about 255F and 5 minutes later passed the setpoint. There's just way too much airflow getting in there, probably being pulled in by the hot air going out the top.
 
Bryan Mayland said:
When you say the top vent was complete off, do you mean "not installed at all" or "completely closed off"? If you had the top wide open it will overshoot like a mofo and may not ever come down at all. For 225F I keep the top star bit just slightly open. Like just enough to poke a toothpick into it and I get a curve like this. (No damper on the bottom, just the standard cardboard mockup)

That's probably my best example. If the fan slows down too early, the temperature stops climbing almost immediately and starts dropping. On your graph I see the fan cut out about 255F and 5 minutes later passed the setpoint. There's just way too much airflow getting in there, probably being pulled in by the hot air going out the top.
Click to expand...

Thanks Bryan, sorry if I was not clear. I meant I did not have it installed at all. That is probably why I overshot a ton then! I will try again tomorrow being a bit more cautious :) I will leave the star open like you do. Thanks a lot for your guidance!

Jason
 
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Bryan Mayland said:
When you say the top vent was complete off, do you mean "not installed at all" or "completely closed off"? If you had the top wide open it will overshoot like a mofo and may not ever come down at all. For 225F I keep the top star bit just slightly open. Like just enough to poke a toothpick into it and I get a curve like this.
Click to expand...

My last cook, I ran into this exact issue with my WSM. Bottom vents closed (except for the one with the fan), top vent "mostly" closed. Still had a couple of times where it started to get away from me, but only 20 or so degrees above my setpoint. Ended up covering the "lamp grommet" probe hole with foil as well. The ol' girl has been around a bit, so she might be a little leakier than your average WSM. :-)
 
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