Looking for some Help: Offset Fie Management Problem

[kevin james]

As the title suggests, I’m looking for some suggestions to solve a fire management problem in my reverse flow offset.

I’ll give the background of what is going on, but long story short, my fire is too tall and I need to figure out how to build a “small, hot fire”.

Background:

I’m running a Kat 24x48 reverse flow and it has been great for everything I have cooked on it over the last year and some change since I got it, except for one thing…. Chicken. I have been having significant problems with the skin turning a very nasty looking grey color instead of that nice golden brown that everyone strives for. I have tried EVERYTHING to fix this issue over the last 6 months, and I FINALLY think I have found the cause. It had nothing to do with too much airflow as the builder and some others suggested. And it also is not a firebox or stack size issue, as both are in line with the recommendations per the Feldon’s calculator for my cook chamber size. Also, the fire has always appeared to run clean as the stack put’s out nothing but clear exhaust, no, white, black, grey or even thin blue smoke, just clean exhaust.

What seems to be causing it is the fire is too tall, and the flames are licking the top of the firebox and I’m guessing that is causing soot to be pulled in to the cook chamber which is then depositing on the chicken skin, causing the greyish skin color. I’m fairly sure this is the issue because I did a couple test cooks that seemed to fix that issue and gave me the nice golden brown skin color, but caused problems keeping a clean burn and keeping the temp up in the chamber.

The first test cook I pulled the firebox grate out which sits about 3 inches above the firebox floor, and I put my V shaped fire management basket directly on the firebox floor. Running it that way the flames did not touch the top of the firebox, and I got the golden-brown skin color.

The second cook, I took everything out of the firebox and built the fire directly on the floor of the firebox. Again, this kept the flames from touching the top of the firebox, and I got the beautiful golden-brown skin color I’m looking for.

The issue with both of these tests is that there was nowhere for the ash to go, so there was a ton of ash build up which I think caused problems with the coal bed and made it really difficult for splits to catch even after being preheated, and it was a struggle to keep temps up as a result.

So, it seems the REAL solution to the problem would be to find a way to build the fire in the fire management basket sitting on the firebox grate, and still keep the fire small enough that it isn’t licking the top of the firebox, and hot enough that it doesn’t have problems running between 275 – 300.

Currently I am running all white oak split’s, the wood is sufficiently seasoned, and splits are between 3-4” diameter and 16 inch in length. I have also sourced wood from couple different venders to rule out the wood source as part of the issue. My next test will be to cut the splits in half length wise using an alligator saw which need to buy, to see if that helps, although that will likely result in needing to add wood twice as often which would be one 8” long 3-4” diameter split every 15-20 minutes.

Any other suggestions would be greatly appreciated. I am determined to solve this problem one way or another!

 

[SmokinEdge]

You really should not be running flames to begin with. Build a bed of hot coals. Then add a split to that (for more coals) the heat should be coming from the red coals, not flame. Keep the flame to a minimum by introducing a single split to the coals at a time. Temp wise you may need to add a second split before the first is reduced to coals, but do that on the opposite side of the fire box. Your not running a wood stove to heat a house. Focus on maintaining a bed of hot coals, not a fire.

 

[zippy12]

kevin james - Did you buy this used? Did you clean out below the RV plate? put a light up in there from the fire box side....

 

[kevin james]

You really should not be running flames to begin with. Build a bed of hot coals. Then add a split to that (for more coals) the heat should be coming from the red coals, not flame. Keep the flame to a minimum by introducing a single split to the coals at a time. Temp wise you may need to add a second split before the first is reduced to coals, but do that on the opposite side of the fire box. Your not running a wood stove to heat a house. Focus on maintaining a bed of hot coals, not a fire.

Interesting. Although I'm not really sure how not to run flames. If the added split doesn't catch, then it would seem to just smolder which would cause dirty smoke. Do you just mean adding smaller splits one at a time to keep the flame as small as possible? That would make more sense to me and is what I'm going to test next, cutting my splits in half length wise to about 8", hoping that will keep the size of the flame down.

 

[kevin james]

kevin james - Did you buy this used? Did you clean out below the RV plate? put a light up in there from the fire box side....

No, I bought this new and I clean under the plate every few cooks.

