Alternatives to Cast Iron for "mailbox"

[jwed980]

Greetings All,

I like the idea of Mr T's cast iron oven "mailbox" for an external smoke generator.

I understand the key point is is its large thermal mass acting as a heat sink to condense and clean the smoke before being piped to the product chamber.

I've been experimenting with the AMAZN pellet tray/mailbox combination and see the downsides due to its lack of thermal mass. I prefer not to have to use excessively long ducting in order to clean the smoke effectively.

I've been contemplating construction of a relatively simple box that could be nearly as effective as the cast iron stove, and I'm asking for ideas as to what readily available materials I might consider using.

A few things I've thought of so far...
>Granite, quarry tile or other stone tiles
>Brick
>Concrete

I would welcome any and all thoughts/ideas on the subject.

Thanks for reading -

John

 

[daveomak]

A thin walled MB and corrugated aluminum flex duct works just fine... The thin walls dissipate heat and condense creosote perfectly... My flex duct is compressed to it's shortest length.. The corrugations, IMO, cause the air to swirl and "clean" the smoke....

Short flex duct... ....Creosote build up....


Smoked Turkey... No Creosote...

 

[tallbm]

Hi there and welcome!

Check out this post by johnmeyer:
http://smokingmeatforums.com/index.php?threads/mailbox-popcorn-mod-with-a-small-twist.258297/

He uses a tin popcorn container and some steel scrubby things as a filter. The popcorn tin is larger in volume and surface area to help dissipate heat to cool the smoke and the scrubbies work as a filter for creosote. He has some pretty convincing results that may give you some ideas on your build or hell you might just go his route.

Best of luck :)

 

[jwed980]

Thanks for the replies.

Last spring I did some experimenting with cheese cubes and the mailbox with AMZNPS. Cheese was allowed to reach room temperature before starting. Ambient temp was in the low-mid 60-deg(F) range IIRC.

My test setup also incorporated a draft inducer to pull the smoke from the top vent of the smoker cabinet, as with no heat source in the smoker - there was little draft to move the smoke through the cabinet. Without this, the smoke just more or less drifted in and out slightly due to the variable breezes present outdoors. Half the time smoke could be seen coming from the vents in the mailbox.

I began sampling the cubes after a short time and immediately noticed an "ashtray" sort of taste. Not exactly what I was expecting.

I suspect the relatively high ambient temp combined with pulling the smoke through the cabinet did not allow the creosote to condense effectively in the mailbox and corrugated aluminum duct before entering the smoker.

While I know I need to conduct the same test with a lower ambient and test my theory, I can't help thinking about ways to promote increased condensation before the smoke reaches the product.

Yes - had seen johnmeyer's mailbox-popcorn mod, along with Mr T's posts on smoke management. These are partially what had prompted me to consider other alternative methods.

-John

 

[daveomak]

When cold smoking, turn the smoker on for a bit to get it above ambient... then it will draw fine... I turn mine on and get it up to about 20 deg. above ambient... turn it off... add the pellet smoker and wait for the draft to take over.. add the "above ambient" cheese... the AMNPS keeps the draft going... smoker cools down to about 5 deg. above ambient...
If the smoker and all associated parts, including the meat, cheese etc. are NOT above ambient, the smoker will not draft..

 

[johnmeyer]

I was going to post earlier, not about my popcorn tin, but about whether cast iron is actually a good choice. I have not done any tests, so I cannot prove anything I'm about to say, but here goes.

One of cast iron's most important properties is heat retention: its mass can store a LOT of heat. This makes it great, when used in a skillet, for things like searing because even after you drop a big piece of meat on the skillet, it stays hot and scorches the meat. Thin metal pans don't do that.

At first blush, this would seem to argue for using a cast iron enclosure for an external smoking box because the cast iron will initially be room temperature and, as the smoking chips heat up, the smoke will hit that cool metal and the creosote will condense.

However, heat capacity is a two-edged sword. In this case, while the cast iron will stay cool initially, eventually it will heat up. Over the course of a 1-20 hour smoke, it will heat up to match the temperature of the chips and, because of its heat capacity, will no longer be very close to the outside air temperature.

By contrast, a really thin-walled box, like a mailbox or popcorn tin, will pass the heat right on through and, if the outside air is moving a bit, which it will even with a mild wind, that convection will keep the outside of the can relatively cool, and that coolness will pass right through to the inside surface and continue to condense smoke for the entire course of the smoke.

Whether any of this is true, I can't say, since I haven't tested, but at least for me, it keeps me from spending any time trying to get a cast iron enclosure, because I think the thin-walled metal enclosures work just fine.