Insulated Firebox vs. Cooktop/Griddle Firebox: Advantages & Disadvantages?

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phxbbq

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I’m going to purchase a offset smoker, 24”D x 60”L, w/ FB 24”x24”x22”. All steel mentioned from here on is ¼”, unless noted otherwise. I have the option to upgrade to an insulated FB. The standard FB has the ¼” griddle on top along with the lid. The insulated FB will be made of insulation sandwiched between plates leaving an inside dim of 20”x20”x20”. This will be used for home use and I plan to “maybe” small-scale cater/food truck with it in the future. Competitions may be considered in the future, as well.

I am leaning heavily towards upgrading to the insulated FB. I like it for its efficiency and its ability to control temp spikes. It will eventually pay for itself in fuel costs, though that will be a few years down the road.

I like the idea of perceived versatility with the cooktop/griddle top FB, but don’t know if I would get as much mileage from it compared to the insulated. Aside from cooking some bacon/eggs/steak on its top for breakfast, I don’t see much use for it. Heating a pot of beans, maybe? I would never use it to grill food over a grate in the firebox, so that doesn’t appeal to me.

Questions for those with griddle tops: what else have you used it for? Do you wish you had gotten the insulated, instead? Why?

Questions for those with insulated: does it control temperature spikes well? Is the fuel efficiency greater than 50% increase? Do you wish you had gotten the griddle top, instead? Why?

Thanks in advance for the feedback!
 
An insulated firebox will not control temp spikes, the effective mass is not that different. The primary benefits are safety and the paint lasts much longer. Improved efficiency is modest, so don't expect to save a ton of money on fuel costs unless you use it a ton and wood is expensive where you live.

The top of an uninsulated firebox is a crappy griddle in that you are controlling the fire for the smoker and accepting whatever temp the griddle happens to be. It works well enough to heat sauce, mops, or a pot of beans, and many people like to pre-heat their splits on top of the box to dry them out a bit and get a faster cleaner ignition.

Personally, I would want a firebox that is larger than 20x20x20. At the right price I would prefer insulated but I wouldn't pay a ton for the feature.
 
I see you are in phoenix not sure I would put dollars into a insulated box.
 
I've been eyeing Lone Star Grillz for a while and I've been dreaming of their 24x60 offset pipe smoker. I've also liked their warming oven choice. To me, that's much more versatile for what I would want to do.

Depending on what day you ask me, my 2 picks would be A) 1/2" thick upgraded firebox with warming oven on top, or B) insulated firebox.

I'm slightly tipping in direction of B) insulated firebox because with such a long cook chamber of 60 inches, I could see myself simply pulling out the tuning plates and doing a long slow low-temp cook on the far end near the smoke stack. A 60 inch cook chamber would also solve most capacity problems because, like you, I'm probably going to do smallish cooks in the future for friends/family.

Up here, a mile above sea level, conditions make BBQ slightly more challenging. I feel like if my next cooker didn't have an insulated firebox, I'd be kicking myself further down the line as to why I didn't simply pony up and get it done right the first time.
 
I have the warmer on my LSG and am happy I went with it. I can do just about anything I need to do with a stick burner. I got the ash pan for my FB and determined it is a PIA due to its weight, however in the warmer it makes a great deflector and I can cook in it like a griddle or flat bottom discada. I also use my warmer to preheat splits, can fit enough splits for a long cook and they ignite instantly. On the LSG the warmer upgrade and the insulated FB upgrade are the same cost. Again in Phoenix not sure I would spend dollars on a insulated FB.

Also I use the A-MAZE-N Pellet Smoker in the warmer on cool days and nights to smoke cheese.
 
Last edited:
BillN said:
I have the warmer on my LSG and am happy I went with it. I can do just about anything I need to do with a stick burner. I got the ash pan for my FB and determined it is a PIA due to its weight, however in the warmer it makes a great deflector and I can cook in it like a griddle or flat bottom discada. I also use my warmer to preheat splits, can fit enough splits for a long cook and they ignite instantly. On the LSG the warmer upgrade and the insulated FB upgrade are the same cost. Again in Phoenix not sure I would spend dollars on a insulated FB.

Also I use the A-MAZE-N Pellet Smoker in the warmer on cool days and nights to smoke cheese.
Click to expand...

Thanks for your ongoing input Sir! In my own head, it'd be either:

1) 1045 = 450 (1/2 inch upgraded FB) + 595 (warmer)
Vs
2) 595 (insulated FB), allowing me to buy extras like longer cook chamber and the stainless shelf

Thanks for chiming in on the ash pan which, despite weight, seems like a versatile piece. Who knows, I could switch again on a dime!
 
