Moisture absorption into pellets from humidity

[Doug Doty]

I found this video:

http://www.pelheat.com/Keep_Wood_Pellets_Dry.html

Being in the plastic industry, we have to pull almost all the moisture out of hydroscopic materials " wood pellets are very hydroscopic " in order to process and turn plastic pellets into parts. Once dried, the pellets or resulting part is a moisture magnet and will seek a moisture equilibrium over time, this happens very slowly in very low humidity and very quickly in very high humidity. Having bought an indoor / outdoor thermometer with humidity too, I have started taking note of the obvious in humidity swings out doors vs indoors. It sure would seem that unprotected pellets exposed to outdoor humidity would degrade over time and it would be a real spike in the rate of moisture absorption every time a shower come through the area and the humidity goes up to 99% for a day or so. My unheated attached garage seem to run consistently at 55%, even during these times so that is my new store house. I have seen pellets of the same brand that were kind of ok at the beginning of this season this year and are just horrible now. I guess what I am thinking is they all started out equal within a brand or lot because of processing but who knows this time of year depending on where and how they were stored. Under roof could be a lot different than indoors. I also wonder if some brands are actually sealed bags and protected. I know for a fact my Easy Heats were in bags that are heavily perforated on the ends, I am assuming this is to let air out for stacking but I really don't know. Are other brands sealed ??

What do the experts have to say about pellet storage over time.

 

[kappel15]

I have pellets from 3 to 4 years ago stored in my unheated shop. They are doing fine. But I'm no expert on the subject. lol kap

 

[TimfromMA]

I've had pellets around up to 2 years and no problems.

 

[LordmetalZ28]

Ive got pellets from 2013 no moisture damage. I imagine these pellets sit outside in a yard over the summers so ive come to the conclusion my basement that gets very humid only between spring and summer and on the other end between summer and winter when the central air or gas heat isnt on. Although I run a dehumidifer I can only run it may thru october as the low basement temperatures will freeze the coil. So it may sit in 70% for 4 months or so. Well find out

 

[bags]

No expert here but I did notice that pellets stored under roof outside can be moisture magnets. I have mine out on the side of the barn that has a roof sticking out covering all and a cold concrete floor, but open on three sides. Typical lean too side to keep stuff out of the rain. Doug, Where you and I live in the Ohio River Valley we are prone to humidity and you know this well being a boater. What about that early morning fog? Intense sometimes, huh?

That said and my experience I saw something somewhat concerning one morning. It was after it had been cold awhile and then warmed up the following day. The cold pellets in the bags attracted tons of air moisture. The Somersets are in pretty tight bags and do not have any large perforations but like most pellet bags they still have them and I also think it is for ease of palletizing but also to let them breath.

This was only happening on my opened skid though. The unopened covered pallets did have it on the outside but the moisture was not able to get onto the bags inside the covering. I still have them out there and have not experienced any problems at all and the moisture has continued but I use them before they get to soak any up also. That said I have begun to cover the opened skid up much better with a small tarp even though rain will never get to them. I could see after prolonged storage periods this could become a problem.

Whatever pellets I have left for storage over the summer and such will be protected by extra measures because I (and you) live in a very moisture prone valley. I would also venture to say some pellet bags will let more moist air infiltrate.

Oh yeah, buddy. I was telling you about the Somersets a while ago too...... LOL! I am a newbie, but I do know good stuff when i see it and use it. I am working on something in this regard for a better purchase option too. Not sure how far you went but they are sold all around me and it's not that far. If you got them in Batesville then that is obviously closer. Keep any and all of your pellets dry. Stay Warm! We'll be having a heat wave tomorrow. Time for a ride!

 

[Doug Doty]

I bet from all the reading I have done that your harmon stove will process pellets that give my cheapie stove fits. I think this rectangular non agitated burn pot is not nearly as good as agitated or any form of pushing ash out like your Harmon...

 

[kappel15]

I do unload mine by hand and restack on a pallet with the cardboard on it. When it is full, I put the plastic back over the stack. This probably adds to keeping them dry. kap

 

[TimfromMA]

I'm fortunate enough to have enough room in my house to store all my pellets.

 

[bags]

I bet from all the reading I have done at least that your harmon stove will process pellets that give my cheapie stove fits. I think this rectangular non agitated burn pot is not nearly as good as agitated or any form of pushing ash out like your Harmon...

I don't use the agitator on the 45 and the 68 doesn't have one. However, both pots are open on the front side where ashes are pushed out and over into the ash pan below.

Kap, I am planning on the same storage. Once inside the barn or shop here for longer term storage the outside moisture will stick onto the sides of the buildings and not on the pellet bags inside. I am in an open air under roof set up currently and it works fine too but the bags do attract moisture.

 

[velvetfoot]

I new to this, but I wonder how any leftover pellets, or those purchased in an early buy for that matter, will last in the basement over the summer. It does get damp down there, like all basements. I have a heat pump water heater, but I'm resistant to running a dehumidifier. Maybe when it gets really humid...

