Earl

[Rodcrafter]

Gizmo,
I think, (I know that could be trouble) when you build a smaller fire you will be able to control it better with the damper on the throat. It seems like the whole firebox became the fire rather than giving you control over the air moving through it. Since you began this discussion about the adjustable damper, I have been doing more experiments using mine. I found good results, I moved to using it wide open early on without giving it enough tries to prove it did work, then just learned how to work it with the larger opening. Maybe the thickness of the steel is making a difference too.
That is one very nice looking cooker by the way.

jm2cw

[Gizmo]

Thanks RC! …. the undercarriage and paint job should really help too.

Yeah I'm not too worried overall - I've got time for 2 more burns this weekend so I'll try lighting him with less fuel from the start then play with the opening. I've got right at $10 in materials and a couple evenings time in this idea so any knowledge from it is a great return on the investment. Even without the adjustable throat it's a solid cooker.

[Rodcrafter]

[Rev.Mike]

[Rodcrafter]

I've been thinking again, (I know) but I was wondering since we use the the three to one number to get the sizes of things like the FB to CC ratio. Do you BTU guys know if the temps work that way too? Do we need the temp to be three times hotter in the FB to get our CC temp to the point we want it at? So a person could be measuring the air temp coming from the FB to help determine where some problems are if that were true right?

I'll go back and sit down now.

[Gizmo]

Hmmmmmm

[Smokeone]

Gizmo, you better get Rick for this one!
But I definitely am intrigued on this one.

[Pete Mazz]

Oh boy, you got him thinking again! That can only mean another build.... and round of tests! Or is that smoke coming from Rick???

[Gizmo]

I think you're onto something there RC. I also think testing would have to be done on several different cookers and all those numbers plotted on a graph so a person could see where the most likely "operating envelope" is for FB temp vs. CC temp on several different cookers.

I think the conventional design of 3/16 or 1/4 inch steel walls prolly runs around 800 to 900F at the FB and a CC at around 225. We actually rely on the cooker "sweating" heat. Heat loss to the system is a HUGE consideration.

On the one hand - if we build a system that is too well sealed/insulated then we wouldn't be able to build a small enough fire to keep our CC down where we want it.

On the other hand - if we have a very thin-walled design with lots of leaks then we'll stoke the fire hard enough to burn the finish off the FB door (been there) just trying to get the CC up to a cooking temp we can work with.

The benefit of being somewhere in the middle is that letting a fire run at it's more natural hotter level is the generation of "thin blue" smoke - the GOOD TASTING stuff. A cold fire generates more carcinogens and tar and creosote - an acrid flavor …. too hot of a fire generates very little smoke so nowhere near as much smoke presence in the flavor of the stuff we cook (pellet drives).

I think (hunch) conductive heat transfer is very real but also very slow so I don't worry about it much - I just wait for it to kick in later then deal with it. Since my son is a mechanical engineer I put this question to him; "In a sealed system like our cookers, "how much of the heat transfer responsibility is due to radiant heat vs. convective heat?".

After some noodling on it he worked up a balanced formula between the FB & CC and came up with "they're about even" .
I've been mumbling ever since over that one ….

This is why I pay close attention to the "window" between the fire basket/throat/BP because the radiant heat is so significant.

Edgar had a FB temp gauge. It read around 600 to 650F starting out when the CC was at 250 - UNTIL he got hot and stabilized - about 2.5 hours into the cook. Then he read around 475F at the FB for the same cook temp - probably the re-radiant (conductive transfer) heat from the BP etc… Not exactly 3 to 1 but then again Edgar was an insulated design and I suspect it's not a true linear relationship either.

When I cut 2 - 2" X 6" inch openings in Edgar's FB roof to allow direct radiant heat to hit the underside of the BP it moved Edgar's happy temp from 230 to 260 immediately. I'm tending to believe my son's assertion.

…. but I'm rambling …. what the HELL were we talking about….?

…..move over RC - I'll join you in the corner ….

[Smokeone]

What he said....................... wait what did he say?
I think I need more coffee!

[Rev.Mike]

i have a question, what would happen on an offset reverseflow, if the firebox was moved more inward under the baffel plate so that more of the "lost" heat was transferred to the baffel, not saying all the way under, but maybe 1/2 or 3/4 of the way? or am i or should it not be tried?

[Puff]

Whew! And thought it was just an adjustable throat plate ?

[Rodcrafter]

Gizmo, thanks for the input and your son's help too. It blows my mind to think they are the same. I can see I'm going to be doing a lot of tests in the future.

