Advice on fire management in a 16x16 firebox

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Advice on fire management in a 16x16 firebox

Postby thejsug » Mon Oct 21, 2019 4:41 am

Hi everyone

I spent some decent cash in the UK to buy a smaller (but higher quality) offset smoker that's 5mm in thick steel, without much leakage which is great!

The problem? It's only a 16x16 firebox and about a 28x16 cooking chamber. So not huge but not cooking for many people so that's fine. The makes of this model suggest running it with the firebox lid fully open, or half way shut (using a wood split between the firebox lid to keep it open). The reason for this is when it's shut, the extra heat from the small size just eats up the log in no time. They also use Beech wood to get the fire going rather than coals with about 4 to 6 smaller splints (stacked 2x2 or 3x3 crossing each other) set alight to form the first coal bed.

I did my first cook on it over the weekend. A 2.5kg (5.5lbs) boneless pork shoulder (UK style, so not Boston Butt). It was hard work, a LOT of maintenance but it came out absolutely amazing in the end after about 9 hours of cooking (I kept it too low a bit long early in the process thus the time). In fact, I couldn't have been happier with the taste. Replicated Salt Lick in texas (Used their dry rub) which is what I was going for (only used Oak logs). WOHOO!!!

But I need advice. I've had a few hiccups that I'm looking for some expertise on.

The fire management method was hard work with this small firebox. I was consistently and frequently (every 5 to 10 minutes) having to rotate logs, stoke the fire, get things re-lit by moving around and blowing through the side. I often did close the firebox as the temp dropped when there was a small fire just to keep it going for a bit longer. I'd try keeping another split inside the firebox (separate) to keep warm to instantly catch - that seemed to work well but space was tight.

My question comes down to a couple of elements..

Firstly, when starting the fire using beech, what size splits should I really be using? Using the smaller split seems to light up nice and fast and turn to coals quick but the coals are fairly small. Enough to get a few smaller/medium oak logs alight which means it's done it's job but that's about it.

Next, with the oak logs, I need to learn better how to manage this as I had to give it WAY too much attention it seems. How big should the splits be first and foremost. Right now, I'm taking half a log, splitting into either 2 medium/large splits, or 3/4 smaller splits which burn up much faster. The problem with the smaller splits is of course, they just burn up into coals quickly so you need to add more, more frequently, and the heat is generally much lower (especially with the lid open) which is a problem for above 225 cooking it seems (or even above 200...).

The problem I had with the medium to large split sizes is that they would catch quite easily when pre-heated and give off a nice high heat (with the lid half closed, get to 250 no problem or 225 with the lid fully open). However, after only a few minutes, the fire would disappear or go down to be a very small fire. I'd then need to rotate the log/turn it over. It would light up again for a bit, then go down. Then, I'd find myself adding a SECOND log to put them side by side with a gap in between, which would mean the new log sets alight and that fire keeps a fire burning on the other log too. Obviously the heat at this point goes up super high, which is fine when the lid is fully open anyway.

This process meant I was doing a LOT of opening the lid fully, closing half way, or even in some circumstances fully closing when the fire is getting smaller to keep the heat up. I was constantly attending to that fire every 5 to 10 mins for the full 9 hours to keep it cooking between 225 and 250. This seemed to be more attention than it should be - So what am I doing wrong? Should I always be adding 2 oak logs together and in theory should they just continue to burn till it's ready for more fuel? Or should I only be adding one log and with a coal bed good enough, the same thing?

LAST question (I promise). The grill thermometer built in to the lid goes half way into the main cooking chamber area. I bought a separate themometer to go on the grill plate itself but have found the temp difference is actually quite large. For example, the grill temp in the middle of the chamber at about 250f reads at around 300 (or slightly higher even) on the termometer at the top. Is this common and if so, is it common to be this big of a difference? Where is best to place the grill thermometer to get the most accurate reading for what the meat is cooking at (firebox side? chimney side? in front of the meat or behind it?). My worry here is that when I was cooking at 225, the space the meat was in was actually lower (thus the internal meat temp just not rising well). Once I picked up the heat to 250 on the grill thermometer it worked fine. I tended to ignore the thermometer on the lid but I guess I need to understand how the difference happens so I know what the meat is cooking at.

Appreciate all the advice here. Happy to provide pictures if required though the offset I'm using is below:
https://prosmokebbq.co.uk/products/blackfire-indiana-16

Thank you and appreciate your advice and all the content!

