Airflow problems in a modded Highland

[Odysseus]

I just got a OKJ Highland.

I've read probably 100 web pages about modding it to make it work better.
Here are the mods I did:
Made a 10x10x7" charcoal basket,
installed CC and FB door gaskets,
made a slide on chimney extension which seemed to draw the best at 27" vertical height,
LavaLock convection plate,
Made a 17x3x3" aluminum trough filled with 3 lbs. of sand and wrapped in foil, and placed it against the angled fire deflector end of the convection plate to act as a heat sink,
and added a Tel-Tru BQ300.

The good:
The smoker does not leak; no smoke escaping from CC or FB. The temperature is dead even across the CC (both therms were calibrated with boiling water). Yesderday's inaugural cook of short ribs turned out fantastic.

The bad:
Even with the charcoal basket full to the top of glowing coals, the smoker struggled to maintain 225 at the therms/200 at the grate. Chunks of well-seasoned cherry and oak just smoldered when placed on the coals -even with the FB ash cleanout door open. I had to position a box fan to blow air into the FB to get the wood to catch fire, then close the ash door (with the vent wide open) with the fan still blowing air into the vent to get the temp up to 250. As if that wasn't bad enough, it seems to burn a crazy amount of fuel while struggling to heat the CC. I had the smoker going for 8 1/2 hours and burned through TWO 16 lb. bags of Royal Oak All Natural briquets and enough cherry chunks to fill one of those bags to the top.

What can I do to make it hit and hold temperature without blowing a fan into the FB and without using so much fuel?

Please help!

 

[daveomak]

If this is the plate you installed, it is blocking the air flow from the FB to the CC...
What happens next is... your Royal Oak All Natural briquets are just burning up in the FB and not providing any heat to the CC....

My suggestion is to pull it out... Extend the chimney to 35" above the CC and give your smoker another test...
Deflector plates, Reverse flow plates should be placed at the top of the FB/CC opening to allow for full heat/air flow to the CC..

 

[Odysseus]

If this is the plate you installed, it is blocking the air flow from the FB to the CC...

My suggestion is to pull it out...

Tons of people swear by them, and it did even out the CC temperature perfectly -but that doesn't mean you're wrong.

What if I add a couple 1" holes to the firebox above the stock inlet (above the coals as per your diagrams). Would that help to move more air into the CC?

 

[gonavy]

I have an OK Joe Highlander, I find it almost impossible to get below 240 or so, I can get 275 pretty easily, 225 is hard. I have defuser plate just like the one you have, don't think that is the problem. What I don't have is that big exhaust tube or a basket. Use to have a charcoal basket. I quit using it when I gave up charcoal. I now use wood only, mini logs usually apple some time Hickory I use a weed burner to get them started about an hour before I put the meat on start with two logs maybe three if them are small, leave box FB doors open side and top, just before the hour (15 min or so) put another log on and close the top FB door and the CC door to begin to bring up to temps. Just before you get to desired temp start closing the side door and adjusting vent to hold temp, usually closed down to half way does it, every smoker is different. Logs burn much hotter, which is why I gave up on charcoal. I only have to add a log every 45 min or so 30 min if your using small logs to hold temps and smoke. Make sure you keep your next log on top of FB to heat them up, they will catch faster that way.

So my suggestion..lose the vent tube (go back to stock), and the basket, keep the plate and stop using charcoal (or if you do use them just to get your logs going) start using logs...it is called a stick burner for a reason, if you want a charcoal burner go buy a big green egg...lol

 

[pigbark]

do you have room to flip the first piece upside down?

 

[pigbark]

Tons of people swear by them, and it did even out the CC temperature perfectly -but that doesn't mean you're wrong.

What if I add a couple 1" holes to the firebox above the stock inlet (above the coals as per your diagrams). Would that help to move more air into the CC?

cant you just open the clean out a little bit? the Highlander is a Deluxe version of the Outlaw.. The sweet spot on them seems to be 260 to 280 F.. they want to cook.. there was times i had to open my cleanout about a inch when i used charcoal. i dont know why but it needed more air to operate correctly..

