Pellet Fan
Accessories & Essentials => Pellets -- comments & questions => Topic started by: wahoowad on May 25, 2018, 07:11:24 AM
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I am surprised at the significant difference in temperature output and stability produced by using different brand pellets in my unit. When I first started using a pellet grill I suspected that all the pellets were the same...they mostly looked EXACTLY the same up close, exact same shape, length, just nothing to really separate one brand from another. But after trying a multitude of brands and styles I have proven to myself there certainly is a difference.
In my case something like Pit Boss Hickory produces consistently high temp swings of +50 and -50, often even more, and thick smoke. Similarly Camp Chef Comp Blend was nearly as bad, just a tad less so but still not suitable in my unit for stable low and slow smoking. Finally I obtained some Lumberjack Cherry and Lumberjack CharHickory and both allowed the unit to operate within acceptable swings (+/- 25, usually less).
So what is different between all these different brands? Fillers or binders that add to the combustion characteristics?
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Most wood species have nearly the same BTU/lb so it could be water content.
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All woods are not created equally. Take the following as a 'guideline' for pellet cooking. There are many variables involved, but this will get you started on yer journey.
http://worldforestindustries.com/forest-biofuel/firewood/firewood-btu-ratings/
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All woods are not created equally. Take the following as a 'guideline' for pellet cooking. There are many variables involved, but this will get you started on yer journey.
http://worldforestindustries.com/forest-biofuel/firewood/firewood-btu-ratings/
Not really. That chart is for firewood by volume (cord) and is very deceiving when considering pellets. BTU for different species can vary quite a bit by volume. But once ground up and pressed into pellets, everything changes. For example, softwood like Doug Fir looks like it has much lower BTU than Live Oak. But buy the lb, Fir has 8617 BTU compared to 7561 for oak.
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All woods are not created equally. Take the following as a 'guideline' for pellet cooking. There are many variables involved, but this will get you started on yer journey.
http://worldforestindustries.com/forest-biofuel/firewood/firewood-btu-ratings/
Not really. That chart is for firewood by volume (cord) and is very deceiving when considering pellets. BTU for different species can vary quite a bit by volume. But once ground up and pressed into pellets, everything changes. For example, softwood like Doug Fir looks like it has much lower BTU than Live Oak. But buy the lb, Fir has 8617 BTU compared to 7561 for oak.
Then there is the compression factor. Some pellet mills are able to compress more wood into the same diameter pellet resulting in higher BTUs per pound.
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Last week I was preparing the DC for searing a sous vide chuck roast, I set the temperature to 525 and checked the pellets. There were very few Pit Boss pellets left so I grabbed the next bag in my stack which happened to be Traeger apple wood blend. I filled the hopper and let the DC do its thing. When the temp. reached 510 and I put the roast on to sear for a few minutes, then I noticed that the temp. was falling. Before the sear was complete, the temp. had fallen to 425. I attribute the temp. reduction to the Traeger apple/alder pellets. IMO, pellets can make a big difference in amount of heat produced. From the above chart, apple/alder produce almost half the BTUs of oak. :2cents:
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>Then there is the compression factor. Some pellet mills are able to compress
>more wood into the same diameter pellet resulting in higher BTUs per pound.
John, you need to go back and finish your coffee :)
The amount of compression would not affect btu per pound. It would affect the amount of BTU per volume.
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I just finished my coffee. Thanks.
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> From the above chart, apple/alder produce almost half the BTUs of oak.
Hugh, that chart has little to no bearing on pellets until you convert it into BTU/lb - it's made for cord wood which is a volume measurement. It may surprise many that species with the highest BTU's/lb are softwoods like pine, fir and spruce.
According to that chart, by the pound, apple wood actually has MORE BTU than white and red oak. I think many folks are confusing BTU with temperature. BTU is a unit of heat energy. You can have 2 different pellets; one that burns cooler and slower, and the other that burns hotter and faster, but both have the same BTU. In a pellet grill with a good controller, it doesn't really matter and both pellets will provide the same amount of energy. With grills that have a hard time maintaining high temps, or if you are running in a non temp controlled mode, then a pellet that burns hotter (but faster) may give better results.
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Here's that same chart Bobitis posted, but converted to BTU/LB. Hope this image is legible.
Note: Click on the image to enlarge it.
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I think that the DC was providing all of the apple/alder pellets that it could but could not achieve the set temperature. Either that or my controller is failing ;D.
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Tough to read but using "control-plus" enlarges it to a marginally readable size.
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I just click on the image and it gets bigger and much easier to read.
