Newbie self builder reverse flow, two cooks, two fails.

If you could post pics that'd be great!!! Read this thread since it's very similar to your situation.

http://www.bbq-brethren.com/forum/showthread.php?t=247475

Are you familiar with the term thin blue smoke?

I cast another vote for needing pictures- since they are worth a thousand words and all. There are some pretty smart fellas on this site- they will get you squared away in no time.

When was the wood cut.?

Here's a link to the welcome page showing the home built smoker.

http://www.bbq-brethren.com/forum/showthread.php?t=247564

I wonder if the exhaust is too tall, the smoke is cooling as it rises and it's not pulling a good draft? Other than that, I don't see anything really obvious.


My unprofessional opinion is the exhaust is too tall or your wood is too green (not dried out yet).

thin blue smoke?

smoke ninja said:

Are you familiar with the term thin blue smoke?

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I'd say he had at least a passing familiarity with the term.
He might not have had enough practice getting there but he did use all those words: thin, blue and smoke. :-D

I'd be sort of interested in the type of wood or if it had been seasoned or how long. He did mention having his exhaust come down to grate level- if he's getting stagnant nasty smoke...

Yup exhaust looks too tall. Cut a foot off, maybe even 16"-18"......

Nuco59 said:

I'd say he had at least a passing familiarity with the term.
He might not have had enough practice getting there but he did use all those words: thin, blue and smoke. :-D

I'd be sort of interested in the type of wood or if it had been seasoned or how long. He did mention having his exhaust come down to grate level- if he's getting stagnant nasty smoke...

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Sorry. Im under the weather and will admit to not completely reading the op

Don't feel sorry about being sick- get well and back to your old Ninja self. I never can remember "feed a cold or starve a cold- so I just eat" :-D

Unless it is losing a lot of heat, a taller exhaust creates a stronger draft, not a weaker one. If you want to be sure, you can wrap the chimney in a blanket to insulate it a bit and quickly see that it won't solve your problem.

I suspect the issue is with the fire, or possibly green wood, with airflow the third choice.

Assuming the wood is seasoned, your description screams not enough coal bed in the fire box. To start the fire, you can use a little charcoal, but then add several splits. Maybe 3-5 depending on size, not the one at a time you are describing. With exhaust and intake vents wide open, and maybe the cook chamber door also open at first, get a good fire going. The logs should be well engulfed in flames with little visible smoke. Shut the doors if open but leave the vents for now. If it is too hot, let it burn down for a bit. Once you have a good base, add one or two splits at a time to maintain temperature. If your splits take a while to light and give off a lot of smoke when you add them, they are too green or your coal base is too small.

Instead of wasting meat, try a fire with the smoker empty. If it is still giving off white smoke try heating logs in the cook chamber (while maintaining a fire) for a couple of hours before throwing them on. That should help "kiln dry" them and if not, you will see moisture coming out of the end grain if the wood is too green. Adjust until you can maintain a clean burning fire with thin blue smoke before adding meat.

The other potential issue is the outlet from the firebox to the main chamber. The air flowing through there is at its hottest and its density will be much lower than the intake air or the air leaving the chimney, so it needs the largest cross sectional area. If you rule out green wood and you still can't get the fire to burn cleanly, you have an airflow issue and we can look into smoker design issues to try to address it.

I often do pork butts on a stick burner for 10-12+ hours without wrapping them. They are never over smoked or bitter. If you have a good clean burning fire it should never be bitter and it should be very difficult to oversmoke pork or beef on a stick burner.

Hey Blondy_UK,

Smoker looks good but your exhaust stack is WAY too tall for such a small cooker. One thing you have to remember is that the exhaust stack will draw the hot air out of the smoking chamber, but if it's too tall the smoke will cool and no longer be buoyant so it will fall back down your exhaust stack and your smoke will become stagnant and bitter.