 

[Odysseus]

do you have room to flip the first piece upside down?

No. And that would cause all the fire and smoke to flow over the top of it which would have the same effect as just taking it out.

 

[daveomak]

What if I add a couple 1" holes to the firebox above the stock inlet (above the coals as per your diagrams). Would that help to move more air into the CC?

Well, they may swear by then but that doesn't mean they are getting all out of their smoker....
Yes, an upper air inlet above the fire, will help... It will move heat from the FB to the CC without adding air to the fire....

 

[Odysseus]

I'm also thinking that the 3" diameter chimney may be too restrictive now. The consensus seems to be: diameter= 1/5 CC diameter. Internal volume .22% of CC volume. For my 18" diameter x 35" long cook chamber, that would be 3.6" internal diameter chimney, right? If I went to a 4" chimney, it should pull air more effectively, right?

 

[daveomak]

Yes.... I didn't check that... but if your numbers are on, I'd go with a 4" stack...

 

[daveomak]

That POORLY designed elbow is another problem... It REALLY restricts air flow...

 

[Odysseus]

I can get a 3" chimney with a mandrel-bent elbow made for $35 and just put it in. To go 4", I'd have to pay someone to cut a 4" hole in the smoker, and weld the tube on, not to mention having to load the smoker and taking it to a shop (which I'd rather not do).

If I stick with the stock diameter (3"), do you think a mandrel bent elbow and the proper length would improve flow enough?

 

[gonavy]

OMG why are you going thru all this...stop trying to make this smoker do something it was never meant to do..listen you live in Arkansas I live in Jacksonville next to the Air Base...grab a couple racks of Baby backs and come to my house on the weekend...I'll show you every thing you need to know about the Highlander in the STOCK configuration...it is a wonderful smoker...all these mods you have done has screwed it up and now your not happy...smoking is an ART not a scientific endeavor, your never going to get this to keep a perfect 225 degrees with the perfect temps across the grates...it is never going to happen STOP trying and start working with what you have...LEARN your smoker...worry about what your cooking...I know this sounds harsh but dude your trying to hard..just smoke some damn meat...I have been turning out great Q for over six years with this smoker, the only thing I have added is a defuser plate (and it is just sitting there, not even bolted in) and a fire box angle iron grate that is the only mod that was needed..I can run 240 - 275 ALL DAY LONG putting a log or two every 45 mins...it just doesn't get any easier...I know you ignored my other post try to pay attention to this one..it will save you some money you don't need too spend...burn WOOD it is a stick burner I can't make it more clear then that...tough love...sorry but it has to be done

 

[daveomak]

Odysseus, now you have a choice to make... Get a few racks of ribs and take the gentleman up on his offer... There's lots to be learned there...

 

[Odysseus]

Gonavy, I think you're right about just using logs instead of charcoal. I'd love to bring a couple slabs of baby backs over and let you show me how it's done. Don't know when I'll have another free weekend any time soon, though. I started a new job and I've got three little ones at home. Hopefully soon, though.

 

[pigbark]

yep, grab a few racks and a few beers and head to gonavy's house..

im not sure if you ran the smoker without the mods first... i never add a mod until i see how the smoker runs first.. on these smaller offset smokers normally all they need is the heat rope on the CC and FB , possibly a basket or a thick wood grate..

if it was my smoker i would take the exhaust off,take the plate out, move the coal basket to the right past half way ,closer to the air intake.. then do a test run, if it is struggling to get the temp up , all you have to do is open the clean out a little to get more air flowing.. once you get to temp which is probably going to be 275 ish you can drop a plate in and see what happens to the temp, if good slide the exhaust back on, see what happens again.. do that with wood and charcoal.. the smoker will tell you what it likes... hope you get it figured out because those are nice smokers..