Double Wall Insulated Smoker (pit and firebox)

[EverydayDiesel]

Hello,

I am thinking about building a double walled (and insulated) for both the smoker pit and the firebox. Leaning towards 1/4" plate for each of the walls.

Is this a good idea? Will it help with temp regulation and maybe conserve on fuel?

FYI, I have access to buy 1/4" 4'x8' for really cheap.

What are your thoughts? What kind of insulation should I use between the walls?

Thanks in advance for any advice you can give.

[Cole Leffert]

What style smoker are you thinking about building?

[Dirtytires]

Insulating the cook chamber is not always a good idea. A smoker needs to loose certain amount of heat thru the walls as it does not all go up the chimney. Making it too efficient will mean you can’t have a fire any bigger than 3 toothpicks and a Lincoln log.

The firebox, on the other hand, is a great idea. It will burn a little less wood but will be much safer as the outer skin does not get a hot. No reason why you can’t use 0.25 plate for both walls but not sure I would. A thin outer skin is all that is needed as it only has to hold the insulation in. The thicker steel adds no benefit and really makes your pit heavy in a hurry.

Most here use either Rolux or a ceramic insulation. Just be sure it is rated to handle the heat.

[EverydayDiesel]

Insulating the cook chamber is not always a good idea. A smoker needs to loose certain amount of heat thru the walls as it does not all go up the chimney. Making it too efficient will mean you can’t have a fire any bigger than 3 toothpicks and a Lincoln log.

The firebox, on the other hand, is a great idea. It will burn a little less wood but will be much safer as the outer skin does not get a hot. No reason why you can’t use 0.25 plate for both walls but not sure I would. A thin outer skin is all that is needed as it only has to hold the insulation in. The thicker steel adds no benefit and really makes your pit heavy in a hurry.

Most here use either Rolux or a ceramic insulation. Just be sure it is rated to handle the heat.

Thank you for the response. I certainly have a lot to learn and I appreciate the input.

What style smoker are you thinking about building?

Ultimately I want an offset but lately I have been thinking about a hybrid approach where it can either make it offset or reverse flow. 2 stacks, one on each side and you would be able to use the 'tuning plates' or something very similar to direct the airflow.

Here is roughly what I am looking at

[dacolson]

Welcome!
I’m really glad you asked the question. I’ve been kicking around the idea of a small fully insulated patio smoker. I live in MN and we’ve already had our first 9” of snow. I already have a ceramic cooker - BGE - I can use all winter but I’d really rather use the offset running wood only - no charcoal. I know some folks use blankets to help with heat loss. Smoking below zero will suck down wood I imagine. I might try a smaller scaled down version - maybe 60 gallons - as a pilot model.

Anyone out there ever try this?
Dirtytires - have you run into someone running one?

[JKalchik]

I run my GF well below 0 F, and still only burns something like 1 1/2 lbs./hr of charcoal. Doesn't even radiate enough heat out of the bottom to melt snow underneath.

There's a thought..... use the GF basic cabinet design, but instead of the burn assembly/stack, hang an insulated firebox built for wood in it's place.

[tinspark]

I
There's a thought..... use the GF basic cabinet design, but instead of the burn assembly/stack, hang an insulated firebox built for wood in it's place.

I thought about something similar when I was designing my "Home Grown Gravity Feed". I had a crazy idea to open both ends of the walls at the transfer tube and have two furnaces on it (dual fuel). One end could be the traditional gf furnace with coal hopper. The other side would be able to burn wood. My gf can still easily be converted this way later if I choose to do that. I would just lose my collapsible shelf at the other side of my gf. Slide dampers at the transfer tube openings (handles to the back) may have been in order as well ...IMO

[JKalchik]

Hrrrrm..... I'd had the idea a while back for an aux firebox that inserted into the ash box on my GF for a cold smoke capability. Something similar could be done for a wood fired box, swing the ash door wide (or lift it off the bullet hinges,) slide the insert in, and off to the wood fired races.

[Dargo]

Hrrrrm..... I'd had the idea a while back for an aux firebox that inserted into the ash box on my GF for a cold smoke capability. Something similar could be done for a wood fired box, swing the ash door wide (or lift it off the bullet hinges,) slide the insert in, and off to the wood fired races.

