PDA

View Full Version : Offset Smoker Insulation Help


ajones10
09-20-2017, 04:19 PM
Just purchased a gently used offset for a steal and I would like to insulate the firebox a little more and the barrels. I have looked into Kaowool, Firebrix, welding blankets, etc.

A few questions:

1. What product(s) would you use?

2. Where would you affix these products? Outside or inside firebox and/or barrel?

I have attached a few pictures. Any other advice or improvements that you can think of please let me know.

SmittyJonz
09-20-2017, 04:23 PM
An offset trailer smoker made with 18 gauge 55 gallon drums with a transfer tube from firebox :shock: :twitch:

Most use mineral wool or rockwool sheets between 2 layers of metal. Don't see how you can do that......maybe on the firebox.

LTG
09-20-2017, 08:06 PM
You need to sandwich the insulation between 2 pieces of metal as Smitty said. Assuming those are 16 gauge barrels, they are too thin imo. 16 ga=1/16th of an inch. What is the firebox constructed of?

Are you having airflow problems?

ajones10
09-20-2017, 10:18 PM
Thanks for the information. I am new to the offset world and like I said, I didn't give much for it so that makes me feel a little better.

Is there ANY way to remedy this situation? Make a bad smoker better?

SmittyJonz
09-20-2017, 10:22 PM
run it like a grill - charcoal n wood chunks fire in the cook chamber on firebox side - meat in center and other end.

Stlsportster
09-20-2017, 10:23 PM
Let's go back to the beginning. Why do you think it's a bad smoker and why do you think it needs insulation? Usually that's to help maintain heat in cold temp on a stickburner or for extreme fuel efficiency in a vertical charcoal smoker.

Since this is an offset stick burner what are you trying to fix with insulation?

viking72
09-21-2017, 05:37 AM
Cook with it for a couple of years, then make your changes.

Later,
Doug

ajones10
09-21-2017, 12:13 PM
Let's go back to the beginning. Why do you think it's a bad smoker and why do you think it needs insulation? Usually that's to help maintain heat in cold temp on a stickburner or for extreme fuel efficiency in a vertical charcoal smoker.

Since this is an offset stick burner what are you trying to fix with insulation?

That is a good question. Probably the root of some of my problem comes down to lack of knowledge of offset smokers. My thought was that since the metal was thin, it would not be as efficient a smoker. I figured I could add some modifications to make it more efficient.

My main goal is to smoke butts/ribs/brisket on a larger scale for my family and church than I currently do on my XL kamado.

So I guess my main question is, can that be done with this setup and is there anything I could do to it (modifications) that would make it better?

Stlsportster
09-21-2017, 01:29 PM
I don't see any reason you can't accomplish a big cook on that smoker without having to insulate...unless you live someplace with a harsh winter and plan to smoke in the snow.

Have you run a fire in it at all? Any idea of the temp swings from side to side and how it drafts?

Stlsportster
09-21-2017, 01:30 PM
Also can you get a picture of the connection between the firebox and the cook chamber? Need to see how big that is.

And maybe one of the inside of the firebox?

ajones10
09-21-2017, 02:09 PM
Also can you get a picture of the connection between the firebox and the cook chamber? Need to see how big that is.

And maybe one of the inside of the firebox?

I very much appreciate the help and advice. I fired it up for about 2 hours and it seemed by the thermometers (not sure if calibrated) that the right side (farthest from the firebox) was about 75 degrees less than the left side (closest to the firebox).

I will have the pictures up of the firebox and cook chamber within the next few hours.

I do live in Utah and winters usually range in the 20s-30s. I would like to cook during the winter if possible.

Thanks again

ajones10
09-21-2017, 03:33 PM
Also can you get a picture of the connection between the firebox and the cook chamber? Need to see how big that is.

And maybe one of the inside of the firebox?

Alright, here are a few pictures.

And they should all be rotated 90 degrees to the right. Don't know how to do that yet.

Cat797
09-21-2017, 03:52 PM
My gut tells me you are going to have trouble getting up to temp. I agree, no need to insulate at this point. You need to run it for a bit to get the basics down. Go grab some cheap oven thermometers (like 6 of them) and place left right center front to back. As you are running it note the temps. Thermos in the door don't tell you much about what's happening at the grate.

The reason I say you are going to struggle with temps is that both the FB to cook chamber opening and the stack opening look really small in the pics. Firebox looks to be a little small as well, but it's probably ok. Offsets are inefficient cookers, so you'll have to get used to that. Looks like you could enlarge the opening from FB to CC pretty easily. Maybe not so much the stack. Would really help to see the air intakes too....

What does the fire grate look like? You'll need to be able to build a fire and keep it running consistently by adding wood every 30-45 minutes or so. You want a clean burning fire emitting thin blue smoke.

Ed

SmittyJonz
09-21-2017, 03:53 PM
75* difference is pretty normal on a thin gauge smoker. Tunning plates or a convection plate can Help cut the difference down. It'd just be trial n error on that pit. I don't see any easy way to insulate it except covering it with welding blankets.

What size is the exhaust.? Offset smokers are all about Good airflow n Draft.......

Stlsportster
09-21-2017, 04:07 PM
Now we are getting somewhere!! Few more things.

Firegrate. Are you building the fire right on the bottom of that box or do you have a way to get the fire off the bottom and allow air under it?