 

[zippy12]

Interesting. Although I'm not really sure how not to run flames. If the added split doesn't catch, then it would seem to just smolder which would cause dirty smoke. Do you just mean adding smaller splits one at a time to keep the flame as small as possible? That would make more sense to me and is what I'm going to test next, cutting my splits in half length wise to about 8", hoping that will keep the size of the flame down.

do you put about 4 splits on top of the fire box for 1/2 hr before burning them? I have some dry maple but I have to dry it more on top of the fire box or some peices will smoke...

 

[SmokyMose]

I don't know your smoker, but when I add a split I leave the door open (mine's a top loader) until the split is actively burning, flaming like crazy,
then close the door and regulate with the intake vent. The flames will stop and the split will then smoulder away.
For what it's worth, I don't even try to get crispy skinned chicken in the offset.
Flames will send your pit temp soaring!

 

[kevin james]

do you put about 4 splits on top of the fire box for 1/2 hr before burning them? I have some dry maple but I have to dry it more on top of the fire box or some peices will smoke...

Yes, I do preheat splits on top of the firebox, and when I put a split in, I wait for it to catch before I close the door.

 

[kevin james]

I don't know your smoker, but when I add a split I leave the door open (mine's a top loader) until the split is actively burning, flaming like crazy,
then close the door and regulate with the intake vent. The flames will stop and the split will then smoulder away.
For what it's worth, I don't even try to get crispy skinned chicken in the offset.
Flames will send your pit temp soaring!

When you say you the split will "smolder away" when you close the door, that sounds like it would be producing dirty smoke and not a clean burn. I want to keep the size of the flame down, but I don't want dirty smoke due to smoldering .

 

[daveomak]

Feldon's leaves a lot to be desired...
Check out the tutorial the members on this forum, built smokers and verified the results that an awesome smoker is the result...

(1) Standard Reverse Flow Smoker Calculator... by DaveOmak and others... Ready to use.. rev5.. 6/19/15. | Smoking Meat Forums - The Best Barbecue Discussion Forum On Earth!

 

[civilsmoker]

What you are explaining is a fire air mixture issue.....you are trying to hit higher temps by increasing the flame.....with rather large splits. This larger flame will require much more oxygen than a fire box is designed for.....the result is a oxygen deprived fire and hence dirty un-combusted air mixture.....it takes a lot of air to burn a couple of logs like that.

This is the fire management I would recommend for high temp cooks......start with a full chimney of charcoal and get them very well lit to use as the coal base to promote combustion, next use smaller splits, ie 2-3 inches that are pre-heated (set them on top of the fire box). Add 1-2 splits well spaced such that air can flow around them let them burn but not uncontrollably.....it will take time to get the smoker up to 350-375 but it will get there. Next get the smoker up to that temp and let it run for 20-30 min to get in the zone then put air dry chicken in, it will come out golden....note you will probably need to add splits much sooner which is ok, just put a single two inch at a time so the air/flame balance doesn’t get messed up. For a hour cook you may have to feed it 5 or 6 times......no biggy.

So my rule is for long low temp cooks, coal bed and 3-4 inch slits, for short hot cooks coal bed (double that of a short cook) and smaller for frequent 2 to 3 inch splits....2 x3“ preferable.

this will hit 375-400 in my smoker.....

 

[sacedbysapp]

Didn’t u post this on bbq brethren?

 

[JWFokker]

Civilsmoker has the answer. Use coals to generate heat and small splits to put smoke on the meat. There is nothing wrong with using lump charcoal for your coal bed and less wood. It will burn very clean this way.

 

[Dantij]

I have the same exact problem! I cook on a Lang 48 reverse flow cooker and I have the same issues when I smoke chicken or turkey. I cook with a clean hot fire with little to no smoke exiting the exhaust. My splits are medium in size, and I preheat them every time. They ignite immediately, almost never creating the bad billowing smoke. I maintain a good sized coal bed and there's always a split burning in the firebox.
Kevin, I think we cook the same exact way. I can't just put a split into the firebox and let it smolder. That's producing too much smoke, and it is the undesirable kind of smoke we all try to avoid. My splits fully ignite when they hit the coal bed. Burning split replenishes coal bed. Repeat, repeat, repeat. My door remains open for @ 5 minutes. Sometimes I close the door, sometimes I don't. Am I doing this all wrong? I maintain temps between 240° and 260° all day long and turn out some pretty amazing ribs and brisket.

