New guy/ new project

[BuyLowSellHigh]

For heat and smoke transfer from the heat chamber to the smoke chamber you should be able to rely on the chimney or stack effect.  You should have an inlet into the heat/smoke chamber, an opening between the two chambers and an outlet at the top of the upper chamber.  The inlet and outlet can be about the same size in area, and you can easily damper both for adjustability.  The transfer opening between the two chambers should be at least as large as the inlet opening so that it is non-restrictive for flow from hot to cold.

For forced convection within the meat chamber, a capacity of 10X the volume of the closed chamber should be plenty - you're not looking for a hurricane, just a steady, gentle stirring of the air.  In it's simplest form, just a circulating fan inside, will probably require that the motor be outside.  A more complex but probably more efficient design would be augment what would be natural convection by taking hot air from the top of the chamber, running through an external duct, then injecting it back into the bottom of the chamber.  A "squirrel cage" fan similar to pikeman's RR-switch cabinet would work great, but again don't overdo the  flow capacity.  If I did the calc right you have ~ 5.8 cu ft of volume, so something on the order of 40-60 cfm should be plenty.

Just a thought ... one design for the heat & smoke transfer that you might want to consider would be something similar to that used in the larger smokehouse from SausageMaker -- this one.  It is similar but larger to yours in that it has separate heating and smoking chambers.  In horizontal wall between the two there is a central hole that in the meat chamber becomes a stack with a deflector shield over the opening.  I don't think you need to extend the cap as high as they show, but the stack and cap allows the floor of the meat chamber to function as a grease catch.

[KRAKMT]

I really appreciate everyone's suggestions.
I had planned to use two chambers so I could separate the smoke process from the heating process. From reading many of the threads it seemed like the most efficient. And I had plenty of room under the fridge. I will post some more photos to show the progress and maybe a dry run. I can always add a fan or two after we see what our temp spectrum is. I had thought of the recirc plumbing from the top to the heatbox and was debating outside or inside but have to see if it is needed or if I am just over engineering.
We have a stainless defuser to go over the chimneys that lead up between the two lower boxes and with two cookie sheets to catch the drippings nothing should go down. We will stick our chimneys up a little to create a lip.

[KRAKMT]

UMMM,
Suggestions? The new 2" Milwaukee bi-metal hole saw manage to get through the paint after 4 minutes. Anyone know if they make a step bit in 2". Tells ya how heavy the metal inside is.
K

[KRAKMT]

Here is the latest photo

[BuyLowSellHigh]

Looking really cool!

I'm wondering if a metal blade on a jigsaw (hacksaw type edge) might be better for cutting through the metal liner ?  Drill hole, insert blade, cut away ?

[NePaSmoKer]

Porcelain coated metal. It chews up hole saws. a plasma cutter works good

[Habanero Smoker]

I've never used one on porcelain, but a Multi Tool Saw a.k.a. Sonic Saw, may work. If you have a tool rental shop you may be able to rent one for the day. You are probably won't have to cut through more then a 1/4", and will have to cut through both sides.

Or be on the safe side and rent a plasma cutter. That will make quick work of it.

[KRAKMT]

After the fiance recovers I will get some pictures posted. The welding shop couldn't plasma cut the holes because of the porceline liner and the paper backed insulation so they were able to grind off where the holes went and hole sawed in the tubes- stainless 2 inch tubes welded in.
Working on calking- I have some high temp silicon is that recommended?

[Mr Walleye]

I've used high temp silicone in the smokers I'm built and had no problem with it. It holds up well.

Mike

[KRAKMT]

Thanks Mr. Walleye. We will season it tomorrow.

[KRAKMT]

That looks like a very cool project!  Look forward to seeing how this goes.

A few of questions:

1.  What temperatures do you expect to run in the meat section of the smoker?

2.  How do you plan to control that temperature ?

3.  How does the smoke get into the meat section form the SG chamber ?

Test run went well, smoke flows out of SG and up the first hole.  I tied to get a pic of the smoke but not good enough photographer. Cool to watch as it streams up even without the front smoke chamber door on. I did get some reflux back out the SG mounting bracket when I open the main meat door and lost draft. Is that OK? I saw a horror post here of a burnt SG. It only lasts until draft restarts. Suppose I could open the bottom door anytime I open the meat area door.
The hot plate got the temp to 180 after along time. I guess I am now going to tackle the heating and PID. Time to reread all the posts about PIDS. I will go shopping for a fin element or two.

I did have a little acidic smell during the run- not sure if it was an overburnt puck or if I am getting a carcinogen off something. Any experts on toxins?

[Mr Walleye]

KRAKMT

On my large smoker, when I open the door, then close it, I do get some smoke backing up and out the generator. This resolves itself moments later when the draft corrects itself. I've never had any problems with my generator. I think the amount of smoke that gets in the generator in this situation is very limited. What you what to watch is that your top vent is open enough to allow the draft to develop as soon as possible after the door is closed.

I would suspect the acidic smell you got was off the high temp silicone. I know from my experience the high temp silicone gives of an acidic smell until it's fully curred. On my smokers I have ran smoke through them for a few hours at around 200 degrees to cure them. It does go away once it's curred fully.

Mike

[KRAKMT]

Walleye you are the barrier of good news. ;D The smell seemed like silicon and I had hoped that was what it was but the girl folks smelled it and.... I was also a little worried about the smoke venting since the stack is only 2inch but it recovers in under a minute. Just didn't want to burn the SG up.
Next, suggestions on PID and watts? I looked at your wiring diagram and calculations for the large one you did- seems like two 600 watt fins should be enough? I would think at 5.8 cu ft 30 or 40 pounds of meat would be max?   
would prefer 120VAC.
 

[Mr Walleye]

My first heating setup was two - 1100 watt finned strip heaters. These were 110v but had to be ran with a seperate power supply for each one. Although a single PID can control 2 seperate SSRs. Finned strip heaters are designed to have an air flo going over them. Without the air flow they will burn out prematurely. If you intruduce a fan in your design you will have to be carefull to not preasurize the lower "smoke" cabinet as this will cause smoke to backup out the generator.

It's hard to say on the size of element. I tend to go larger then I think and let the PID do it's job. Although keeping it running on 110v will limit the size. If you have a 1000 watt hot plate I would plug it in and throw it inside and see how it responds to 1000 watts of heat. It might give you a starting point.

Are you planing on having the element in the lower chamber as well?

If you use finned strip heaters and install a blower, where will your intake for the blower draw it's air from?


Mike

[KRAKMT]

I stuck the hot plate directly inside the smoker and the plate got it to 225 rather quickly. At 225f I opened the door for 1 minute- the heat dropped to 199 but raised back to 225 after 3 minutes.
so looks like I either need more power or a fan if I plan to use the lower heat chamber. I guess I could just put a couple bradley elements under my shield?
K