Intakes. Is there a pinwheel or a slide or some other way to regulate airflow into the firebox. Once you get the fire going in most stickburners you shut the door and regulate heat by partially shutting down the intake. However in some cases you may need to leave the door open to get enough airflow if the design isn't right.

I agree the opening from the firebox to the smoke chamber may be too small. If the exhaust is the same size you may have airflow issues.

Part of what makes a stickburner have good clean smoke is airflow. We may have to work on that.

JS-TX
09-21-2017, 04:27 PM
What about firebrick on the inside of the firebox? At least on the top side?

ajones10
09-21-2017, 05:38 PM
Now we are getting somewhere!! Few more things.

Firegrate. Are you building the fire right on the bottom of that box or do you have a way to get the fire off the bottom and allow air under it?

Intakes. Is there a pinwheel or a slide or some other way to regulate airflow into the firebox. Once you get the fire going in most stickburners you shut the door and regulate heat by partially shutting down the intake. However in some cases you may need to leave the door open to get enough airflow if the design isn't right.

I agree the opening from the firebox to the smoke chamber may be too small. If the exhaust is the same size you may have airflow issues.

Part of what makes a stickburner have good clean smoke is airflow. We may have to work on that.

Firegrate I believe I have (see below).

There is not a pinwheel on the firebox. There are a few random half inch holes on the left side (I assume for airflow). The fire box is 20inx17inx17in.

The opening from the firebox is 6inx7in (picture below).

Part of the problem is I'm new to the offset world and don't know half the terms. Thanks for the time and walking me through it.

Cat797
09-21-2017, 06:15 PM
ajones10, you're doing just fine.....

Can you show us pics of the fire box door, and any other holes in the firebox?

SmittyJonz
09-21-2017, 06:28 PM
That is a fireplace grate for burning fire in your fireplace need to get you an expanded metal grate preferably two layers 90° crisscrossed to hold your call base up about three or 4 inches off the bottom

Somebody post a couple pictures of the firebox fire grates

SmittyJonz
09-21-2017, 06:34 PM
If you were local to me I'd come over and run a cook on that thing and check it out
maybe one of the Brethren are near you....?

Stlsportster
09-21-2017, 07:00 PM
Firegrate in my Lang. Off the ground a couple inches. Expanded metal to keep large coals up and let ash drop.

https://i.imgur.com/EGr3Y9dg.jpg

Adjustable pinwheels on firebox.

https://i.imgur.com/zD8gacbg.jpg

Stlsportster
09-21-2017, 07:02 PM
Also. Watch this.

https://youtu.be/BS1veMrDOC4

LTG
09-21-2017, 08:04 PM
I would start with an elevated fire basket made out of expanded metal. Even if you do not have access to a welder, you can assemble one and just bolt it together. Run it for a few hours, With the thin metal, do not be afraid to feed it 2 sticks at a time.

Stlsportster
09-21-2017, 08:36 PM
According to the Feldon calculator for that size firebox you should have 17.3 sq inches of inlet. So if those little holes don't equal that you need more intake.

Also according to the calculator the connection between your firebox and cook chamber should be about 46.2 sq inches. Yours is 6x7 which is 42... so it's a little undersized, but not significantly.

Eyeballing the exhaust looks ok...need the measurements of the cook chamber, the opening to the exhaust and the height of that stack to be sure...but for now I'd focus on the air intake and the fire grate.

SmittyJonz
09-21-2017, 10:39 PM
https://i.imgur.com/CZAoYrol.jpg

https://i.imgur.com/KiX5mBcl.jpg

https://i.imgur.com/XMW4GJyl.jpg

ajones10
09-22-2017, 04:11 PM
Again, thanks for all the help. I am in the process of making a firegrate. Here are some pictures of both sides of the firebox. Not sure if I need to make a pinwheel as well to allow for more airflow.

Guess I will just start running some smoke through there once I get the firegrate and see what happens.

Any other suggestions, please let me know.

SmittyJonz
09-22-2017, 04:26 PM
Or a slide intake......or cook with the door partially open.

Stlsportster
09-22-2017, 04:29 PM
Jones...it's hard to tell about those holes. Do they go all the way through to the outside of the firebox? From the other pictures I don't see them on the outside of the firebox.

When you run your test burn you may want to leave the firebox door cracked an inch or two and see if that gives you better airflow and a hotter fire.

Stlsportster
09-22-2017, 04:43 PM
I want to know what this part in the red box is?

https://i.imgur.com/RsPmDR8.jpg

Almost looks like those air intake holes are behind this part? Does that slide back and forth or move in some way to regulate air intake?

Assuming there is one on the other side too?

newtwoq
09-25-2017, 08:43 AM
You guys already beat me to Feldon's. I agree it looks like you for the most part are in the ball park for that cooker. I agree, a couple issues to focus on are a fire basket and I would run it with the door open a bit, let a good amount of air in. You will see +/- 25*F temp swings when you add a split and when you need to add one, you are aiming to average around a desired temp, you won't see it sit directly on any given temp and if you try to run her that way, you will drive yourself mad.

Click here to see the numbers we are playing with for you:
Link to BBQ Pit Calculator (http://feldoncentral.com/bbqcalculator.html?cc=0,0,82.5,0,0,0,19057.50,6352 .50&fb=20,17,17,0,0,5780.00,6352.50,91.0&ch=0,289.00,0&fi=0,0,0,17.34,0&fc=7.67,10.85,46.24)

SmittyJonz
09-27-2017, 08:36 PM
Well..... :twitch: