# Northern Tool Heavy Duty Burner question...



## defiant1 (Jul 18, 2016)

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













single heavy duty burner.jpg



__ defiant1
__ Jul 18, 2016


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## defiant1 (Jul 19, 2016)

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

d1


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## dirtsailor2003 (Jul 20, 2016)

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.


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## daveomak (Jul 20, 2016)

defiant1 said:


> 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...


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## defiant1 (Jul 20, 2016)

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


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## daveomak (Jul 20, 2016)

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....













FLAME adjustment.png



__ daveomak
__ Jul 20, 2016


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## defiant1 (Jul 20, 2016)

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


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## daveomak (Jul 20, 2016)

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 (Jul 20, 2016)

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


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## defiant1 (Jul 29, 2016)

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.


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## daveomak (Jul 29, 2016)

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....


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## tjmitche (Jul 30, 2016)

Watching


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## defiant1 (Jul 31, 2016)

DaveOmak said:


> 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....















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__ Jul 31, 2016


















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__ Jul 31, 2016


















20160731_191623.jpg



__ defiant1
__ Jul 31, 2016


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## daveomak (Jul 31, 2016)

[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....


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## pete mazz (Aug 1, 2016)

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.













Burner-Installed.jpg



__ pete mazz
__ Aug 1, 2016






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













Burner-Assembly.jpg



__ pete mazz
__ Aug 1, 2016






Here it is in operation.













First-Smoke.jpg



__ pete mazz
__ Aug 1, 2016


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## defiant1 (Aug 1, 2016)

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




DaveOmak said:


> [h3]Propane Combustion Characteristics[/h3]
> 
> 
> 
> ...




[TR][TD][/td][/tr]


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## daveomak (Aug 1, 2016)

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._


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## defiant1 (Aug 1, 2016)

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?


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## pete mazz (Aug 1, 2016)

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


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## defiant1 (Aug 1, 2016)

Pete Mazz said:


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



I will try drilling new holes first. Is there such a thing as having too much air intake (aside from strong winds)?


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## daveomak (Aug 1, 2016)

Drilling new holes in the current configuration still leaves you with a possible propane bomb.....  But, do what you wish.....  We can't force you to do things in a safe manner, only point out the deficiencies in your design...  Install a flame sensor so the propane shuts off when the flame goes out....

*Man killed when meat smoker explodes*

Colleen Kottke, The (Fond du Lac, Wis.) Reporter 4:49 p.m. EST December 15, 2014

(Photo: The (Fond du Lac, Wis.) Reporter)

TOWN of LAMARTINE, Wis. — A Wisconsin man using a homemade meat smoker to cook turkeys and chickens died when the smoker exploded, police said.

Richard L. Zabel, 55, was found dead Saturday afternoon inside a machine shed.

"The North Fond du Lac Ambulance and Lamartine first responders were called to the scene for the initial report that someone had fallen," said Lt. Cameron McGee of the Fond du Lac County Sheriff's Office. "When investigators arrived on scene, they discovered that a 55-year-old man was dead inside the building."

Zabel, a town of Lamartine man, did not live at the building's location, but lived nearby.

"Evidence indicates that the flame on the LP burner went out and as a result the gas continued to accumulate inside the smoker," McGee said. "And when (Zabel) went to relight the burner, the spark from the lighter caused the gas to explode."

McGee said the force of the explosion caused the heavy duty door of the smoker to blow open, striking Zabel in the head, killing him instantly.

"When something explodes, it's going to blow open at the weakest point which was the door, which was triple-latched," McGee said.

McGee said the smoker was larger and better constructed than most store-bought models.

"It was about 4-feet tall and about 3-feet wide and built really solid, including the door. Someone really put a lot of thought into building this thing," McGee said. "We were told that they had been using it for the past three years without any problems."

The Fond du Lac County Sheriff's Office is investigating the incident.


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## defiant1 (Aug 1, 2016)

DaveOmak said:


> Drilling new holes in the current configuration still leaves you with a possible propane bomb.....  But, do what you wish.....  We can't force you to do things in a safe manner, only point out the deficiencies in your design...  Install a flame sensor so the propane shuts off when the flame goes out....


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## pete mazz (Aug 2, 2016)

Well, I wouldn't want the entire bottom of the smoker open...
	

	
	
		
		



		
			






 Gas smokers are no more dangerous than a gas grill. Common sense goes a long way, but you can blow yourself up with either.

If you're going to use holes, make them decent size. 2" or more would work. Or make something like a 6" opening below the burner.


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## defiant1 (Aug 2, 2016)

Pete Mazz said:


> Well, I wouldn't want the entire bottom of the smoker open...:icon_biggrin:  Gas smokers are no more dangerous than a gas grill. Common sense goes a long way, but you can blow yourself up with either.
> 
> If you're going to use holes, make them decent size. 2" or more would work. Or make something like a 6" opening below the burner.



I drilled one 3" hole under the burner last night.  It seemed to help.  If I drill more holes, do you recommend openings in the floor or sides?


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## hillbilly jim (Aug 2, 2016)

My Masterbuilt 44 inch has a 9.78 cubic foot cabinet. The 'as built' hole in the bottom is 8" X 14". That's 112 square inches. The exhaust flue I installed in the top is 6 inches in diameter. That's 28 square inches, one quarter of the bottom opening. I can throttle the exhaust by means of the damper I installed in the flue.

I'm just sayin'.....


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## defiant1 (Aug 2, 2016)

Hillbilly Jim said:


> My Masterbuilt 44 inch has a 9.78 cubic foot cabinet. The 'as built' hole in the bottom is 8" X 14". That's 112 square inches. The exhaust flue I installed in the top is 6 inches in diameter. That's 28 square inches, one quarter of the bottom opening. I can throttle the exhaust by means of the damper I installed in the flue.
> 
> I'm just sayin'.....



Compared to your smoker, my setup is definitely lacking air intake.  I currently have one 3" hole and two 2" holes.  The exhaust openings are two 6" holes. Do you happen to know the appropriate ratio for intake to exhaust?  Thanks for your reply.


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## hillbilly jim (Aug 2, 2016)

No Sir, can't help you with any ratios.

I installed the 6 inch flue in top of my smoker because the original vents only equated to a 2, 1/2" diameter hole. Not NEARLY enough. I put a damper in the flue so I could choke it if I wanted. That has paid off as there have been situations where a wide open 6 inch flue was too much exhaust.

When fuels gas is burned, the cubic feet of exhaust is greater than the combined cubic feet of air and fuel gas prior to ignition. I would rather have a bigger inlet to avoid starving the fuel of air.  And, with a nice big exhaust outfitted with a damper, you can always choke it down for whatever reason.


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## pete mazz (Aug 2, 2016)

With the burner you have the air intakes are inside the CC with the burner. If you look at mine, combustion gas and air is supplied at the rear of the burner which is open to air. You need to make sure your burner is getting plenty of air so I would drill more holes in the bottom, near the gas inlets. Better yet would be to section it off from the CC entirely.


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## defiant1 (Aug 9, 2016)

Pete Mazz said:


> With the burner you have the air intakes are inside the CC with the burner. If you look at mine, combustion gas and air is supplied at the rear of the burner which is open to air. You need to make sure your burner is getting plenty of air so I would drill more holes in the bottom, near the gas inlets. Better yet would be to section it off from the CC entirely.



Ok I installed a shelf surrounding the burner (I cut a hole for the burner).  It is not 100% sealed off from the CC, as there is a gap between the shelf and door.  I also drilled three 3" holes in the floor under the burner.

I started burning propane and got it up to temperature and regulated the flame height with the needle valve.  It seemed to work well.  

I did have an observation though.  With my old burner setup the temperature at the top of the CC was about 5-7 degrees higher than the lower portion of the CC.  With my new burner/setup, the top portion of the CC is 5-7 degrees cooler than the lower portion.

Any ideas on why there was a change?

d1


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## daveomak (Aug 9, 2016)

Switch the therms position...   the therms aren't reading the same...


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## pete mazz (Aug 9, 2016)

I wouldn't worry about 5 or 10 degrees difference anyway.


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