# Lethal carbon monoxide poisoning in wood pellet storerooms



## Sophie

FYI - I heard about this at work:- I don't know if pellets in Europe are made differently than in the US?  This is very serous.  I hope that everyone has working CO detectors.

.http://www.ncbi.nlm.nih.gov/pubmed/22879445.


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## Sophie

More information on this - the storehouses they are talking about are actually residential storage containers.  There is more info at http://www.safteng.net/index.php?option=com_content&view=article&id=2239&Itemid=4:

"Wood pellets for boilers are normally stored in a large sealed hopper/tank or a storage room that has a screw feeder (auger) connected to the boiler. Alternatively, the hopper/tank can be mounted over the boiler for gravity feeding. Due to the enclosed nature of these hoppers/tanks/rooms, the atmosphere inside can become oxygen depleted and a toxic atmosphere containing carbon monoxide can accumulate. The chemical reactions responsible for carbon monoxide production from wood pellets are assumed to be an auto-oxidation process, especially oxidation of the fatty acids to be found in wood4."


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## SmokeyTheBear

Well I guess that goes to show that one should not enter sealed containers connected to a burning device by an auger.  Do a search on here on gummy stove. Same thing writ small.

Or roll in large piles of freshly made pellets inside an unventilated building.


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## rickwai

The only way that I can see this would affect us is if we were to get inside of our hopper on top of our stove. I dont know about anybody else but I usually dont climb into my hopper and hang out...


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## stoveguy2esw

strikes me there have been accidental deaths  from people in grain silo's in the past. probably due to the same conditions


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## smwilliamson

making your own bulk feed storage bin is a bad idea....unless you are an engineer.


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## SmokeyTheBear

Nothing like a big one if you are going to do it however.

http://american-colossus.blogspot.com/2009/05/grand-trunk.html


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## moburns

Im confused.  Do pellet put out carbon monoxide with out being burned?  I have just about two tons scattered all over my home.  Is the CO not an issue because of the amount or because of the place I am storing?  I do have a CO detector.


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## SmokeyTheBear

Maria,

Look at where and how those fatalities occurred.

Do you enter what appears to a normally closed feed hopper connected to a heating device for 60 homes?

Are you down inside a full cargo hold on a ship carrying warm just made pellets?

What is your CO detector reading?


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## moburns

Am I misreading something.  It looked like the casulties happend by people entering pellet storage areas.  I didn't know the people were entering hoppers, thats crazy.

If I tried to climb into my 50lb pellet stove hopper I think I would destroy the stove and maybe the pre-fab chimney housing the pellet liner and I certainly would not be able to close the lid.
My house could possibly fit inside of a cargo liner that ships pellets but at this point it is tied to some cynder blocks in the mobile home park.

I am not sur ewhat the CO detector reading is but it is not alarming me to any issues.


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## SmokeyTheBear

In Europe they have some large systems that provide heat for many buildings and they have automated from storage to burner delivery (large auger systems).

Since it takes a specific concentration for a specific exposure time to cause a problem one should never enter a building that directly feeds fuel (any fuel) via an open pathway (auger) to a large combustion device.

The mere opening of the door can result in combustion byproducts entering the area. It is also an area with little remaining space at times thus the concentration of anything in the air there can be a lot higher than it is outside that area.

The same thing is true of a loaded ship's hold.

I posted a link in a thread yesterday IIRC showing the concentration levels and effects of CO, it even has the "normal" air levels of CO in it. Here is that post: https://www.hearth.com/talk/threads/co-exhaust-gas-compositon.101454/#post-1304097


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## moey

Seems like they could avoid this by just letting them sit in a ventilated area for a couple days. I'd suspect these pellets are being stored still warm.


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## Sophie

The second article said:

"In November 2010 a 38-year-old male householder in Ireland died after entering the 7 tonne wood pellet storage room for his boiler. His wife and another
man were treated in hospital after trying to pull him to safety."

I don't have a bulk storage container but I have read on this site that people have built them in their cellar - I don't know how large they are, and I am not sure why the man who died entered his storage room, but I also don't understand why people people who use wood pellets wouldn't want to completely understand how/why wood pellets emit carbon monoxide. 

Kind of reminds me of smokers were denial decades ago about the effects of cigarettes.  I smoked for 26 years before I was able to give them up but I always realized that putting smoke into your lungs was probably not a very good idea.


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## SmokeyTheBear

Sophie,

If the pellet storage was hooked directly to his boiler then it is the same situation as the setup feeding a heating system for 60 houses.

I am not doubting that pellets off gas when they leave the dryer.  In fact I don't doubt that cord wood off gases as it drys.

I also am a firm believer in having the proper operational detectors in the building which means both CO and Smoke.

I currently have over 10 ton in my garage along with a forced hot water boiler there is a smoke, fire , and CO detector in there interconnected to 4 other siblings.

I once had 18 ton in there no alarms sounded except for the reminder to replace the backup batteries.