There are quite a few calculators out there which will take the dimensions of your smoking chamber, firebox, and exhaust stack and it will tell you what you need to alter. Your firebox looks good like it's a good size for your smoking chamber, but your stack is quite a large diameter pipe and I believe it's quite a bit too long.

http://www.feldoncentral.com/bbqcalculator2.html
Give that a try and see if it will help you out.

As for your firebox, make sure that you've got a fully oxygenated and energetic fire, and not a bunch of smoldering wood.

Good luck!

Where are you guys coming up with this nonsense about the chimney being too tall? Yes it is possible, but it would need to be much taller than I see in the pictures.

Stick a heat probe in the chimney at different points and let us know how much the air is really cooling per foot. It only takes a fraction of a degree difference in temperature for the chimney to draw air up, so unless he is trying to cold smoke in there, the flow rate should keep the exhaust temp at the top of the chimney over 100 degree F hotter than ambient. FWIW, with steady weather, the tiny heat output of an AMPS is enough to keep a draw going through my Lang 84 with the chamber temp 1 degree or less above the abient air temp.

BTW, Feldon is complete bunk.

m-fine said:

Where are you guys coming up with this nonsense about the chimney being too tall? Yes it is possible, but it would need to be much taller than I see in the pictures.

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Agree 100%

Hmmm. Im also in the camp of kinda thinking the stack is too tall. Not only is it tall, but it seems to be a fairy large diameter which would compound the problem. Not sure though, would hate to cut it off for no reason. When you have your fire established, do you feel good airflow? Weak? Does it come out in waves or burps? Im just taking stabs in the dark. Nice job on the build though. Im betting you can sort this out.

I'd cut it down just so it looks Normal....... :twitch:

How big is your end gap at end of reverse flow plate.?
.

I wonder how my wood burning stove could possibly work with an 18 foot tall chimney? Oh that's right, the specs call for a 15 foot minimum chimney rise. But what do the engineers, testing labs and building code people know anyway?

m-fine said:

Where are you guys coming up with this nonsense about the chimney being too tall? Yes it is possible, but it would need to be much taller than I see in the pictures.

Stick a heat probe in the chimney at different points and let us know how much the air is really cooling per foot. It only takes a fraction of a degree difference in temperature for the chimney to draw air up, so unless he is trying to cold smoke in there, the flow rate should keep the exhaust temp at the top of the chimney over 100 degree F hotter than ambient. FWIW, with steady weather, the tiny heat output of an AMPS is enough to keep a draw going through my Lang 84 with the chamber temp 1 degree or less above the abient air temp.

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This is a good post but you're also comparing a Lang versus a homemade project. We know the Lang is built to specific specifications and has good airflow, and those things are unknowns right now on OP's smoker. I will also point out that the smoke stack on OP's cooker appears to be of a similar diameter to your Lang, but is obviously MUCH longer. Just things to keep in mind and if OP is stating that they are having an airflow issue it's certainly something to look into.

You put forth a great course of action though to temp the airflow in the stack and see if it's actually pulling any air. OP is saying they are getting TBS, so if that is correct, and they are still having food come out so bitter it's inedible what do you think the problem might be other than airflow? The firebox looks adequately sized for that smoker and it appears to be in an appropriate place to allow for the heat and smoke to rise up and over into the smoking chamber. All in all the exhaust stack appears to be comically out of place on such a small cooker so I think reasonable deduction points there.

As for Feldon being bunk, if that's true, then good heads up. I just googled something so that OP had a place to start.

m-fine said:

I wonder how my wood burning stove could possibly work with an 18 foot tall chimney? Oh that's right, the specs call for a 15 foot minimum chimney rise. But what do the engineers, testing labs and building code people know anyway?

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Now you're just getting crazy by comparing a vertical burning stove against an offset reverse flow smoker. As for the engineering component OP stated they just made it as they went and had no idea about which kind of dimensions would be appropriate. It doesn't sound as though OP consulted any engineers or blueprints while making their smoker... kind of really shocked by the lack of thought in your post.

Here's what OP said in their Welcome Post about this smoker :
"I had not realised that there were rules and calculations that went into these machines"