Oh, interesting idea for sure. That could make it easily convertible. Should not be hard to even add this to mine.


Sent from my iPhone using Tapatalk

[dacolson]

I love this place. A bunch of brilliant crack pot fabricators hijacking this poor guy’s thread.

[Big T]

Frank is building a hybrid that can can go from offset to RF using tuning plates and twin stacks. I believe that there's a video on smokerbuildermfg facebook page. We lost a lot of pictures on the forum a few years ago after an update but there was a guy named bkndsdl and he built a fully insulated hybrid and he said it worked very well. I agree with the others that the 1/4'' for inner walls is perfect but I believe that it's overkill for the outer skins, not to mention that it would weigh a ton.

[EverydayDiesel]

I love this place. A bunch of brilliant crack pot fabricators hijacking this poor guy’s thread.

Oh i dont mind. I am just trying to figure out why there are so many GF in here. Maybe I need to rethink my offset build?

[Dirtytires]

One of the reasons people build a gravity feed is they like the convenience. Once it’s dialed in, you can just let it run. Add a controller and you get almost oven-like accuracy.

An offset is definitely more work and needs to be tended to every 45 minutes or so. Overnight cooks mean you don’t get much sleep but you are rewarded with an authentic, deep smoke taste which some have argued cannot be duplicated on a charcoal pit.

Really can’t go wrong either way but it depends on how much time you are willing to devote to each cook session.

[Big T]

[JKalchik]

Uh, yeah..... what @DirtyTires said.

I fought with a leaky horizontal offset for a couple of years... I am very happy with my not-quite-finished GF and stinkin' easy it is to turn darned good food. I burn a fraction of the charcoal, doesn't need constant babysitting (even with an ATC,) and I can smoke about 5x the food.

[EverydayDiesel]

Insulating the cook chamber is not always a good idea. A smoker needs to loose certain amount of heat thru the walls as it does not all go up the chimney. Making it too efficient will mean you can’t have a fire any bigger than 3 toothpicks and a Lincoln log.

The firebox, on the other hand, is a great idea. It will burn a little less wood but will be much safer as the outer skin does not get a hot. No reason why you can’t use 0.25 plate for both walls but not sure I would. A thin outer skin is all that is needed as it only has to hold the insulation in. The thicker steel adds no benefit and really makes your pit heavy in a hurry.

Most here use either Rolux or a ceramic insulation. Just be sure it is rated to handle the heat.

I think I follow what you are saying. If I hold more heat then it essentially means less smoke. Losing temp is actually a good thing.

What is the ideal thickness for the CC? 1/4"?

[Big T]

1/4'' is probably the most common thickness used on smokers.

[shearman23]

I think 1/4 loses heat over a very long period of time but it also absorbs the most amount of heat. 1/4 metal in your cook chamber absorbs heat and creates radiant heat that keeps overall temps more steady.

The thing here is 1/4" thick metal or insulated 16 ga. The only time your would you insulate 1/4" is in a firebox which is fantastic.
The Insulated 16 ga will absorb less heat in the cook chamber so it will take less time to warm up, making it more fuel efficient.
The insulated 16 ga will also keep temps steady due to the insulation and air gap.
The insulated 16 ga will burn out quicker and rust if exposed to high temps and not kept in good condition.
Both can be great and you could argue one is better than the other but it would be an opinion and not really based on any facts. (Like saying Beef ribs are better than Pork ribs, I'll take both)

Trager and others are insulating the bottom half of their pellet grills for efficiency now. Memphis and Grilla have done it for a while. Weber has a kettle that is insulated. Most are just air gap but it serves a purpose and increases fuel efficiency.

The question I guess, should be; Is the frame, 2 layers of metal sheets and insulation cheaper or more expensive than 1/4" plate? How much more time is fabricating a box with square tubing than getting 1/4 plate cut by a CNC and welding it up?

If you can get 1/4" cheap, I'd build a non-insulated cook chamber, either horizontal or vertical and offset a fire box either insulated, or not.