Heat output vs pellet size/length

[Rooscooter]

I've been reading a lot of posts regarding heat output for each type/brand of pellet out there and wanted to add my experience to the discussion.

I've been burning pellets for over 10 years and have noticed that the heat output of my stoves varies depending on what pellet is used (duh). I used to think this is just the difference in pellet brands, however recently I had some extra time on my hands and decided to test and see what difference there is in the brands that I have stored for this winter.

This year I had 4 tons of pellets delivered and stored for my 2 Bosca Spirit 500 stoves. 1 ton is Atlas Ultra Premium Red Fir, 1 ton is North Idaho Energy Premium and the other 2 are Westwood Premium (which are re-branded Okanagan Pellets from B.C.). All of these brands are softwood pellets and are considered the best available in our area.

Using a thermometer (procedure similar to one I saw on this forum) I tested each pellet in a clean stove one bag at a time. I tested heat, ash and time it took to burn the entire bag. I used the 3rd highest of the 4 settings on my stove for the test. Here's what I got:

Westwood Premium: 265° and 12hr 18 min burn time (second lowest ash no clinkers)
North Idaho Pellets: 252° and 13hr 53 min burn time (lowest ash by far no clinkers)
Atlas Ultra Premium: 248° and 13hr 22 min burn time (highest ash no clinkers)

The burn time of the Westwoods jumped out at me and made me burn a second bag to make sure I didn't make a mistake. The time for the second bag was within a few minutes of the first bag (the time above is the average of the two).

After looking at the pellets themselves I found out why the Westwoods were both the hottest and had the shortest burn time. The pellet length is very short compared to the other two brands. Also they are very consistent in length. The short and uniform length allows more consolidation both in the hopper and in the auger allowing a higher volume of pellets to fall into the burn pot per revolution of the auger. I further confirmed this when measured the "high water mark" in the hopper when loading a single bag of each brand. The hopper was almost 2" "more full" with the North Idaho and Atlas pellets than with the Westwoods.

So while there is definitely a heat output difference that is dependent on quality of material used, there seems to be a direct correlation to size of pellet as well........at least in my less than scientific test.

 

[tjnamtiw]

Well done! That took patience. I am burning another brand from my crappy Carolina Wood Pellets, that have lengths varying from 3"+ down to 'pebble' size. The latest brand is Greenway, made in Tennessee. I read a lot of negatives on these but so far, they seem much better. They are very dense compared to CWP and the lengths are short and consistent, which gives me a nice, consistent feed rate. Before with the CWP's, the fire would go from embers to flames to the top plate as the feed rate varied. Now I have much more control and the heat seems better although I haven't measured it (shame on me since I have a 'baseline').
I think you are right in your assumptions about pellet length!

 

[jtakeman]

Well done Rooscooter, Nice experiment!

I am burning another brand from my crappy Carolina Wood Pellets, that have lengths varying from 3"+ down to 'pebble' size. The latest brand is Greenway, made in Tennessee. I read a lot of negatives on these but so far, they seem much better. They are very dense compared to CWP and the lengths are short and consistent, which gives me a nice, consistent feed rate. Before with the CWP's, the fire would go from embers to flames to the top plate as the feed rate varied. Now I have much more control and the heat seems better although I haven't measured it (shame on me since I have a 'baseline').
I think you are right in your assumptions about pellet length!

I was burning O Malleys leftover from last season. They also had very long pellets in the mix. You could hear the auger struggle to break them when it was feeding. Flame was very inconsistent. I took a bag and broke all the pellets(one at a stinking time) to no longer than 1/2 in length. I tossed them in at the same feed rate as the others. The flame grew and I had to turn the feed trim down some. Temps for the untouched batch was about 235ºF. Temps for the sized batch was 248ºF.

Try this and see if it helps the CWP with the inconsistent flame height.

 

[Rooscooter]

[/quote]Interesting........I wonder how much your results would vary, if you were to knock back your auger setting to one lower, how that would effect the results with a slower feed rate? on the Westwoods. (They are only available in the West)[/quote]

I haven't tried to monkey with the auger settings. The goal of my "research" was to determine which pellets were putting out the most heat.

In the end I found out that there isn't a lot of difference in the these pellets as far as material. The difference is in the quality and consistency of milling. The Westwood pellets are very uniform in size, seem harder (no subjective evidence just feel) and are much shorter than the other two. This results in less opportunity for auger jams.

Next year I will probably consolidate my pellet store to just the North Idaho and Westwood pellets.......that is if I can still find the Westwoods in Spokane.

 

[Rooscooter]

Interesting........I wonder how much your results would vary, if you were to knock back your auger setting to one lower, how that would effect the results with a slower feed rate? on the Westwoods. (They are only available in the West)

I haven't tried to monkey with the auger settings. The goal of my "research" was to determine which pellets were putting out the most heat.

In the end I found out that there isn't a lot of difference in the these pellets as far as material. The difference is in the quality and consistency of milling. The Westwood pellets are very uniform in size, seem harder (no subjective evidence just feel) and are much shorter than the other two. This results in less opportunity for auger jams.

Next year I will probably consolidate my pellet store to just the North Idaho and Westwood pellets.......that is if I can still find the Westwoods in Spokane.[/quote]

No reason why you shouldn't (or at least Okies) as this has proven to a very large market area for us and the pellet has been very well received there. If you have any trouble, let me know and I will point you in the right direction.....[/quote]

Earlier in the year I e-mailed your company looking for Okanagan Pellets in the Spokane area and got a response that there were two outlets locally for Westwood Pellets. Only one of the listed outlets had any left. The person responding didn't list any outlets for Okanagan Pellets.