As one of the least common heating fuels, wood pellets are often misunderstood.
If you’re using wood pellets for heat, then you’re probably interested in their low cost, low emissions, and/or automatic stove fueling options.
Unfortunately, all of those benefits can be lost, if you buy bad pellets.
So in this post, we’re going to demystify wood pellet testing and selection.
We’ve broken it down into 3 sections:
- Appearance tests – which will help you choose pellets just by looking at them.
- Burn tests – which will help you further evaluate pellets, by burning a sample of them.
- Finding a reputable supplier – which will give you a start point, and examples of good pellet manufacturers.
Anybody can use the steps below, from the experienced home-heater, to folks who are hearing about pellets for the first time. Let’s get to it!
Easy appearance tests
You can learn a lot about the quality of pellets, simply by looking at them.
This is good news, because this is typically going to be your only option, when you’re at the store or seller location.
The best pellets, will have the following appearance qualities:
1. Smooth on the outside
Smooth, without frequent cracks or rough surfaces. This reveals a few things about the quality of the pellets.
First, it means that the manufacturer used the right “compression ratio”. I know, that sounds like something you’d hear in math class, but don’t freak out. You don’t need to memorize any numbers or equations.
Just know, that if the pellets are smooth and uniform on the outside, that the manufacturer did a good job with the compression process.
Better compression means your pellets are more dense, and will burn longer/hotter as a result.
In addition, a smooth outside surface points toward proper curing (i.e. drying) of the wood prior to compression.
Generally speaking, you want to shoot for a moisture level under 10%. That rating may or may not be listed, and so you can evaluate based on appearance.
If the wood pellets are crumbling, loose, or frequently cracked, then the wood was likely too wet when it was compressed. If you buy pellets in this condition, it will probably still burn, but will be much less efficient (and more expensive).
Given two bags of pellets of equal price, always go for the pellets that are better cured and compressed, which can be judged by examining their appearance.
2. Softwood pellets vs hardwood pellets
Even if you’re unable to identify trees, you will nearly always be able to tell the difference between hardwood and softwood pellets.
If you’re buying by the bag, it will say the wood type on the label. If you’re buying in bulk, you may still be able to read off a label. Or, if you trust the seller, just ask him/her.
In my mind, the most interesting topic when it comes to pellet heating, is hardwood vs. softwood pellets.
Here’s why: softwood pellets burn hotter than hardwood pellets.
This is completely different than normal firewood heating, in which hardwood (i.e. oak, hickory, etc.), is a far greater heat source than softwoods (i.e. pine, spruce, etc.).
As a result, folks who heat with wood pellets, tend to use softwood pellets during winter, and supplement with hardwood pellets in the warmer months.
As a pellet buyer, this is important to keep in mind, because an equal quantity of softwood pellets will produce more heat than hardwood pellets.
If you’d like a more comprehensive look at the differences between hardwood and softwood pellets, you can check out this post.
3. Pellet size
Generally, wood pellets will be around 1.15-1.5 inches long, and about 1/4 inch in diameter.
When purchasing pellets, don’t worry too much about the specific dimensions of the pellets. But keep two things in mind:
- A manufacturer’s pellets should be consistent – significant size differences from the same manufacturer is likely a sign that their equipment was improperly set-up. Not a good sign, if you’re looking for a long term supplier.
- If everything else is equal, buy smaller pellets – smaller pellets tend to feed into pellet stoves more smoothly, and it would be better to have pellets that are too small than too large.
When looking at pellet size, it’s also important to consider whether your stove has any specific size requirements.
Since pellet stoves can have a hopper, and automated systems to add more pellets, getting a size that’s not compatible with your stove can cause jams. Just something to keep in mind.
You can tell a lot through appearance, but there may be things you don’t notice right away.
Before buying in bulk, it’s probably best for you to buy a sample and test it.
Burn some of the pellets, and evaluate the following:
1. Flame color and scent
When wood pellets are burned, they should produce a flame just like you’d see from a typical wood fire.
If the flames have streaks of unusual colors like green or blue, then that could be a sign that additives were used.
Some manufacturers will add oils to help the pellets stick together, or to better lubricate the machinery.
Additives are not needed to create quality pellets, and you want to avoid them. They can reduce the heat output, while also increasing emissions.
If the pellets/fire smell bad, like sulfur or burning oil, that can also be a sign that additives were used during production.
2. Heat output
This probably goes without saying, but if you’re not satisfied with the heat output of your pellets, get something different.
Since heat output is impacted by a variety of circumstances (including your stove setup and airflow), it’s tough to tell exactly how well pellets will burn until you test them.
3. Ash produced
Another thing you want to avoid with your pellets, is impurities in the material. For example, low quality pellets might have bark and dirt mixed in.
This produces less heat, and burns dirtier, which means your stove would need cleaned more frequently.
Another side-effect of content impurities, are “clinkers”, which are leftover chunks of material (picture a lump of coal that won’t burn).
Generally speaking, the more pure your pellets are, the cleaner it will burn, and the less clinkers you’ll get.
You can test this simply by measuring the amount of ash produced after burning a sample of your new pellets.
According to the EPA, you want your ash content to be at least under 3%, and ideally it would be under 1%. Measuring this is easier than you’d think.
For example: if you burn 10 pounds (160 ounces) of pellets, and it produces 2 ounces of ash, then the ash content of those pellets is 2/160 = 1.25%
Finding a reputable supplier
Pellet Fuels Institute (PFI) Certification
The Pellet Fuels Institute is a 3rd party trade association, which serves as an authority on pellet material and manufacturing quality.
They provide ratings and standardized measures of pellet quality.
So,if you need a quick reference for manufacturers that are known to consistently produce quality pellets, then look for the PFI certification.
You can also go directly to the PFI website, to find a list of member manufacturers.
PFI does ongoing sampling, and quality testing, so purchasing from one of their member manufacturers can be a great way to save yourself time shopping around.
However, this won’t work for everyone. It’s a good start-point, but you may not have a PFI member manufacturer that serves your area, or you might have another supplier in mind already.
Examples of top brands
Examples can mean more than a million words, so here’s a few well-known pellet manufacturers you can use as a start point:
- Okanagan Pellet Company
- Vermont Wood Pellet Company
- Northern Warmth
At the end of the day, you’ll need to find a supplier that serves your geographic location.
So search for pellets that are supplied to your area, and then evaluate them for price and quality. Then stoke the flames of celebration.
There you have it.
If you want a start-point, use the above brand names, or CFI.
Plus, you now have some tricks you can use to compare wood pellets while you shop around, or by burning a sample batch.
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