"Caking" of partially burned pellets

[LRRifleman]

Hello!

I do not know if I have a problem or not, or if I have a problem in my "logic" on this issue.

Of late, I have "fired up" my pellet stove to take the chill off of damp days and chilly nights, but shut the stove down on the warmer days. I am burning "Lignetics" pellets that are kept dry, and do not show any "swelling" due to excessive moisture content. The problem is, after the second or third "shutdown" as described above, the unburned pellets are caking up in the fire pan. It is my belief, that if their is an excessive moisture content in the pellets, this moisture would evaporate when the stove is burning. My concern is, I do not understand why this "caking" is occuring, and am apprehensive about this "caking" since this is a manual replication of what I anticipate would happen once I attach a thermostat to the stove to control the burn for the winter. When the "caking" of partially burned pellets occurs, it s not uncommon for the build-up to "suffocate" the fire in the fire pan.

My question: how do I combat this buildup of unburnt/partially burnt pellets?

 

[CJ-SR4ever]

What stove are you running?

 

[Don2222]

Hello

Well you are quite correct that the moisture is causing the caked ash. I have definitely found that to be true!!

The question is where is it coming from and how can you prevent it?

It can becoming from only 1 or 2 sources, either the wood pellets or the intake air to the burn pot.

So by process of elimination:

1. Are the pellets you purchased good and dry? You have stated this is so.

2. Are the pellets at room temperature before you burn them?
I had mine in a very cold garage and had caked ash if I dumped them right into the pellet stove.
The quick heat up causes condensation.

3. Is your stove in a damp or musty basement and bringing that damp air into the burn pot?
Use an OAK (Outside Air Intake)

4. If you are using an OAK
In the shoulder seasons especially on damp days, cool damp air going into the burn pot will produce caked ash on the low heat settings. Using a higher heat setting on your wood pellet stove will help.

Travis Ind has solved this issue for low temp settings with a small 1" rectangular cut into the left side of the Intake Air Plenum that pulls warm room air and further heats it inside the stove and then to feed the burn pot.

So that is about it! What make and model is your stove?

 

[LRRifleman]

1) Yes, the pellets are good and dry.
2) Generally, the pellets are at room temperature. (How does "quick" heat-up cause condensation? I would think the heat would cause moisture to evaporate!)
3) My stove is actually in the livingroom of my home ... and no, it does not have an OAK installed (regretably!).

My stove is a Regency GFP55.

 

[CJ-SR4ever]

Have you done the good old microwave test? That is a good way to determine the amount of moisture in the pellets.

 

[LRRifleman]

Please excuse my ignorance ... what is the microwave test?

 

[arnash]

Your stove must be different from ones like mine. When they are shut-down, there are no unburned pellets, they burn down to pure ash, sometimes my burn pot is actually empty, with no pellets and even no ash (it falls though the holes I guess). Why doesn't your stove burn all the pellets left in it when shut-down? That doesn't seem right.

 

[twojrts]

The microwave test:

Take a small ceral bowl, put a handfull of pellets in it. Cover it with a saucer. Nuke on high about 1 min. When you take the saucer off, there should be little to no moisture on it. If there is excessive moisture on the saucer, your pellets have too much moisture in them. You can do this when you get a couple of bags to try before buying a ton. In addition to testing a few bags, you should test them for moisture too. Then you won't get stuck with a crappy ton of pellets!

I haven't found the Ligs to have too much moisture. At least not the ones I burned last year.

 

[checkthisout]

Has anyone ever bought a ton of pellets that were thoroughly shrink-wrapped and found they had moisture in them? I suppose it could be the result of inadequate drying before manufacture as well.

 

[SmokeyTheBear]

Let's go back to the basics.

If the stove has a proper venting system, and proper incoming air, when the stove is turned off your combustion fan (and likely your convection fan as well) should go to full speed.

This (provided the stove isn't plugged with ash or the gaskets shot or effectively bypassed) should result in what is in the burn pot being rendered to ash and ejected from the burn pot on top feed stoves.

 

[Don2222]

Hello

Also if you are running the stove on a very low setting like 1 or 2 that contributes to the caked ash. I suggest running it on 3 and use a T-Stat to shut it off when the house gets too hot.