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Northern Tool Heavy Duty Burner question...

defiant1

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I purchased the Heavy Duty burner from Northern Tool for my homemade propane smoker.  How do I adjust the three screws on the bottom of the burner to get a better flame? Any suggestions on the adjustments?

Any advice or practical experience is appreciated.

d1

 

defiant1

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Also, if it helps when supplying advice, I also installed a needle valve to help refine the flame/temperature.

d1
 

dirtsailor2003

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Don't have that "exact brand name one" but have one like it. I just use the little brass valves to set the flame. Nothing else. Straight shot to the tank.

Maybe your needle valve is the issue.
 

daveomak

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I purchased the Heavy Duty burner from Northern Tool for my homemade propane smoker.  How do I adjust the three screws on the bottom of the burner to get a better flame? Any suggestions on the adjustments?

Any advice or practical experience is appreciated.

d1
They may be air adjuster screws.....   They adjust to trim the flame from yellow to a clean blue flame...     Blue is what you want....   The adjusters are usually used at the setting you will use most because they don't deliver a linear adjustment over the full range of the burner...
 

defiant1

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Yes, the 3 air adjuster screws, how should they be adjusted? Closed, half way open, or removed? Just need a starting point.
 

daveomak

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Adjust the propane flow to a flame that looks like the right amount of gas flow for the heat range you want....  adjust the air screw until a clean blue flame is achieved with a small yellow tip for propane....

 

defiant1

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Good info. It will be a little time consuming to set. Every time I open the door to access the burner, 1/2 of the flame is yellow and the flames are about 3/4" high. Then when I crack the door just enough to peer in, the flame is blue with a very faint yellow tip and the flame is 3/8" high.

I guess that is why asked the original question, to help save time and effort.

d1
 

daveomak

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From what  you are describing, your smoking chamber has an air flow problem...

What is happening..... I've seen it....   with the door closed, the build up of heat and gasses, from the burner, is gathering inside the smoker...  eventually it works it's way to the air intake on the burner...   changing the air flow pattern..   the smoker is being filled and over flowing with oxygen depleted air from the burner...

Folks that build the cheap, run of the mill smokers build a box, throw in a burner and sell it....

So you built a home made gas fired smoker...   Sorry, I assumed it was store bought....   Don't kill yourself or someone else...

The flame should be exactly the same whether the door is open or closed...   The air intake, "venturi" portion of the burner assembly, should be outside the smoke chamber where it always has access to a fresh air supply...

If that "IS" the case, then the hot gasses are pressurizing the smoke chamber to "slow" the air flow through the burner....  thus changing the air / gas mix...

The dangerous part of this whole deal is....   If the flame should be extinguished because of any of the scenarios mentioned or others not mentioned, you could end up with a propane bomb should a spark or hot ember ignite the unburned fuel...
 
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daveomak

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Think about installing a flame out protection device or switch to electric.....
 

defiant1

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So do I need more air flow to the base of the burner when the door is closed? Is that what you are alluding to? Right now there is a 2" hole drilled on each side (left and right) at the bottom of smoker.
 

daveomak

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When the door closes, and the flame goes out, you do not have enough exhaust...  ,maybe even not enough intake...

Take pictures of the intakes and exhaust....
 

daveomak

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[h3]Propane Combustion Characteristics[/h3]

Lower Limit of Flammability
Upper Limit of Flammability
Flash Point
Ignition Temperature in Air
Maximum Flame Temperature
Octane Number

2.15
9.60
-156°F
920-1020°F
3595°F
Over 100
[h3]
Propane Combustion Characteristics Explained[/h3]
In order for propane to burn, ignite or go through combustion, the criteria listed above must be met. Below are explanations of propane gas combustion characteristics.