Josh
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Re: Advice on fire management in a 16x16 firebox

Postby GRailsback » Mon Oct 21, 2019 6:38 am

On my offset I run my fire box vents wide open, as well as the stack. Then control the fire and temp with adding wood as needed.
Last edited by GRailsback on Mon Oct 21, 2019 8:11 pm, edited 1 time in total.
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Re: Advice on fire management in a 16x16 firebox

Postby thejsug » Mon Oct 21, 2019 9:31 am

But with the wood, how much do you have to attend to it to keep it lit? That seems to be a key issue for me.
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Re: Advice on fire management in a 16x16 firebox

Postby k.a.m. » Mon Oct 21, 2019 11:12 am

It sounds like you are cooking with fire more than a coal base which can wear you out plus deliver some nasty smoke at times.
While fire management on a smaller cooker is hard it can be achieved. Can you post some pics of the cooker? I would like to see pics of the inside of the cooking chamber and the firebox plus the intake set up. Ideally you should have a coal base running and adding a wood chunk about 3" diameter and about 8" long about every 20 to 30 minutes.
Without seeing pics of the setup I am just guessing what I would do but in my mind I would start with about a half chimney of fully lit lump or charcoal and on chunk of oak. Once the chunk breaks down to embers you add another this is where the management happens. You need to find out where the cooker likes to run at in other words don t fight the temps. If it idles along at 250°/300° then you should be adding a chunk when the grate temp hits about 275°this will allow the temps to fall to 250° and climb back up to 300°. Once you find this rhythm you will have good fire management.
You should not be playing with the chunks to keep them burning every time you open the firebox you lose heat. You need to trust what is burning and recreating a coal base.
Trust your grate temps where your meat is cooking ignore the door temp for accuracy but use it as a reference to what is happening. Once you learn the cooker you will be able to look at the door and know what your grate temp is by the difference in the two areas.
Another thing Do not let a digital grate temp control your cook session it will fluctuate often just let it do its thing as long as you are humming along at your desired temp range. In other words if you drop or climb 10 or 15 degrees there is no need for intake adjustments as long as you realize your coal base is causing this.
Always remember slow and steady wins the race.



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Re: Advice on fire management in a 16x16 firebox

Postby GRailsback » Mon Oct 21, 2019 8:14 pm

What KAM has offered up here is very good advice. Your coal base is supposed to be sufficient to keep your fire going and replenish your coals. You shouldn’t have to be doing much of anything beside throwing wood in the firebox as needed. But you need to find out where the pit likes to run. Once you find that out you will have smooth sailing.
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Re: Advice on fire management in a 16x16 firebox

Postby thejsug » Tue Oct 22, 2019 3:13 am

k.a.m. wrote:It sounds like you are cooking with fire more than a coal base which can wear you out plus deliver some nasty smoke at times.
While fire management on a smaller cooker is hard it can be achieved. Can you post some pics of the cooker? I would like to see pics of the inside of the cooking chamber and the firebox plus the intake set up. Ideally you should have a coal base running and adding a wood chunk about 3" diameter and about 8" long about every 20 to 30 minutes.
Without seeing pics of the setup I am just guessing what I would do but in my mind I would start with about a half chimney of fully lit lump or charcoal and on chunk of oak. Once the chunk breaks down to embers you add another this is where the management happens. You need to find out where the cooker likes to run at in other words don t fight the temps. If it idles along at 250°/300° then you should be adding a chunk when the grate temp hits about 275°this will allow the temps to fall to 250° and climb back up to 300°. Once you find this rhythm you will have good fire management.
You should not be playing with the chunks to keep them burning every time you open the firebox you lose heat. You need to trust what is burning and recreating a coal base.
Trust your grate temps where your meat is cooking ignore the door temp for accuracy but use it as a reference to what is happening. Once you learn the cooker you will be able to look at the door and know what your grate temp is by the difference in the two areas.
Another thing Do not let a digital grate temp control your cook session it will fluctuate often just let it do its thing as long as you are humming along at your desired temp range. In other words if you drop or climb 10 or 15 degrees there is no need for intake adjustments as long as you realize your coal base is causing this.


Firstly, thank you SO much for your detailed reply. Here's some quick pics/videos of how things looked while I was cooking:
https://www.instagram.com/stories/highl ... 917423099/

If you don't have Instagram, I'll rip off some screenshots and post them direct.

As you'll be able to see, I was indeed cooking with a large fire and trying to keep that fire going at all times which is what the creator of this offset recommended (keep the lid open, keep the fire going strong). Saying it will wear me out is an understatement - 10 hours of doing something every 5 minutes (and going through an entire net of logs) was certainly more than I expected, but it's good to know it shouldn't be like this everytime, ha!

So it sounds like I need to:
1) Start with the lump coal bed and ignore his advice of starting with a load of beech wood splits to get the raging fire going
2) Use splits on the slightly smaller end. I.e the half logs in the bag I should be chopping into around 3 or 4 splits rather than about 2 thick ones
3) Keep the lid shut. I've always kept the chimney and vents fully open for as much oxygen/clean fire as possible but, mostly due to the smouldering when the fire dropped, it would end up with the thick white smoke (which is usually when I'd open the lid and stoke it/move the log/add more wood to get the fire back going again)

On the plus side, even with the crazy effort, it was worth it. Some of the pics in the link above don't quite show the juiciness but it was tender and delicious, and due to the constant attention it was nearly always a very clean smoke. I'd love to achieve results as good (if not better) with slightly less effort and fuel, ha!
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Re: Advice on fire management in a 16x16 firebox

Postby k.a.m. » Tue Oct 22, 2019 9:52 am

I do not have instagram but I would like to see some pics.
Always remember slow and steady wins the race.



