No, we're closer to you guys in Richardson. The BGE didn't get hailed on as it went just north of us on Monday but it looked like it was going to be a big one. I never even thought about BGEs getting hail damage but with what Wylie got, I'm sure some were injured. If you're in my neck of the woods and would like a demo, let me know. Small world.
Whomper Damper
- Thread starter JayC
- Start date
No, we're closer to you guys in Richardson. The BGE didn't get hailed on as it went just north of us on Monday but it looked like it was going to be a big one. I never even thought about BGEs getting hail damage but with what Wylie got, I'm sure some were injured. If you're in my neck of the woods and would like a demo, let me know. Small world.
Steve, the're in the first post and I haven't messed with them since calculating them based on my prototype.
P=30
I=.0227
D=95
What I find affects this thing more is how open/closed the chimney is at this point. I keep the stock BGE chimney about 2/3 of the way open and then make one or two small bumps from there to get good steady state usually. What I just did is replace it with a SmokeWare chimney to help in the rain (and it doesn't hurt that it looks better and replaces the cap and chimney) and find that just about a pinky finger opening in that works well. It also really settled out some of the spikes IMHO compared to stock.
Thanks for the compliment on the table. I'm about to start work on another one that will have a sink and kegerator to round out the outdoor kitchen. When it's done, both get custom tops concrete tops so I'm really looking forward to that.
P=30
I=.0227
D=95
What I find affects this thing more is how open/closed the chimney is at this point. I keep the stock BGE chimney about 2/3 of the way open and then make one or two small bumps from there to get good steady state usually. What I just did is replace it with a SmokeWare chimney to help in the rain (and it doesn't hurt that it looks better and replaces the cap and chimney) and find that just about a pinky finger opening in that works well. It also really settled out some of the spikes IMHO compared to stock.
Thanks for the compliment on the table. I'm about to start work on another one that will have a sink and kegerator to round out the outdoor kitchen. When it's done, both get custom tops concrete tops so I'm really looking forward to that.
Benjamin Thibault
TVWBB Member
30 for a P seems way too high. It would mean that at 3* under set point puts it basically wide open... At that point you're basically on/off with it.
Though if you're holding temperatures good who am I to say it's wrong.
Though if you're holding temperatures good who am I to say it's wrong.
That's the only way I could get this thing to work right. I'd initially gone off of the settings that I had for another damper and kept changing them little bits at a time and was seeing massive oscillations so I went through the PID tuning methods (made an Excel Spreadsheet w/ the formulas to start calculating stuff from scratch).
Of course, then the numbers were so different from what everyone else was doing on their dampers and I thought I'd calculated it incorrectly but it seems to work great. I think part of what is going on with this is that my system responds differently than the other systems because it isn't completely sealed (nor should it be IMHO). There is a certain amount of air that can pass through the damper even when it's closed because of the annulus around the valve and the valve body so that the thing spins freely and doesn't bind as the tolerance on the 3D printed valve isn't great even after I touched it up a lot with files. I think it's important that it be able to breathe a little even when 100% closed so that the coals don't snuff out and you can have at least some natural convection internally. The only reason to require a sealed system is if it's running away and it can't be pulled back down (again, IHMO). That also means that this system is slow to respond but that's not a bad deal either if it's hanging around where it needs to be. I don't see much on/off behavior for slow and low. It remains partially open most of the time and just moves a little bit in either direction unless it's either really windy or the coals are getting toward the end. Typically, I'll let it burn out after I take the meat off just to see how much longer it could have gone. 18-20 hours is about all she's got but that's all I need anyway. Where I do see it oscillating on/off is at higher temps but we're talking about +/- 5 degrees of setpoint. At 400ish, that's essentially +/-1% and I know from using the HM with a conventional oven that the BGE is working about the same way in that case. I don't remember enough about control theory from engineering school to know what the values should be but do like the graphs I'm seeing so that works for me.
Benjamin Thibault
TVWBB Member
Yeah. If it works it works. Don't mess with it. Just seems really high is all. Lol