offset strange uneven temps

[rbbennett]

So got my refurb done so fired up on Sat to see how she runs and cooked Baby Back on her Sunday. She ran pretty good and ribs came out awesome. However, I was really surprised by the temps. Tried intake wide open, closed except for pinwheel open completely, smoke stack wide open and 1/2 closed, didn't seem to make much of a difference. Had great draw even when adding wood, I could see flames being pulled into the CC. What really threw me was that the upright (Probe 4 hanging between the two grates in upright) was higher temp by 40-60 DegF than the middle(probe 2) and far end (Probe 3) of the CC grate. Probe 1 was significantly higher (to be expected).

There is no real deflector plate, just a 3"X 1/4" strap across at grate level. also the far end is completely open to the upright.

Thinking its drawing too hard, but closing intake or exhaust should have helped that.

 

[rbbennett]

more temps

More temps

 

[Newglide]

It looks like you have 2 big logs flaming away from what I can tell.
I would think you have too much fire and your splits are a little big.
I have an Old country Pecos and it likes to run on smaller splits.
I use the same length but probably half the thickness. About the size of a 16oz can is what I burn. I also usually only have to put one split in at a time.
I haven't run a smoker with that also has a cook chamber on the stack so I could be way off base

 

[rbbennett]

The flames go down to 2-4" once lid is closed. But will definitely try smaller splits and try one down to coals, one burning good and new one. So only adding one at a time.

Also thought about adding plate blocking top third of area at end of grate to force the smoke and heat back down some. So it would basically act like a Franklin style collector with an upright chamber making up most of the smoke stack? Anybody got thoughts on that?

 

[Back9Q]

Can you draw sketch of smoker and where each probe is. Also what does photos of opening between CC and vertical look like?


Sent from my iPhone using Tapatalk

 

[rbbennett]

The arrow on the dwg is the flat bar that is horizontal even with grate. It's probably 2-2 1/2". The entire pit is made from 1/4" steel. FB is 16" OD the CC and Upright are 20" OD.

 

[txsmkmstr]

Couple of thoughts.....

Try swapping your probes around and see if the temp differences stay in the same place. I'm not surprised at #1 but maybe #3 is a bad probe.

Your fire appears to be rather large - not sure what stage of the cook the picture shows but I wouldn't think you'd need that size fire once the pit gets up to cooking temp.

Your firebox lid and intake if not sealed really well could allow just enough air (especially with that large "stack") to keep the fire hotter than you want.

Final thought - - - just cook with it and don't worry about exact temps. Find the sweet spot for temp, damper and fire size and ditch the probes.

Good luck and have fun.

 

[rbbennett]

Put all 4 probes in boiling water, making sure not touching pot. All four read 209-210. So not the probes.

Just don’t understand that big a difference in less than a foot and the upright being higher. Every lit I’ve cooked on with and upright, it was about 50-100 degs lower than the CC.

Just want to be able to use as much of the pit as possible.

Was adding two splits every hour and same prove temps didn’t fluctuate but about 20degs on whole cook.

The pic of the fire was just after adding splits and letting them ignite for about 3-5 mins just before closing lid.

 

[rbbennett]

Short of cutting a plate and welding it in, what can I do to play with baffles at intersection of CC and upright? Was thinking of cutting out cardboard or cheap 1/4" plywood and covering with several layers of tin foil to see what works and doesn't work first. would cardboard catch fire if insulated with foil at 200-300 degs?

 

[SmokeOCD]

Have you got the large aluminum pans (larger than the loaf pans in the pic)?
That would bend up nice, and hold it's shape pretty well without catching fire.
Maybe an aluminum wrapped brick to hold it in place.

 

[rbbennett]

Made this with wire coat hanger card board and wrapped with 6-7 layers of HD aluminum foil. Temps between middle and right side stayed around 10-20 dwgs. Still a hot spot at inlet from FB. Will try to make another one for there. Temps will be a lot hotter so may need to do something else but we’ll see. upright about 60-80degs cooler, which is more what I expected.

 

[Fooball]

Still a hot spot at inlet from FB.

You're always going to have that. Comes in handy sometimes when cooking different cuts or types of meat at the same time.

I would just make a couple different baffle sizes out of some more durable material to insert like you have in the pic so you can have different temps for different cooks if needed. Beats trying to rig up a full blown adjustable plate baffle which would be a lot of work if you don't have the torch/welder/steel to work with.

 

[CaptainQ]

I'm no expert, but you might try smaller splits, moving the fire closer to the firebox door, and decreasing the size of the fire as well as reducing the draft. Moving the fire closer to the door will prevent flames from entering or getting near the cook chamber. A smaller fire with a larger coal bed will produce more consistent and predictable heat.

Looking at the picture, the flames are angled 45 degrees toward the cook chamber. A good, slow fire will have short-ish flames that go almost straight up. Anytime the flames start to be pulled toward the cook chamber, I slow down the fire by opening the firebox door wider (I always keep the door vents closed). It seems counterintuitive, but opening the door wider will decrease the temperature. The wider you open the door the more the airspeed across the fire decreases. Once I get a good coal bed established, I can cruise around 275 with the door cracked 1 inch. When the fire starts to get away from me, I open the door as much as a foot and then gradually close it back down as the fire slows. I also use the stack damper in conjunction with the firebox door to regulate the fire. Closing the damper by 25% reduces the draft/airflow across the fire.

All that said, at least every other cook I seem lose complete control of the fire (as in 350 and rising). When that happens, I open the firebox door all the way, open the cowboy grill lid on the firebox, and open the cook chamber door to get the fire to slow back down... then laugh at myself for being an idiot. Slowing the fire down does not directly address your uneven temperatures, but it should help a lot by providing a more even consistent heat to the cook chamber.

 

[rbbennett]

I think you're on to something. even with the FB door open the flames are drawn into the cook chamber. Slowing the draft is definitely what it needs. I think the whole 20"diameter upright and the 6" stack are acting like a giant smokestack and really drawing hard. Opposite of most smokers I've had which had too little draw.

 

[Newglide]

I think you're on to something. even with the FB door open the flames are drawn into the cook chamber. Slowing the draft is definitely what it needs. I think the whole 20"diameter upright and the 6" stack are acting like a giant smokestack and really drawing hard. Opposite of most smokers I've had which had too little draw.

Wouldn't closing the damper on the smokestack have a similar affect, or you think it would hang out in the fat smokestack., not shamming your smokestack or anything