 

[bags]

Doug,
I am paying close attention to the different designs of how the burn pots are set up and some make way better sense to me than others. I have seen some where the theory is that the ash will fly out and fall thru the holes. Not realistic IMO. Even the Harmans need some quick help from time to time. Ash likes to cling to the sides of the pot and together. This is quickly remedied with the 10 second once a day pot scrape while the stove is running. I do it every time I toss another bag in whether it needs it or not. Usually does but I could not do it and have for days to see if the tank would continue to roll. I will without a hitch but the flame does become lazier and less effective in due time.

I can see problems with the "ash flies out on it's own and drops thru" designs because I see how well this helium inflated and heavier falling thru ash simply will not do what some designers feel it should do. This ideal design is flawed because in the real world that is not how the ash responds. Same holds true with better designs. Eventually they too become jammed up, clogged, and unable to remove enough ash build up to operate. Hence the burn pot scrapes and cleaning regiments.

Throw in some bad pellets and this issue goes from a slow leak at the valve stem to a blow out rapidly bringing any stove to a screeching and thumping halt.

 

[bogieb]

I new to this, but I wonder how any leftover pellets, or those purchased in an early buy for that matter, will last in the basement over the summer. It does get damp down there, like all basements. I have a heat pump water heater, but I'm resistant to running a dehumidifier. Maybe when it gets really humid...

I had 20-30 bags of Curran's left over from last year and kept them on a pallet in the unfinished, mostly un-insulated basement. I live 3 blocks from the river and the lot next to me - 20 feet from house is literally a swamp and there is always running water to the culvert between the two properties - so it gets fairly humid. I do not run a humidifier. The pellets I stored looked and burned just fine this fall.

Now the current batch of Currans (bought this fall), are really nasty and I am wondering if they were left outside in all the rain we had last summer because I can't think of anything else that would create such a change (and yes, I've run other kinds this winter that do just fine, so it is the pellets)

 

[moey]

It only makes sense if you keep them at a high humidity they will eventually assimilate.

I regularly burn pellets that are 3+ year old never noticed a difference, but the area they are in does not see high humidity levels.

 

[Peterfield]

Great thread. I have speculate in other posts about pellet users that have 10-20 tons and are they going to have issues next year. Seems to not be a problem which is good. Thinking about getting a shed or lean-to of some sort to free up garage space but was hesitant to bulk store and risk losing pellets over the summer.

 

[SmokeyTheBear]

Why speculate some of us will spill the beans.

 

[sportbikerider78]

Every situation is different.

I stack mine in my basement with a dehumidifier going all year round. It keeps the air at 55% RH. I did put them right on the floor and I will not make that mistake next year.

The only way to really figure it out would be to weigh a bag start of season and end of season. Same bag.

 

[mepellet]

I have pellets from 2011 that are still doing fine. Stored in my basement since the day I bought them. (September 2011).

 

[mepellet]

I had 20-30 bags of Curran's left over from last year and kept them on a pallet in the unfinished, mostly un-insulated basement. I live 3 blocks from the river and the lot next to me - 20 feet from house is literally a swamp and there is always running water to the culvert between the two properties - so it gets fairly humid. I do not run a humidifier. The pellets I stored looked and burned just fine this fall.

Now the current batch of Currans (bought this fall), are really nasty and I am wondering if they were left outside in all the rain we had last summer because I can't think of anything else that would create such a change (and yes, I've run other kinds this winter that do just fine, so it is the pellets)

I don't run a humidifier in my basement either.

 

[Doug Doty]

I am nuts over wanting to know things and not wonder. I will take an average weight of the next 4 bags of Somersets just for curiocity and then tag one for a long term keeper outside but sheltered and see if it gets heavier over time. My refrigeration scales will weigh them full in the bag to within a 1/4 ounce. Give me some time.

For what it is worth, my current somersets that do so well got rained on somewhere along the way cause I knocked ice off the top of the pallets when I put them in my pole barn. At least the test bags I bought ran well, they came from a broken pallet they were selling bags off of in the same whse. as the 2 ton I just bought.

 

[pageyjim]

I found this video:

http://www.pelheat.com/Keep_Wood_Pellets_Dry.html

Being in the plastic industry, we have to pull almost all the moisture out of hydroscopic materials " wood pellets are very hydroscopic " in order to process and turn plastic pellets into parts. Once dried, the pellets or resulting part is a moisture magnet and will seek a moisture equilibrium over time, this happens very slowly in very low humidity and very quickly in very high humidity. Having bought an indoor / outdoor thermometer with humidity too, I have started taking note of the obvious in humidity swings out doors vs indoors. It sure would seem that unprotected pellets exposed to outdoor humidity would degrade over time and it would be a real spike in the rate of moisture absorption every time a shower come through the area and the humidity goes up to 99% for a day or so. My unheated attached garage seem to run consistently at 55%, even during these times so that is my new store house. I have seen pellets of the same brand that were kind of ok at the beginning of this season this year and are just horrible now. I guess what I am thinking is they all started out equal within a brand or lot because of processing but who knows this time of year depending on where and how they were stored. Under roof could be a lot different than indoors. I also wonder if some brands are actually sealed bags and protected. I know for a fact my Easy Heats were in bags that are heavily perforated on the ends, I am assuming this is to let air out for stacking but I really don't know. Are other brands sealed ??

