250L build - now a 35? gallon build

[munxcub]

What kind of treatment should I give the cook rack. It's rusty right now and I was going to sandblast it clean. Is oiling/seasoning it sufficient? 

I am planning to give everything one more burning out tomorrow, as I've added the RF plate and some other things since burning the junk out of the tank. Can I burn it in nice and hot for an hour or two, drop the temp down, spray it all with some kind of cooking oil, and run it at ~250 for another hour or two and be good to go? 

 

[munxcub]

Got the handles and door stop on. Cook rack is mostly cleaned up.

20130823_211929.jpg

• munxcub
• Aug 24, 2013

 

[munxcub]

Brought it home and fired it up for a test burn/burn out. Definitely need a gasket around the cc door, smoke is leaking out around it. Still lots coming out of the chimney tho. We'll see how it is at temp when it's drawing well.

20130824_191408.jpg

• munxcub
• Aug 24, 2013

(Don't mind the GUR behind it...)

 

[munxcub]

Burned for about 3 hours in a chimney full of charcoal with some wood chunks. Got as high as 300 in the cook chamber. Very different than my WSM going to take some learning. Very reactive to changes to intake vents. Might need to add fuel every couple of hours, which is something I'll miss moving from the WSM (get 6-7 hours on the initial load)

 

[bullypitbbq]

Looking good!

 

[munxcub]

Not sure what I'm doing wrong or if I need to make adjustments. I seasoned it and have some ribs on for supper. Holding ~240 which is great, but my intakes are all wide open and it is crushing fuel. Granted it's a bit windy and my WSM would have no chance without a wind break... Will it be more efficient burning all sticks? Right now I'm charcoal and chunks.

 

[daveomak]

Have you got a non-contact Infra Red therm to check surface temps of the smoker and FB.....   Have you tried closing down the lower air lnlets to about 1/4 open and open the upper about 1/4 open..     Is the FB substantially hotter than the CC...      Did you seal up the air leaks yet.....    And I was looking at the picture of the open CC and was wondering  about the lower end of the exhaust stack....   Looks pretty low and I can't tell if it is cut at an angle...... 

Dave

 

[daveomak]

Having all the intakes to the FB wide open, there could be too much cold air entering the smoker, cooling it off....  Dave

 

[munxcub]

Dave,

If I close the intakes to a 1/4 open the temp drops big time. 

The FB is substantially hot. 

I have not sealed the air leaks yet, I need to find a proper gasket, might need to order one.

The stack is 1" above the top of my cook rack. It is not angled off.

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It was quite windy yesterday, which has me pleased that it could maintain temps at all. I think my first step is to get that CC door sealed up, then maybe look at cutting off the bottom of stack a bit?

Will the coal/fire basket I made have an effect? It is up high enough that my intakes feed air in below it. Also, the FB end is hotter and I will need to add a heat shield in there, which might help direct heat into the CC now that I think about it...

I'm guessing it took 300% more fuel than expected, and much more frequent reloading. 

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The ribs came out pretty good, no Q-view I'm afraid. I was called out to a big grass fire with a couple hours to go so my wife finished them up. I missed supper by a couple hours but even cold they were good. The house smelled great too.

 

[daveomak]

Dave,

If I close the intakes to a 1/4 open the temp drops big time. 

The FB is substantially hot. Indicating lack of air/heat circulation/movement...

I have not sealed the air leaks yet, I need to find a proper gasket, might need to order one.  If your smoker has air leaks, you cannot control the heat properly....

The stack is 1" above the top of my cook rack. It is not angled off.  The food racks are probably blocking the air/heat flow to the stack....  In a gravity/thermal type smoker, anything that impedes the air flow is bad....

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It was quite windy yesterday, which has me pleased that it could maintain temps at all. I think my first step is to get that CC door sealed up, then maybe look at cutting off the bottom of stack a bit?