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Last week I was preparing the DC for searing a sous vide chuck roast, I set the temperature to 525 and checked the pellets. There were very few Pit Boss pellets left so I grabbed the next bag in my stack which happened to be Traeger apple wood blend. I filled the hopper and let the DC do its thing. When the temp. reached 510 and I put the roast on to sear for a few minutes, then I noticed that the temp. was falling. Before the sear was complete, the temp. had fallen to 425. I attribute the temp. reduction to the Traeger apple/alder pellets. IMO, pellets can make a big difference in amount of heat produced. From the above chart, apple/alder produce almost half the BTUs of oak. :2cents:
You do know that Traeger uses 'flavored oils' to make pellets? In the East they use oak as the base. In the West they use alder. They add oils that flavors the wood.
Enuff said, it's Traeger. Discuss................................. Real wood flavor vs 'oils'.
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It only happened to me once, it was a pellet that a manufacture sent to me. I am pretty sure they never came to market. It just wade the DB wonky, would not perform well at all. Only time I have ever seen it happen though. Never had any issues with "main stream" pellets in the DB or the Memphis Pro!
I am surprised at the significant difference in temperature output and stability produced by using different brand pellets in my unit.
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My belief is the two biggest factors you will see when buying a bag of pellets are:
A) Moisture content. This will vary buy several percentage points and since you are buying by weight, the higher water content, the less wood you will get per bag. Also, chances are the higher moisture content will also lower your burn temperature or increase the amount of pellets you will use.
B) Ash content. Ash doesn't burn. The higher non-burnable product you have (non-flammable impurities) the more non-burnable wood you will have in a bag of pellets.
Some math:
Gas grills can range from 35,000 BTU per hour to 50,000+.
For ease of math, we'll say we are running our pellet grills for an hour at a temperature that makes us use 24,000 BTU per hour.
To get the 24,000 per hour you would need the following amount of flammable wood to get 24,000 BTU in that hour.
A 6,000 BTU wood = 4 lbs
A 7,000 BTU wood = 3.5 lbs
A 8,000 BTU wood = 3 lbs of flammable wood burned.
If you 8,000 BTU wood was at 15% ash and moisture (total combined), you're using close to 3.5 lbs of pellets.
Also, if your moisture percentage will be 8% or less, so you have less water in your burn which would affect temperature differences between two similar woods.
It's unknown what an additional 7% of water / ash will do to a fire, but my assumption is that it would burn cooler / use more pellets.
PFI certifies pellet fuels on moisture and ash where bbq pellets are unregulated so you don't really know what you are getting since they aren't tested.
From using both, I've seen from my own experience the massive reduction in ash and less pellet usage from burning PFI certified pellets (not to mention the much lower cost).
If I want a specific smoke flavor, I use a smoke tube with a few ounces of bbq pellets rather than burn pounds and pounds of them as a heat source.
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Even if different pellets produced more or less heat that could lead to some temp swings but not an overall higher or lower temp as that is what the controller in a pellet smoker is for right? I mean, lets say you ran a "hot pellet". Set point is 225. Feeds in pellets at a set rate based on the controller. Oops temp jumps due to "hot pellet". So controller stops feed, temp, falls, repeat. The opposite would happen with a "cool burning pellet". But either way the difference can't possibly be that significant given how tight some of these controllers are.
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Even if different pellets produced more or less heat that could lead to some temp swings but not an overall higher or lower temp as that is what the controller in a pellet smoker is for right? I mean, lets say you ran a "hot pellet". Set point is 225. Feeds in pellets at a set rate based on the controller. Oops temp jumps due to "hot pellet". So controller stops feed, temp, falls, repeat. The opposite would happen with a "cool burning pellet". But either way the difference can't possibly be that significant given how tight some of these controllers are.
That would depend on the controller. Digital - yes. PID - no.
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My belief is the two biggest factors you will see when buying a bag of pellets are:
A) Moisture content. This will vary buy several percentage points and since you are buying by weight, the higher water content, the less wood you will get per bag. Also, chances are the higher moisture content will also lower your burn temperature or increase the amount of pellets you will use.
B) Ash content. Ash doesn't burn. The higher non-burnable product you have (non-flammable impurities) the more non-burnable wood you will have in a bag of pellets.
Some math:
Gas grills can range from 35,000 BTU per hour to 50,000+.
For ease of math, we'll say we are running our pellet grills for an hour at a temperature that makes us use 24,000 BTU per hour.
To get the 24,000 per hour you would need the following amount of flammable wood to get 24,000 BTU in that hour.
A 6,000 BTU wood = 4 lbs
A 7,000 BTU wood = 3.5 lbs
A 8,000 BTU wood = 3 lbs of flammable wood burned.
If you 8,000 BTU wood was at 15% ash and moisture (total combined), you're using close to 3.5 lbs of pellets.