I have the LSG with insulated firebox and I am happy with my decision. I live in Texas so it doesn't get that cold here. Mine is a 24x48 so not huge, but the cook chamber seems to recover quicker after opening with the insulated firebox. As has already been mentioned it does keep the outside of the firebox looking nice.

As far as efficiency I think it is pretty efficient. Here is a pic of the fire it takes to maintain a 250 temp in the cook chamber:



and the temp with that size fire:



And just for grins one of my cooks on it;

 
sparctek said:
I have the LSG with insulated firebox and I am happy with my decision. I live in Texas so it doesn't get that cold here. Mine is a 24x48 so not huge, but the cook chamber seems to recover quicker after opening with the insulated firebox. As has already been mentioned it does keep the outside of the firebox looking nice.

As far as efficiency I think it is pretty efficient. Here is a pic of the fire it takes to maintain a 250 temp in the cook chamber:



and the temp with that size fire:



And just for grins one of my cooks on it;

Click to expand...

Nice data sparctek! Are those pieces of metal on the fire grate to allow for even more ventilation? Looks awesome. I must say that's a modest fire to maintain 250. What tipped you insulated over 1/2 inch firebox?
 
Thanks to all for your feedback. It's appreciated.

IFB = insulated fire box

m-fine: I thought I read somewhere that IFB helps with spikes, but maybe that was for 1/2"...which would make sense. As far as the 20"^3 dims, I assumed since it was insulated the IFB could give up a little room and still perform efficiently. It's smaller than what Feldon recommends in the spreadsheet, so that's something I need to think about.

BillN: I do live in Phoenix...currently. I've lived in 4 different states in the past 12 years, so I try to never say never. With that said, I would think you would still get even more efficiency with the IFB. If I knew for absolute certain that Phx was my final destination, I don't think I would insulate. I also considered going 1/2" FB or even standard FB and using the ash pan as additional mass.

Notorious Q.U.E. You've nailed it. That LSG smoker is exactly what I intend to purchase. It's prettier than some girlfriends I've had. Daily I bounce from IFB to 1/2" to "screw-it-make-do-with-the-standard" FB. I'd love to pocket some money, but don't want to be kicking myself for not upgrading now by being cheap. Problem is: you can't upgrade later.

Sparctek: great feedback. Thanks for the pics. Do you find that you are getting considerable more mileage out of your wood?

Question for anyone: how about going standard FB and then draping an insulating blanket over it as needed? This literally just popped into my head and I have done zero research on it so don't know if I just asked a dumb question.
 
You will recover faster with an insulated fire box. The inside of the box will be more evenly heated and all metal top and bottom will be warmer. Where I live I would never get one without an insulated fire box. But, it gets -25 below zero F here.... It is a safety factor also with kids. With that said...... Your in AZ......

The griddle I would not do. Just me. No control over temps and defeats the purpose of insulated fire box. A warmer with control from fire box and control from the cook chamber makes a lot of sense.... And I do mean a lot.... That you can control the heat and do a griddle in the warmer if you really wanted to....

Whatever you do get stainless grates. You'll be happy you did..

JMHO..... Good luck
 
WE do not have an insulated fire box on our offset. It does feature a "warming plate," which is completely welded around it's periphery. As has been stated above, there is no real control of the plate temperature itself, as the fire must be geared to the requirements of the cook chamber.

What we can do, is cook a pot of beans on it, or even fry breakfast fare in a skillet placed on top. Sometimes the plate/skillet combination gets too hot, but placing small aluminum balls between the skillet and the plate seems to do the trick for lowering the temperature. The fire box top is a great place to sauté onions.
 
The 20" cube fire box is plenty big as far as enough space to burn the wood, but I prefer bigger as it is a heck of a lot easier to work in a bigger firebox. Insulated or not, the actual size of the fire you need for smoking temps is relatively small.
 
phxbbq said:
Thanks to all for your feedback. It's appreciated.

IFB = insulated fire box

m-fine: I thought I read somewhere that IFB helps with spikes, but maybe that was for 1/2"...which would make sense. As far as the 20"^3 dims, I assumed since it was insulated the IFB could give up a little room and still perform efficiently. It's smaller than what Feldon recommends in the spreadsheet, so that's something I need to think about.

BillN: I do live in Phoenix...currently. I've lived in 4 different states in the past 12 years, so I try to never say never. With that said, I would think you would still get even more efficiency with the IFB. If I knew for absolute certain that Phx was my final destination, I don't think I would insulate. I also considered going 1/2" FB or even standard FB and using the ash pan as additional mass.

