What is the best calculator to use for a reverse flow build
- Thread starter lovelife
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I adjusted the bottom of my smokestack and it this is what it looks like now:
I did a test run after. I got my temp up to 270F in an hour (used more charcoal to start off with compared to last time). At both the top right and top left shelf I had two thermometers. One of the left side of the shelf, the other on the right side. So 4 in total.
The measurements looked like this:
297F.....270F - 270F.....270F
So pretty even except for the thermometer closest to the smokestack. It seems like there is a hotspot and smoke is not being able to escape fast enough....would you agree with that conclusion? Would it be best to drill another hole for smoke to escape? Any other ideas?
I did a test run after. I got my temp up to 270F in an hour (used more charcoal to start off with compared to last time). At both the top right and top left shelf I had two thermometers. One of the left side of the shelf, the other on the right side. So 4 in total.
The measurements looked like this:
297F.....270F - 270F.....270F
So pretty even except for the thermometer closest to the smokestack. It seems like there is a hotspot and smoke is not being able to escape fast enough....would you agree with that conclusion? Would it be best to drill another hole for smoke to escape? Any other ideas?
When you get meat in the smoker, all that will change as the flow pattern will change also... You might find another "hot spot" that you can use to your advantage.... I would cook on it a few times and see what happens... ALSO, did you check the calibration of the thermometers ?? They could be different...
And that difference I wouldn't worry about...
And that difference I wouldn't worry about...
Hi Dave,
Yeah my thermometers were calibrated, thanks for the reminder though.
The difference throughout the first hour of the smoker warming up was between 30-40F. I will check it out next few smokes...40F or more would be a significant difference, right?
I dropped smoker off at a company who is going to sandblast and paint it black. Will post pictures when done.
Yeah my thermometers were calibrated, thanks for the reminder though.
The difference throughout the first hour of the smoker warming up was between 30-40F. I will check it out next few smokes...40F or more would be a significant difference, right?
I dropped smoker off at a company who is going to sandblast and paint it black. Will post pictures when done.
Top rack - back.
However I have not measured the Temps yet at the front side. In the middle of my test run something came up and I had to abort the session. I'm going to do an extensive test session when I have my smoker back. Top rack, bottom rack, front, middle, back.
After that session I'm going to seal the doors to see what % of smoke and heat I was leaking. I will report back.
However I have not measured the Temps yet at the front side. In the middle of my test run something came up and I had to abort the session. I'm going to do an extensive test session when I have my smoker back. Top rack, bottom rack, front, middle, back.
After that session I'm going to seal the doors to see what % of smoke and heat I was leaking. I will report back.
OH, you haven't sealed the doors.... that explains a lot... Stop testing until the doors are sealed....
I'm far from an expert in airflow so it does not explain anything to me :) I'm really curious to know what it explains to you though. I just know that smoke is leaking through to the edges of the doors...how does that effect the temp contribution throughout the smoker? I want to learn.
How are the FB dampers adjusted when all this is happening.... How big is the fire... How much wood.... how much coals...
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Dampers were fully open.
The fire was 1.5 chimney starter full of coals and about 5 pieces of these size wood logs: https://www.google.nl/search?q=wood...AUIBygB&biw=360&bih=559#imgrc=9IRrJB7hlzoXeM:
The fire was 1.5 chimney starter full of coals and about 5 pieces of these size wood logs: https://www.google.nl/search?q=wood...AUIBygB&biw=360&bih=559#imgrc=9IRrJB7hlzoXeM:
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Just to clarify. What temp was it at when the doors were leaking? When a smoker is cold it will often leak at the doors as the chimney is not hot enough to create a draft to suck out the smoke. I looked through the old posts on the thread but can;t see what length chimney you ended up with and if you have anything on top of it restricting flow.
You can always easily cut the excess pipe off the inside of the smoker to see if that makes a difference. Maybe invest in a laser thermometer to measure grate temps more accurately when checking for hotspots or use the old white bread on the grates trick.