Also, if your moisture percentage will be 8% or less, so you have less water in your burn which would affect temperature differences between two similar woods.
It's unknown what an additional 7% of water / ash will do to a fire, but my assumption is that it would burn cooler / use more pellets.
PFI certifies pellet fuels on moisture and ash where bbq pellets are unregulated so you don't really know what you are getting since they aren't tested.
From using both, I've seen from my own experience the massive reduction in ash and less pellet usage from burning PFI certified pellets (not to mention the much lower cost).
If I want a specific smoke flavor, I use a smoke tube with a few ounces of bbq pellets rather than burn pounds and pounds of them as a heat source. Right on brother..
My belief is the two biggest factors you will see when buying a bag of pellets are:
A) Moisture content. This will vary buy several percentage points and since you are buying by weight, the higher water content, the less wood you will get per bag. Also, chances are the higher moisture content will also lower your burn temperature or increase the amount of pellets you will use.
B) Ash content. Ash doesn't burn. The higher non-burnable product you have (non-flammable impurities) the more non-burnable wood you will have in a bag of pellets.
Some math:
Gas grills can range from 35,000 BTU per hour to 50,000+.
For ease of math, we'll say we are running our pellet grills for an hour at a temperature that makes us use 24,000 BTU per hour.
To get the 24,000 per hour you would need the following amount of flammable wood to get 24,000 BTU in that hour.
A 6,000 BTU wood = 4 lbs
A 7,000 BTU wood = 3.5 lbs
A 8,000 BTU wood = 3 lbs of flammable wood burned.
If you 8,000 BTU wood was at 15% ash and moisture (total combined), you're using close to 3.5 lbs of pellets.
Also, if your moisture percentage will be 8% or less, so you have less water in your burn which would affect temperature differences between two similar woods.
It's unknown what an additional 7% of water / ash will do to a fire, but my assumption is that it would burn cooler / use more pellets.
PFI certifies pellet fuels on moisture and ash where bbq pellets are unregulated so you don't really know what you are getting since they aren't tested.
From using both, I've seen from my own experience the massive reduction in ash and less pellet usage from burning PFI certified pellets (not to mention the much lower cost).
If I want a specific smoke flavor, I use a smoke tube with a few ounces of bbq pellets rather than burn pounds and pounds of them as a heat source.
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Even if different pellets produced more or less heat that could lead to some temp swings but not an overall higher or lower temp as that is what the controller in a pellet smoker is for right? I mean, lets say you ran a "hot pellet". Set point is 225. Feeds in pellets at a set rate based on the controller. Oops temp jumps due to "hot pellet". So controller stops feed, temp, falls, repeat. The opposite would happen with a "cool burning pellet". But either way the difference can't possibly be that significant given how tight some of these controllers are.
That would depend on the controller. Digital - yes. PID - no.
Can you elaborate. Did you mean analog vs. PID? I thought PID controllers were inherently digital.
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Even if different pellets produced more or less heat that could lead to some temp swings but not an overall higher or lower temp as that is what the controller in a pellet smoker is for right? I mean, lets say you ran a "hot pellet". Set point is 225. Feeds in pellets at a set rate based on the controller. Oops temp jumps due to "hot pellet". So controller stops feed, temp, falls, repeat. The opposite would happen with a "cool burning pellet". But either way the difference can't possibly be that significant given how tight some of these controllers are.
Right. The hotter burning pellet would use less pellets because the controller will slow down the auger and feed less pellets.
That's why I see less pellet usage, (probably due to less moisture) and way less ash, when using heating pellets over BBQ pellets.
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Even if different pellets produced more or less heat that could lead to some temp swings but not an overall higher or lower temp as that is what the controller in a pellet smoker is for right? I mean, lets say you ran a "hot pellet". Set point is 225. Feeds in pellets at a set rate based on the controller. Oops temp jumps due to "hot pellet". So controller stops feed, temp, falls, repeat. The opposite would happen with a "cool burning pellet". But either way the difference can't possibly be that significant given how tight some of these controllers are.
That would depend on the controller. Digital - yes. PID - no.
Can you elaborate. Did you mean analog vs. PID? I thought PID controllers were inherently digital.
A PID is analog. Proportional, Integral, and Derivative controllers go back 100+ years in industry. Long before digital computers existed. Today's PID controllers use a digital computer that simulates the PID functions. The functions themselves are still analog in nature.
There may also be a digital display of the temperature, and some manufactures use the term "Digital" to describe that.
There are other algorithms that are purely digital, and do not mimic the PID functions. I am not an expert on these, but I do know they exist. I think some pellet grills may use these purely digital algorithms. I suspect when a manufacturer states that the controller is digital and uses something other than PID, that this is what they use.