What do the experts have to say about pellet storage over time.

Great question I have wondered this myself. One thing to keep in mind is relative humidity is relative. For instance where I live today it is 39 degrees with 40% relative humidity outside. Inside I have a temp of 68 degrees and 37% relative humidity. One might think it would be better to store pellets inside where there is less humidity. But relative humidity being relative there is less moisture in the air outside. Warmer air can hold more moisture. I have a humidifier inside. There is more moisture in the air inside even though there is less humidity.

Psychrometric chart.
(broken link removed)

 

[railfanron]

As long as the pellets are inside a dry place I doubt there will be any damage. I burned some of last year's pellet the other day and they burned just as good as this years. Ten years ago TSC was closing out some smoking pellets (used to smoke meat) for 3.00 a bag. I bought ten bags for smoking and they've all worked fine. I still have 2 bags left that I know will work fine next spring. They're stored in the loft of my workshop.
Ron

 

[mepellet]

Great question I have wondered this myself. One thing to keep in mind is relative humidity is relative. For instance where I live today it is 39 degrees with 40% relative humidity outside. Inside I have a temp of 68 degrees and 37% relative humidity. One might think it would be better to store pellets inside where there is less humidity. But relative humidity being relative there is less moisture in the air outside. Warmer air can hold more moisture. I have a humidifier inside. There is more moisture in the air inside even though there is less humidity.

Psychrometric chart.
(broken link removed)

Ahhh the good ol' psych chart. Been a couple years since I have used one of those!

 

[rona]

I found this video:

http://www.pelheat.com/Keep_Wood_Pellets_Dry.html

Being in the plastic industry, we have to pull almost all the moisture out of hydroscopic materials " wood pellets are very hydroscopic " in order to process and turn plastic pellets into parts. Once dried, the pellets or resulting part is a moisture magnet and will seek a moisture equilibrium over time, this happens very slowly in very low humidity and very quickly in very high humidity. Having bought an indoor / outdoor thermometer with humidity too, I have started taking note of the obvious in humidity swings out doors vs indoors. It sure would seem that unprotected pellets exposed to outdoor humidity would degrade over time and it would be a real spike in the rate of moisture absorption every time a shower come through the area and the humidity goes up to 99% for a day or so. My unheated attached garage seem to run consistently at 55%, even during these times so that is my new store house. I have seen pellets of the same brand that were kind of ok at the beginning of this season this year and are just horrible now. I guess what I am thinking is they all started out equal within a brand or lot because of processing but who knows this time of year depending on where and how they were stored. Under roof could be a lot different than indoors. I also wonder if some brands are actually sealed bags and protected. I know for a fact my Easy Heats were in bags that are heavily perforated on the ends, I am assuming this is to let air out for stacking but I really don't know. Are other brands sealed ??

What do the experts have to say about pellet storage over time.

I have 3 ton of Indeck 5 years old stacked on pallets in our car garage. The cement will sweat like in the spring but the pellets are fine. Menards had a very good sale when they had their grand opening and I filled the garage. It was a lucky deal because corn went up at the same time so I had plenty of fuel at a cheap price.

 

[Dr.Faustus]

I keep a major supply of pellets in my unheated garage. i've maxed out at 18 tons a few times. i use the oldest first, and at the end of every heating season replenish what i used. I am often 4-6 years ahead of the game, so in any given winter, the pellets im burning are at least 4 yrs old if not older. Never had a problem even in the super humid NY summers. I have lost 2 bags to moisture since 2008 but that was because i parked my snowy car in there and the water got to the bags on the floor. Now i use pallets to start stacking and havent lost a bag since.

I tend to bring in 10 bags every weekend, which is enough to last me until the next weekend where i bring in more. i store these in the stove room, and i do have a feeling they tend to dry out even more once in the heated the heated stove room.

my pellet bags also have vent holes in them, and always have, except the ones i bought this fall, they are sealed for some reason. It seems like they were vacuum packed honestly. I see no difference in the pellets, however i do like the bags not having any perfs, because it is way easier to repurpose a bag that has no holes in it. BTW the ones with no holes are green supremes, a brand which i've read has had a few complaints on here, is typically regarded as a shoulder pellet- however having burned many different type of brands my stove does not seem to care what i feed it and have been heating my house with the green supremes for the past 3 years.