Rev., I think it would work fine just have to know in advance you would have a hotter end on that end which isn't a bad thing if you have enough room.

But having heard the engineer's opinion and the input from the professor and others then "thinking" more about this it looks to me like if I put a FB inside another box creating an air gap around it to use as an air duct. I could then use a small fan to send the "lost heat" on down stream to the CC. The end result should be a much smaller fire needed. It seems to me.

I'm going to have to look into this one.

[Rev.Mike]

like a small heat exchanger around the fie box in a way then? hmmmm

[Rodcrafter]

Sorry!

It seems like we could capture what would have been lost to me.

[TuscaloosaQ]

Earl is a bad unit Rick!!!!!!! Just saw this post!!!!! Bad is good Rick at least in Alabama!!!!!

[Gizmo]

Thanks TQ!

[jaybird302]

But having heard the engineer's opinion and the input from the professor and others then "thinking" more about this it looks to me like if I put a FB inside another box creating an air gap around it to use as an air duct. I could then use a small fan to send the "lost heat" on down stream to the CC. The end result should be a much smaller fire needed. It seems to me.

I'm going to have to look into this one.

I'm relatively new to all this and have been sitting in the corner creeping on all you guys for a while now, but I did have a thought that I felt I could share and I think it's a good one, so here goes...

If we're talking about air gaps and radiant heating, it seems to me that building a warming cabinet around your fb would be a useful way to corral that lost heat. My parents house has one of those convection style fire place insert that blows the "lost" heat into the living room. Very effective.

Ok, I'll head back to my corner now... don't mind me.

[Gizmo]

Jaybird you're absolutely correct.

…. and in my experience, keeping the temp DOWN at a level that could be considered just a WARMING cabinet (140F) was the real challenge because it works SO well ….

If you look at the Edgar thread you'll see vents I had to add on the lower left hand warming cabinet - both front and back and it only shared one double-insulated wall with the FB …. jm2cw

[Puff]

EDIT: Gizmo, this is not the post I was replying to...but I can't seem to find it now so I will leave this here


I am very interested in your throat plate result. No my FB is still getting its' parts. TQ answered all my trailer questions and I've been jumping around doing things on several places of the project. My greatest planning involves getting everything LIFTED onto the trailer and getting it balanced correctly. It is finding methods of getting the heavy stuff in place. I do everything solo. I live deep in the woods. No neighbors and I hesitate to impose on friends since most are not just around the corner.

Is there a way to document the theory that there is no effect with the adjustable throat plate? I was starring into the tank this afternoon wondering how I am going to make a system to hold the plate at different levels of OPEN. You may have just negated all thoughts on following this mod. Especially that I have the 1/4" thick half moon cutout from the FB that will fit nicely into the tank throat. I'm sure you tried using the stack damper in combinations with the throat as well?

[Gizmo]

Puff my next smoker project is coming fast so I've put off more test burns on Earl to get him painted and moved outside to free up space in the shop. Maybe you can fashion something cheap for your cooker that could even be cut out later if you scrap the idea.

I wish I could tell you more but I can assure you that the way I am going is not going to yield big results. I still have to play with this idea and now that I've built Earl I hope in the coming weeks to learn a lot.

Got him up on his wheels….

[Big T]

A little paint and you'll be ready for the next build.

[Puff]

This photo has brought several things into greater clarity. Particularly when you said you'd lifted Earl onto the trailer. It appeared to me, even with the perspective of the pictures, that this was much larger than it looks. The " aerial " view of the rusty compressor in the first post made me think it was bigger. I think that I've seen so many 250 gallon tanks, pictures, builds, discussions, plans, etc, etc.my inexperience led me to believe that they are all gigantic smokers. I'd wondered where these 6" dial thermometers come from....

When I said I needed one for my son, one for my house and one for a friend all about the size of Earl, it is even a greater idea now.

When you think about any of the fireplaces, wood stoves and furnaces aren't they all essentially controlled at the firebox? So in trying to control temperature thru the cook chamber, where else is there an opportunity to make a change? I wonder if there is a benefit to reroute any exhaust gasses and super heat them again, then channel it thru the second baffle plate before sending them out thru the exhaust stack?

[Clover Ridge Smokers]

Dang Gizmo. That thing looks like crap

Just kidding buddy. Looks awesome like all you builds do.

[Puff]

Just went back to look at the "aerial" photo.... Ha, never saw the shopping cart or the lift handle on the compressor ! Dumb...