Propane Limits of Flammability - The lower and upper limits of flammability are the percentages of propane that must be present in an propane/air mixture. This means that between 2.15 and 9.6% of the total propane/air mixture must be propane in order for it to be combustible. If the mixture is 2% propane and 98% air, there will not be combustion. If the mixture 10% propane and 90% air, combustion will not occur. Any percentage of propane in a propane/air mixture between 2.15% and 9.6% will be sufficient for propane to burn. However, an improper air/gas mixture can produce Carbon Monoxide (CO) that is a deadly product of incomplete combustion.
Flash Point - The flash point is the minimum temperature at which propane will burn on its own after having been ignited. This number states that below -156°F, propane will stop burning on it's own. In other words, if the outside air temperature is -155°F, propane will burn on it's own. If the outside air temperature falls to -157°F, propane will no longer burn on it's own. However, if a source of continuous ignition is present, propane will burn below - 156°F.
Ignition Temperate in Air - This number states that propane will ignite if it reaches a temperature between 920-1020°F. If propane is heated up to a temperature between 920 and 1020°F, it will ignite without needing a spark or flame.
Maximum Flame Temperature - A propane flame will not burn hotter than 3595°F.
Octane Number - Without presenting a chemistry lesson, the Octane number of propane being over 100 means that it is a very engine friendly fuel.

Looking at the burner location and inlet sizes.....    I'm gonna guess.....    The incoming air is mixing with air that has already been burned and also mixing with wood burned air....   both are low in oxygen....   reducing the possibility of complete combustion of the propane gas...

I think the burner area needs to be isolated from all those combusted gasses for it to burn properly...    That can be done 2 ways...  cut a hole in the floor and lower the burner assembly until the burner ring is flush with the floor so it gets all fresh air from below....   or box in the burner assembly from the burner ring and expose the lower portion to outside air....   I do think the inlet air should be increased also...  

Whenever the possibility of already burned air can recirculate, it will screw up the possibility of a clean burn and possibly extinguish a flame or burning wood chips etc....
 

pete mazz

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Yea, you need to have the underside of the burner open to air for 2 reasons. One, as was said, the burner needs fresh air to burn clean. The other is that if the flame goes out, propane, being heavier than air, needs a way to get out of the cook chamber.

This is how I set mine up. The bolts are for the cast iron skillet I use for wood chunks. I have since changed burners as I couldn't get this one to keep a low enough temp.


This assembly was welded under the opening in the bottom of my smoker. It acts as a wind screen too.


Here it is in operation.

 

defiant1

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So if I create a "shelf" that is flush with burner ring, does the shelf have make contact on all four sides of the smoker? Or is a slight gap acceptable?
Thanks for taking time to post your advice.
d1


[h3]Propane Combustion Characteristics[/h3]


Looking at the burner location and inlet sizes.....    I'm gonna guess.....    The incoming air is mixing with air that has already been burned and also mixing with wood burned air....   both are low in oxygen....   reducing the possibility of complete combustion of the propane gas...
I think the burner area needs to be isolated from all those combusted gasses for it to burn properly...    That can be done 2 ways...  cut a hole in the floor and lower the burner assembly until the burner ring is flush with the floor so it gets all fresh air from below....   or box in the burner assembly from the burner ring and expose the lower portion to outside air....   I do think the inlet air should be increased also...  
Whenever the possibility of already burned air can recirculate, it will screw up the possibility of a clean burn and possibly extinguish a flame or burning wood chips etc....
[TR][TD][/td][/tr]
 
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daveomak

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Pete has the very best option ....   In the event of a flame out, you will not be creating a "propane bomb" of  your smoker cabinet...   Safety should be you first option...

Yea, you need to have the underside of the burner open to air for 2 reasons. One, as was said, the burner needs fresh air to burn clean. The other is that if the flame goes out, propane, being heavier than air, needs a way to get out of the cook chamber.
 

defiant1

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Understood. If I create a shelf with a hole cut out to accommodate burner ring and drill multiple holes in bottom of smoker to allow more air in, will that suffice?
 

pete mazz

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Air holes would probably be all you need. Convection should take care of the rest.
 
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