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Re: Advice on fire management in a 16x16 firebox

Postby thejsug » Tue Oct 22, 2019 10:14 am

k.a.m. wrote:I do not have instagram but I would like to see some pics.


Here's some quick screenshots from Instagram:
https://gyazo.com/e2555a5feaca99ab7aad5d08a88f947c
https://gyazo.com/271f701fe2e7dda8c8e62e59f55baf66 (quite a large split on top of a burnt out smaller one)
https://gyazo.com/4977bce9d8247d50a02d95ec9fa118a8

I ran the thing with the fire lid half way open (propped up by a stick) and kept the raging fire going the whole time but will next time try the method with the lid closed and using lump charcoal for the base and smaller splits.
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Re: Advice on fire management in a 16x16 firebox

Postby k.a.m. » Tue Oct 22, 2019 10:25 am

Is the intake on the end door a butterfly?
Always remember slow and steady wins the race.



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Re: Advice on fire management in a 16x16 firebox

Postby thejsug » Tue Oct 22, 2019 10:29 am

k.a.m. wrote:Is the intake on the end door a butterfly?


Yes if my butterfly you mean like 2 vents that's controlled by one bit of a metal sticking out that's a disk that goes round to keep it closed or open. Yes. So that can be left open or closed partially/fully. I've been leaving that fully open (along with the chimney) while going with the continuous fire (with the lid half open too)
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Re: Advice on fire management in a 16x16 firebox

Postby k.a.m. » Tue Oct 22, 2019 11:43 am

Could you have a charcoal basket built to fit inside your firebox?
Something like 12" x 12" x 3"
If so this would help you control your coal base and keep it tighter and I would have the basket away from the cooking chamber opening closer to the end door.
Always remember slow and steady wins the race.



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Re: Advice on fire management in a 16x16 firebox

Postby thejsug » Tue Oct 22, 2019 11:50 am

k.a.m. wrote:Could you have a charcoal basket built to fit inside your firebox?
Something like 12" x 12" x 3"
If so this would help you control your coal base and keep it tighter and I would have the basket away from the cooking chamber opening closer to the end door.


I suppose so but I'll measure it to be sure. Would it be worth doing a dry/test run with a coal bed from a chimney full of lumpwood and a couple of logs on top to see how it runs first? Or do you think due to the size it will be too problematic?
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Re: Advice on fire management in a 16x16 firebox

Postby k.a.m. » Tue Oct 22, 2019 1:48 pm

thejsug wrote:
k.a.m. wrote:Could you have a charcoal basket built to fit inside your firebox?
Something like 12" x 12" x 3"
If so this would help you control your coal base and keep it tighter and I would have the basket away from the cooking chamber opening closer to the end door.


I suppose so but I'll measure it to be sure. Would it be worth doing a dry/test run with a coal bed from a chimney full of lumpwood and a couple of logs on top to see how it runs first? Or do you think due to the size it will be too problematic?

Oh I would definitely do the test run. Run with the top door closed and feed from the end keep your fire as far away from the chamber end as possible. Use your door intakes and run the exhaust wide open. You could feed from the top if need be but I would try the end.
Always remember slow and steady wins the race.



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Re: Advice on fire management in a 16x16 firebox

Postby thejsug » Wed Oct 23, 2019 2:30 am

k.a.m. wrote:
thejsug wrote:
k.a.m. wrote:Could you have a charcoal basket built to fit inside your firebox?
Something like 12" x 12" x 3"
If so this would help you control your coal base and keep it tighter and I would have the basket away from the cooking chamber opening closer to the end door.


I suppose so but I'll measure it to be sure. Would it be worth doing a dry/test run with a coal bed from a chimney full of lumpwood and a couple of logs on top to see how it runs first? Or do you think due to the size it will be too problematic?

Oh I would definitely do the test run. Run with the top door closed and feed from the end keep your fire as far away from the chamber end as possible. Use your door intakes and run the exhaust wide open. You could feed from the top if need be but I would try the end.


Perfect - thanks for the tips. I will source some more wood over the next couple of weeks and give all of this a go.

To recap:
1) About 2/3rd chimney of fully lit lump spread at the back side (away from the cooking chamber) of the firebox
2) Add on a couple of oak splits and let them burn for a while with the lid closed and all vents open to get the pit up to temp
3) Don't touch the fire - let it do it's thing even if the fire is small. Just let it burn... If temp starts dropping, add another split.. use smaller splits to keep things going. Maybe slightly bigger splits later in the cook when food wrapped etc

Will give all of this a go and see what type of temps I get with diff splits and with the vents open. Will also play around moving the grill thermometer to get a better idea of temp variation.

Much appreciated Sir!
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Re: Advice on fire management in a 16x16 firebox

Postby k.a.m. » Wed Oct 23, 2019 8:06 am

Try to use the same average splits throughout the cook. Larger splits are harder to ignite with a small coal base and will smolder.
Always remember slow and steady wins the race.



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