Will the coal/fire basket I made have an effect? It is up high enough that my intakes feed air in below it. Also, the FB end is hotter and I will need to add a heat shield in there, which might help direct heat into the CC now that I think about it...  Having the air feed below the basket is good... then the lower air inlet controls the heat of the fire.....  Then the upper air inlet can move the heat from the FB to the CC without adding more heat....  If the FB is too hot, the upper air inlet should cool it off and move that extra heat to the CC.....  I'm not sure you understand the physics and philosophy of the two air inlets and how they operate...

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The ribs came out pretty good, no Q-view I'm afraid. I was called out to a big grass fire with a couple hours to go so my wife finished them up. I missed supper by a couple hours but even cold they were good. The house smelled great too.

Here is a drawing from another members build....    Cutting the stack at an angle improves the air flow out the stack....  Also eliminates the interference from blockage from the meat grate....  The 2 alternatives below, are very similar in efficiency for air/heat flow....  

First thing to do.......    Try cutting the stack as pictured at, at least a 45 Deg angle..60 Deg would be better (from horizontal)...  then I think, most of your issues will be lessened...  The smoker should draw better..  Door may not leak as bad, or at all...   the FB will cool down and the CC will warm up....  and you will be happy....    How about that for a diagnosis.....    Dave

Stack ideas.jpg

• daveomak
• Aug 26, 2013

 

[munxcub]

Dave,

Thanks I'll try cutting the stack off as you say. I do understand what the two intakes are for. Bottom for fire temp, top for cc temp more or less.

 

[daveomak]

Cool....   Sorry, no offense intended......    Seeing the smoke come out the door, is indicative of a stack not working....  at least I see it that way...    Dave

 

[munxcub]

No offense taken, I'm here to learn. I had seen somewhere saying the stack should be 1" above bottom rack, and if I cut it off at an angle I saw that as being not a lot different than raising the stack to the highest part of the angle. I can see it now as widening that level of the thermal layering inside the cook chamber, giving it a wider lane to flow heat to the stack.

Once it got up to temp there was no smoke around the door (or very little anyway). But I do suspect it's not drawing as well as it should. Smoke was coming out the top intake a little, which is not how that should work. 

I will cut the bottom of the stack at an angle and try to track down some wood stove gasket or something for the CC door. I'd also like to find a source of firewood that would be appropriate. Any hardwood should suffice eh? Might have to bite the bullet and get a pallet of apple firewood from Alberta... heh

 

[munxcub]

I think adding the heat shield inside the firebox might help the heat flow under the RF plate. If you look at the opening

20130707_212003.jpg

• munxcub
• Jul 7, 2013

There is a lip there coming down from the top. If I tack a heat shield even with the top of the half moon opening, that should alleviate the hot spot in the CC and help streamline the heat flow. 

And in case anyone was wondering... this thing is heavy. I can't imagine how heavy the 250-500 gallon jobs are. wow.

 

[munxcub]

Well here is some next day, warmed up for lunch, leftover ribs Q-view.

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• munxcub
• Aug 26, 2013

Don't mind the dirty plate, was my second helping.

 

[doodleq]

Late to the party, but I'd have to agree that you flow is somewhat compromised if you're getting smoke from your upper FB vent. I can "make" mine do that if I close my cc chimney before opening my warmer (effectively auxiliary) chimney. You must be close though, so Dave's suggestion seems like it would be worth a go. In the same circumstances above I can also "force" my cc doors at smoke a little, but it goes away entirely with adequate chimney flow. Sounds like you're close. Good luck!

 

[munxcub]

I feel that cutting the chimney off at an angle and getting some rope casket for the CC door should do it. I can even get some of the rope gasket locally which is nice.

 

[radioguy]

Munx,

You are there man!  Good job, just a bit more tweeking an it'll be a fine smoker. 

RG

 

[munxcub]

Well I hacked off the end of my chimney at an angle. Did my best with the grinder. The picture doesn't really show how angled it is, it doesn't look very angled in the pic.

20130831_145140.jpg

• munxcub
• Aug 31, 2013

 

[radio]

I didn't read through the whole thread to see dimensions of the stack, but in the pic it looks kinda small diameter for that size CC and FB.  could just be perspective though