Help figuring out what's wrong - won't burn all the fuel


 
Well, yes and no... Your output really isnt 5" after you put the bge vent on it... and you can push a lot of air through a 1" pipe with the right pressure behind it. That said, if the input tube were larger that would allow more air to flow and it would flow at a lower velocity. Being a DIY pit you're just gonna have to fiddle with it to dial it in...
Can I ask what is the range of cook temps you desire to achieve? Typically smokers are all about low and slow, which it seems you should be able to achieve with the rig you've got now. If you want to cook higher you might want to look at scaling your fire to your cook. For instance, when I do low and slow on my akorn I only light a small pile of lump coal, if I am cooking pizza or steak I light a big old pile... You may want to adopt this sort of strategy when building your fires for low and slow VS medium or high heat cooks.
 
I was dreaming of getting a range like a BGE. 200-1000F - depending on how it's set up. But realistically I was hoping for 200-500 to 600F range. I was also hoping for a load of fuel to burn 20-24 hours since I should be able to really put a lot of fuel in the thing. It has a 22.5" diameter almost all the way to the bottom of the barrel. There's a lot of room for a lot of fuel.

Maybe those temps and length of cooking time is just not possible. I'm taking the temperature at grill/grate level. This is at the top of the base portion of the smoker. I believe it's sealed up really well - no leaking.
 
1000F? WOW!!!! What the hell are you going to cook at 1000F? Man, I was way off at estimating your expectations! LOL
You're gonna need a whole lot more than a chimney of briquettes to achieve 1000F, if there is even a reason for that? I had my fauxmado up over 900F the other day (with the 6.7 CFM blower in my RD3) and totally melted my nomex gasket, was not good! Had fun with the flash of fire opening the lid though! LOL
The only thing I can think of that would cook that hot is pizza, and in most cases with the fire below the pizza stone running temps that high will make the stone too hot so the crust burns before the toppings cook...
That said, load in a big ol' pile of lump coal and set the blower to 100% and see what she will do! Scaling your fire is gonna be a must if you want to be able to achieve that range of temps. Just be careful opening the lid when temps are that high, you can get a nice flash of fire....
 
I don't want to really cook at that high temp (I think Pizza would be the only thing near that high, or maybe steaks like Ruth's Chris steakhouse). It's just that I wanted to make something that worked as good as the BGE...
 
a BGE has an inch thick ceramic insulation, a thin walled barrel smoker is gonna bleed heat like nobodies business....
 
BTW, now that you're running at a reasonable low and slow temp I see that you will be able to achieve that with your setup, no problem, but your PID settings appear to be way off... Could be just because you brought her down low from high though, let her settle out and see how she does...
 
I would suggest you go back to the default PID settings and see how she rolls... or pick a reasonable setpoint and let the pit oscillate a few cycles and then go to Config/Status/SystemLog and try the PID settings suggest on the last line that says "Ziegler". Those would be the suggested auto tune settings, which Bryan says are bad, but seem to work reasonable enough for me... it might give you a better idea where the PID settings need to be, P of 7 seems high to me, and your I seems like it should be smaller too... You can always refer to the HM WIKI and read up on PID tuning.... You've got a one of a kind beast here, so no sense trying to grab settings from a BGE or other setup, you are on your own path with this one....
 
I changed PID to 4, .02, 5. I opened up the exhaust event a little more.
There is a lot more force of air coming out of the exhaust vs. the micro damper.
 
A blower can overcome a bottleneck like a smaller input tube or closed top vent much better, it has more pressure behind it... Generally speaking, when you have a blower running you want to run the top vent tighter, because the blower can overcome the small opening and force air out when needed, then when it slows down the tight top vent tamps down overshoot.
Watching your pit I see after the high temp setting you lower the setpoint to 275 and the blower is going like crazy while the pit is holding like 235F, then you change the setpoint to 225F and the blower shuts off, the temp blooms to about 240F and then starts to dip. This tells me you have about enough coals burning to maintain about 225F right now. If you want a higher temp you need more coals burning.....
 
the fuel is burned out. It looks to have lasted til about 10:15pm. That's a plus. It wouldn't have happened with the micro damper fan.
I'll try some hardwood charcoal tomorrow and see what happens.
 
So that's progress... I knew a blower would be able to push enough air to do low and slow and burn out your fuel. Now lets see how it does when you light a huge load of lump coal, I think you will probably be able to achieve your more reasonable goal of 400-500F. 1000F in a non-insulated steel grill would be down right dangerous, imagine removing a 1000F metal lid and holding it in your hand... You'd need some asbestos gloves for that! LOL
 
RKHanso said:
It appears that the standard HM blower will only get my smoker up to about 330 with the 5" exhaust wide open (see 7:50-8:10pm).
Click to expand...

RKHanso said:
Here's a snapshot of my test today, with no exhaust vent....just a wide open 5" hole.

MD%20but%20no%20BGE%20vent.PNG
Click to expand...


So the fan and blowers have more or less the same performance.


RKHanso said:
I made a homemade smoker and have tried a couple test runs with it. It doesn't seem to burn all the fuel before the temperature drops off. This has happened each of the 3 test runs.

I'm using a Micro-Damper and a BGE top vent with just the little slots open.
Click to expand...


RKHanso said:
the fuel is burned out. It looks to have lasted til about 10:15pm. That's a plus. It wouldn't have happened with the micro damper fan.
Click to expand...

How can you be so certain? You haven't been testing apples to apples here. You need to run the MicroDamper with your vent swung open to even be able to compare. The brief times you have tested apples to apples the performance was practically the same.
 
I'm doing a test with hardwood now. The only kind my local store had was Royal Oak Hardwood. I'm only burning one chimney's starter's worth. The exhaust vent is about 1/2 way open right now. I'm using the standard 50mm HM Blower. PID = 4, .02, 5
http://heat-makarios.ddns.net/
SteveCK said:
So the fan and blowers have more or less the same performance.
How can you be so certain? You haven't been testing apples to apples here. You need to run the MicroDamper with your vent swung open to even be able to compare. The brief times you have tested apples to apples the performance was practically the same.
Click to expand...
I did run the micro-damper previously with the exhaust vent completely removed. It struggled to keep 300F and could not get up to 325F. The blower with no exhaust vent could get up a little higher and keep the fuel burning until it was used up. The Micro-Damper could not. See post #16 for the info on that.
 
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At 4:19pm, I removed the BGE exhaust vent as it appeared the smoker would not get above 255F.
Waiting to see what happens now.
 
When I drop the set temperature and the blower stops, the temperature seems to spike up a bit, before dropping. Is this because I have too much air flow and it's cooling off the smoker? Maybe I should put the exhaust vent on again and choke it down quite a bit and see what happens?
 
At 4:36pm I put the BGE exhaust vent back on and opened only the daisy wheel vent so the first hole is 1/2 way open (the rest are in a increasingly SMALLER opening as you go around). That blower sure can push the air through the smoker. There's a good stream of air pressure coming out the exhaust vent.
http://heat-makarios.ddns.net/
Thursday%20test.PNG
 
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at 5:00pm I opened the daisy-wheel portion of the BGE vent completely, since the temp wouldn't hold at 240F
 
IDK what size starter chimney you have, but you might need a bigger load of coals to hit higher temps. Keep in mind, with a tight pit like you have and using lump coal, when your cook is done close off the vents and the coals should go out. Next cook you can just shake the ash off and use what is left of the coals... so don't be shy about loading it up for high heat cooks, it wont go to waste.
 
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