 

[kevin james]

What you are explaining is a fire air mixture issue.....you are trying to hit higher temps by increasing the flame.....with rather large splits. This larger flame will require much more oxygen than a fire box is designed for.....the result is a oxygen deprived fire and hence dirty un-combusted air mixture.....it takes a lot of air to burn a couple of logs like that.

This is the fire management I would recommend for high temp cooks......start with a full chimney of charcoal and get them very well lit to use as the coal base to promote combustion, next use smaller splits, ie 2-3 inches that are pre-heated (set them on top of the fire box). Add 1-2 splits well spaced such that air can flow around them let them burn but not uncontrollably.....it will take time to get the smoker up to 350-375 but it will get there. Next get the smoker up to that temp and let it run for 20-30 min to get in the zone then put air dry chicken in, it will come out golden....note you will probably need to add splits much sooner which is ok, just put a single two inch at a time so the air/flame balance doesn’t get messed up. For a hour cook you may have to feed it 5 or 6 times......no biggy.

So my rule is for long low temp cooks, coal bed and 3-4 inch slits, for short hot cooks coal bed (double that of a short cook) and smaller for frequent 2 to 3 inch splits....2 x3“ preferable.
View attachment 515135
this will hit 375-400 in my smoker.....

Great picture. That is about the hight of my flames, and at that hight they are licking the top of the firebox which I feel is at least part of the problem.

 

[kevin james]

Didn’t u post this on bbq brethren?

Yes, what's your point? I was looking for suggestions from as many people as possible, and there are people over there that are not here and vice versa.

 

[kevin james]

Made some progress this weekend, but still not satisfied. I tried the following:

1. Scrubbed under the reverse flow plate and the bottom of the chamber with a flat broom and used a blower to blow everything out the firebox end.
2. Cleaned inside the firebox to remove any buildup, and sprayed cooking oil to re-season.
3. Added Fire Bricks to the bottom of the firebox for better heat retention.
4. Cut my splits down length wise in half. They were between 6-8 inches long and between 3-4 inch diameter.
5. Started with a huge bed of lump charcoal (about 2 1/2 chimneys full) and lit with a torch, then closed the door and let it heat up for about a half an hour before adding any wood (Stack and door damper wide open, temp got to about 175 on the cook chamber).
6. Added 3 full size splits to get a good size fire going to get the cook chamber temp up and increase the coal bed size, shooting for 350. These were not the splits cut in half length wise, and I did this with the intent of getting the cook chamber temp to target. Stack was wide open, door damper was wide open. This only got the cooker to about 300.
7. Added some of the smaller splits, 1 every 15 minutes to get the temp up and started gradually closing down the door damper. The temp just never got above 325.
8. Put the chicken on after about an hour at 325, realizing the temp just wasn't going to get any higher.
9. I also stopped preheating the splits as I came to the conclusion that they were lighting just fine without it and it was keeping the flames smaller, where as they would rage a little to much if I preheated.

One mistake I think I made was the gradual closing down of the damper door. I think to get the temp up higher I just need to leave the door damper and the stack wide open as even with a huge coal bed this pit just does not like to go above 325, it just doesn't. Next time I may revert back to the standard length splits, adding one every 20 minutes or so asI'm not sure the shorter splits made any difference.

The skin color was better, but I still feel like there was some soot on it, although less than before, and it took 3 hours for a 6 LB chicken to cook. I'm wondering if the long cook time was because I injected with Tony Chechere's which I don't normally inject. I will eliminate that next time, no injection and try AGAIN to get the cooker up to 350. But that is a real challenge on this pit.

Here are a couple pictures. The first is just using the standard camera setting on my Samsung phone, the second is using the "food" setting. In person it looked a little more like the send one to me.

 

[Dantij]

Did you notice a difference with the fire bricks?

 

[kevin james]

Did you notice a difference with the fire bricks?

Maybe a little bit, but honestly I would need to play around with it more as it was only one cook and I also tried to get the temp up higher than usual. I usually cook around 275 but was trying (unsuccessfully) to get it up to 350 this time and pretty much topped out around 325.

 

[SmokinEdge]

Do you have any pics of your firebox?