Help insulating firebox

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68pointbuck

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I recently bought a large smoker on a trailer... it's a home made job with some years on it. The smoker itself is in good condition, but the firebox on it isn't great. For some reason it is the lightest gauge steal on the pit, and it is showing some signs of rust and warping. It's not rusted through, and could be cleaned up and repainted and look fine for a while...

My question is, without cutting it off and building a new firebox (which I don't have the skills to do) what are some things I could do to help better insulated the box during the winter months. My last cook I sat some 12"x12" pavers on the sides and on top, just to help it retain more heat, but I don't know if that really did any good. Anyone else have this issue and have in tips?!
 
If you don't weld you could insualte and skin it with rivets. 1" sq tubing along edges and mineral wool/ rock wool sheets and rivet a skin on and use high temp sealant to waterproof under edges of skins. You can cut up to 1/8" plate with a circular saw and carbide blade.

https://www.mcmaster.com/mineral-wool-insulation

Thick. Wd. Lg.,
ft. R Value Flexibility Performance
Properties Each
Sheets
1" 24" 4 4.3 Semi-Rigid __ 9328K41 $7.41
1 1/2" 24" 4 6.5 Semi-Rigid __ 9328K42 11.11
2" 24" 4 8.7 Semi-Rigid __ 9328K43 14.81
 
Given your limited fabrication skills, the simplest solution would be to wrap it with welding blankets. The blankets will actually insulate the firebox and reduce heat loss to atmosphere. Ideally the best solution is to combine the exterior blankets with an interior firebrick type lining to reduce both ambient heat loss and temperature swings. Those concrete paver blocks you used may have reduced temperature swings, but in reality, they simply acted as heat sinks and once they were heat soaked, didn’t significantly reduce the actual heat lost to the atmosphere.
 
toymaster said:
Might consider throwing a blanket or 2 over the smoking chamber too
Click to expand...
I have a couple of moving blankets that I plan to use for that exact thing. Just to help keep the wind off of it. Hopefully it will help some! I have a bunch of cooks scheduled this winter, so it will be a learning curve for sure!
 
You could cut/have cut. 1/4" plate to the inside dimensions to cover the bottom. Just lay the bottom piece in there.
Have 2 inside side pieces cut. Just sheet metal screw thru/from the outside at the corners is all that should be required.
Then a new outside top piece cut. Again attach with sheet metal screws from the underside.
I'm guessing that should last a good long time. And easy to replace if ever required.
Leave both ends alone. Unless repair is required.
Much easier than removing/replacing/rebuilding. With pretty much the same results.
Just a thought.
 
ebijack is on the right track. Your firebox is similar to that of the old Bandera (which this website originated from). There have been various approaches tried over the years. I went with an internal lining of stainless steel sheet tht I picked up at a scrap yard and then cut & bent into shape. Worked great for years and then sold it.

I searched for pics and threads to no avail. Sorry but couldn't locate.
 
Yikes! You haven’t provided any hard numbers we can crunch, but based on the pics it appears the fire box volume is on the smaller side. That kind of rules out lining interior with fire brick. The door/vent design is going to make fabricating an exterior insulation with skin (that is effective) difficult at best. If it were mine, I would be using welding blanket on the exterior for the following reasons. First, blankets are inexpensive and easy to use. Second, a blanket can cover the entire box (except for vents) and be easily moved when adding fuel. Third, it will have no joints/welds/rivets to fail or loose heat. And finally, it can be removed when the smoker is not in use. Thus it will not trap moisture if it happens to be left out in the rain. Good luck.
 
Home Depot as a fairly cheap 6'x8' foot welding blanket. I will try that to start and see if it can get me through the winter. I'm not TOO worried about it, as I have cooked on some cool nights and the smoker has done pretty well... but with some larger planned cooked scheduled over the winter, I want to have something planned if I have to cook on a super cold night. Thanks for the feed back!!

I have a follow up question, but it might need its own thread.
 
68pointbuck said:
with some larger planned cooked scheduled over the winter, I want to have something planned if I have to cook on a super cold night. Thanks for the feed back!!

I have a follow up question, but it might need its own thread.
Click to expand...
Make a wind block. 4X8 (length/height your choice)sheet plywood cut in half length wise or width wise. Use a couple cheap hinges to hold together. Stands up or folds in half for easy storage.
A wind block will do more than the welding blankets in my experience. But you could use blankets and the wind block.
Just a thought.
 
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