Notorious Q.U.E. You've nailed it. That LSG smoker is exactly what I intend to purchase. It's prettier than some girlfriends I've had. Daily I bounce from IFB to 1/2" to "screw-it-make-do-with-the-standard" FB. I'd love to pocket some money, but don't want to be kicking myself for not upgrading now by being cheap. Problem is: you can't upgrade later.

Sparctek: great feedback. Thanks for the pics. Do you find that you are getting considerable more mileage out of your wood?

Question for anyone: how about going standard FB and then draping an insulating blanket over it as needed? This literally just popped into my head and I have done zero research on it so don't know if I just asked a dumb question.
Click to expand...

I'm sure an insulated blanket would help as traeger has an entire line of them for their cookers. However, for me, if I'm spending a ton of coin, I'd like something that's nice to look at.

Separate but related, what are your thoughts on the LSG vertical slow smoker upgrade? It's a ton of capacity and versatile but I wonder how it dings efficient fuel consumption. I also wonder how much I'd truly use it since I've got so many years of working just the main cook chamber.
 
Notorious, the extra metal is just 2 pieces of angle iron. I use that to keep the coal base nice and compact. After talking to several people and cooking on both half inch and insulated fireboxes I chose the insulated. The half inch is nice but still radiates a lot of heat out. Maybe it is in my head but the insulated firebox, while it still gets hot on the outside, just seems to transfer more heat to the cook chamber.

Phxbbq -- to be honest I have not made comparisons of how much wood is being used insulated VS not insulated. However, I can tell you the size of that piece that is burning in the picture I posted. I basically take a regular split of wood, cut it in half then split each half lengthwise. So, I have 4 small pieces of wood out of 1 split. Once the pit is up to temp I use 1 of those small pieces about every 30 - 45 minutes. Every now and then on a long cook I may add 2 when the coal bed starts to shrink.

But, remember my pit is a 24x48 so it is not that big.
 
So if you go with an IFB they will cut down the size of the FB as opposed to keeping it the same and adding the insulation to the outside of that dimension? If that's the case a 20" cube box is small for that size cooker IMO...
 
4ever3 said:
So if you go with an IFB they will cut down the size of the FB as opposed to keeping it the same and adding the insulation to the outside of that dimension? If that's the case a 20" cube box is small for that size cooker IMO...
Click to expand...

Correct, I believe it's always external dimensions and LSG keeps them uniform. Thus, insulation probably swings inward, eating up some interior FB space.
 
To answer your question yes you could drape/wrap a insulation blanket over/around the FB. I have the 1/4" FB and I am at 5000' elevation and have cooked on days where the high temp has been in the mid to upper 30's and the only thing I noticed it was easier to keep my temps around 260 to 270. On hot days my cooker runs 275 to 300. Granted I have a small cooker and I truly feel a larger cooker would allow the cooker to run at a lower temp if so desired. I have done cooks where it started to rain and I thought I would have trouble maintaining temps with the rain sizzling off the CC and FB, no change in temp, now I'm sure a monsoon downpour would be a different story. During the summer months my warmer with all dampers closed runs 200 to 225 in winter 175 to 200. I can run lower temps with exhaust dampers open and much higher with bottom dampers open. So the warmer is very versatile. I guess I am trying to sway you toward the warmer. The term warmer is a bit misleading cause it is much more versatile than just keeping food warm or warming splits.
 
BillN said:
I guess I am trying to sway you toward the warmer. The term warmer is a bit misleading cause it is much more versatile than just keeping food warm or warming splits.
Click to expand...

You know, you may have swayed me to your way of thinking. I think I may actually get the warmer now ILO the IFB. Thanks for your insight.
 
sparctek said:
Notorious, the extra metal is just 2 pieces of angle iron. I use that to keep the coal base nice and compact. After talking to several people and cooking on both half inch and insulated fireboxes I chose the insulated. The half inch is nice but still radiates a lot of heat out. Maybe it is in my head but the insulated firebox, while it still gets hot on the outside, just seems to transfer more heat to the cook chamber.

Phxbbq -- to be honest I have not made comparisons of how much wood is being used insulated VS not insulated. However, I can tell you the size of that piece that is burning in the picture I posted. I basically take a regular split of wood, cut it in half then split each half lengthwise. So, I have 4 small pieces of wood out of 1 split. Once the pit is up to temp I use 1 of those small pieces about every 30 - 45 minutes. Every now and then on a long cook I may add 2 when the coal bed starts to shrink.

But, remember my pit is a 24x48 so it is not that big.
Click to expand...

Thanks sparctek!! This is exactly the kind of gouge I'm looking for. That's wild that a quarter split keeps it running. A 48 is of course 4/5 the size of the 60 so that's still pretty darn good. I think you've helped clinch the decision in my head--insulated all the way baby!!
 
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