You can always easily cut the excess pipe off the inside of the smoker to see if that makes a difference. Maybe invest in a laser thermometer to measure grate temps more accurately when checking for hotspots or use the old white bread on the grates trick.
Did you try closing down the lower air inlet on the FB... leave the upper wide open...
How long did this test go.... 15 minutes.... 1/2 hour.... Sounds like the smoker didn't get up to temp... OR... there is an air flow problem....
You might plug those holes drill into the exhaust stack inside the cook chamber... they could be interrupting the exhaust gas air flow... a piece of sheet metal wired over them or use a hose clamp...
It would be nice to know everything about this test burn so an informed conclusion "might" be able to be made...
Pictures tell a lot.... pictures of how the vents were.... pictures of the fire.... pictures of the wood grate and it's location inside the FB....
What did you end up with for an exhaust stack... Is it 7"...
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post #35 of 70
4/20/16 at 4:01pm
Use 2 each 5" stacks.... in place of the one 7" stack same thing.... 5" = 19.6 sq. inches... 7" = 38.5 square inches...
How long did this test go.... 15 minutes.... 1/2 hour.... Sounds like the smoker didn't get up to temp... OR... there is an air flow problem....
You might plug those holes drill into the exhaust stack inside the cook chamber... they could be interrupting the exhaust gas air flow... a piece of sheet metal wired over them or use a hose clamp...
It would be nice to know everything about this test burn so an informed conclusion "might" be able to be made...
Pictures tell a lot.... pictures of how the vents were.... pictures of the fire.... pictures of the wood grate and it's location inside the FB....
What did you end up with for an exhaust stack... Is it 7"...
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post #35 of 70
4/20/16 at 4:01pm
- DaveOmak
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Use 2 each 5" stacks.... in place of the one 7" stack same thing.... 5" = 19.6 sq. inches... 7" = 38.5 square inches...
@Ahumadora thanks for your message.
The doors leak at all times. If I remember correctly the smokestack is 38 inches above the CC. Will have to measure it when I get my smoker back to be sure though.
Cutting off the pipe on the inside...there is a large group of people who don't like to have the smokestack start at the top of the smoker. There is also a group of people who prefer the stack to start at the top of the tank. It's too early for me to change things around yet...so I'll wait with that until I did some more testing. Thanks for sharing the thought though!
I will look into the white bread trick :)
The doors leak at all times. If I remember correctly the smokestack is 38 inches above the CC. Will have to measure it when I get my smoker back to be sure though.
Cutting off the pipe on the inside...there is a large group of people who don't like to have the smokestack start at the top of the smoker. There is also a group of people who prefer the stack to start at the top of the tank. It's too early for me to change things around yet...so I'll wait with that until I did some more testing. Thanks for sharing the thought though!
I will look into the white bread trick :)
Sorry Dave missed your post.
Did you try closing down the lower air inlet on the FB... leave the upper wide open...
How long did this test go.... 15 minutes.... 1/2 hour.... Sounds like the smoker didn't get up to temp... OR... there is an air flow problem....
You might plug those holes drill into the exhaust stack inside the cook chamber... they could be interrupting the exhaust gas air flow... a piece of sheet metal wired over them or use a hose clamp...
It would be nice to know everything about this test burn so an informed conclusion "might" be able to be made...
Pictures tell a lot.... pictures of how the vents were.... pictures of the fire.... pictures of the wood grate and it's location inside the FB....
What did you end up with for an exhaust stack... Is it 7"...
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post #35 of 70
4/20/16 at 4:01pm
- DaveOmak
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Use 2 each 5" stacks.... in place of the one 7" stack same thing.... 5" = 19.6 sq. inches... 7" = 38.5 square inches...
Will make all the pictures requested during my next test.
I just picked up my smoker and of course they did something not requested :) They painted the inside too. The paint they used is heat proof up to 1650F. Will that cause any issues?
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