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## SmokeyTheBear

Just a bit more information: http://www.hse.gov.uk/safetybulletins/co-wood-pellets.htm


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## Sophie

It appears that pellets bought in bulk are fresher and therefore expel more carbon monoxide than pellets that have been packaged, shipped to a retailer, held for a period of time and then sold by the ton.  I don't know if you have a pellet storage container but it appears that a CO meter would not detect CO in the sealed bulk storage containers but would present a danger when opened - and apparently there is a reason for opening the containers since they are built with access doors. The storage containers are a new concept in the US and consumers should definitely be educated on the CO danger and provided with safety data sheets whether they buy in bulk or in bags.


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## SmokeyTheBear

Sophie said:


> It appears that pellets bought in bulk are fresher and therefore expel more carbon monoxide than pellets that have been packaged, shipped to a retailer, held for a period of time and then sold by the ton. I don't know if you have a pellet storage container but it appears that a CO meter would not detect CO in the sealed bulk storage containers but would present a danger when opened - and apparently there is a reason for opening the containers since they are built with access doors. The storage containers are a new concept in the US and consumers should definitely be educated on the CO danger and provided with safety data sheets whether they buy in bulk or in bags.


 
I do not have a bulk storage (in a confined space with practically no chance of air transfer the usual cause of death for these cases is severe lack of oxygen) silo or space nor am I connected to any auger system dumping pellets into a burner system.

Such systems start out oxygen depleted. So even a very small amount of anything else usually is in high concentration.

Since they haven't provided any actual test results in any of the information I've seen it is quite possible that this was a contributing and even possibly the real issue.

The US CDC has information on some 600+ cases of death in what are classified as confined spaces.

In 42% of the cases it is oxygen deprivation that is the problem, cases of this nature can involve just opening the access area, going inside, and expiring.


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## Sophie

OK - Let's not bury our heads in the sand and recognize that there is a very serious CO problem w/wood pellets and not dismiss this as caused by oxygen depletion in a confined space. 

http://www.pellet.org/images/2010-02-26_Review_of_Off-gassing_from_Wood_Pellets.pdf

Empty confined spaces don't kill people - wood pellets stored in confined spaces kill people.


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## SmokeyTheBear

Sophie said:


> OK - Let's not bury our heads in the sand and recognize that there is a very serious CO problem w/wood pellets and not dismiss this as caused by oxygen depletion in a confined space.
> 
> http://www.pellet.org/images/2010-02-26_Review_of_Off-gassing_from_Wood_Pellets.pdf
> 
> Empty confined spaces don't kill people - wood pellets stored in confined spaces kill people.


 
Actually any thing that fills up a confined space can kill people, this includes other people.


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## SmokeyTheBear

From your PDF Sophie:


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## SteveB

Sophie said:


> Empty confined spaces don't kill people - wood pellets stored in confined spaces kill people.


 
You most certainly can die in an empty confined space. We get training every year at work. Can depend on what was in there before it was emptied and if its sealed it can have an oxygen depleted atmosphere. Just opening a hatchway to get in doesn't necessarily let enough oxygen into a depleted atmosphere unless its ventilated somehow. Sorry, not trying to bust your chops, training comes from OSHA. People die every year.


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## Pellet-King

rubbish!!


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## Dgopetactical

Carbon DIOXIDE is what is put off from composting wood and what is in farm silos. carbon monoxide is a gas that comes from incomplete combustion Of various fuels. Both deadly killers. If you have carbon monoxide in your pellet storage area it's not your pellets.


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## hoverfly

It would  be a good idea to add venting in those storage boxes.


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## TheMightyMoe

Smokey is on target.

If you have a large "sealed" hopper, CO ((FROM THE DEVICE IT IS HOOKED TO)) will gradually fill the hopper up, and leak out into the room the hopper is in. If the room is sealed, CO being a heavy gas will fill the room top to bottom, making it a death trap. Those large pellet hoppers are NOT air tight.

The reason you don't have this kind of problem with a stove, is because the stove/hopper are all contained in one unit, and fresh air is constantly being moved in and out of that room.


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## Sophie

This is a proven and lethal danger. Do you want to wait until someone dies before admitting the truth or are you purveyors of wood pellets?

*Factors affecting the amount of carbon monoxide released from wood pellets*
Wood pellets for boilers are normally stored in a large sealed hopper/tank or a storage room that has a screw feeder (auger) connected to the boiler. Alternatively, the hopper/tank can be mounted over the boiler for gravity feeding. Due to the enclosed nature of these hoppers/tanks/rooms, the atmosphere inside can become oxygen depleted and a toxic atmosphere containing carbon monoxide can accumulate.* The chemical reactions responsible for carbon monoxide production from wood pellets are assumed to be an auto-oxidation process, especially oxidation of the fatty acids to be found in wood4.*
*Experimentation has shown3 that small quantities of wood pellets can produce life-threatening quantities of carbon monoxide in a confined space and that there are various factors that will affect the amount of carbon monoxide produced.*

from this webpage: http://www.safteng.net/index.php?option=com_content&view=article&id=2239&Itemid=4


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## SmokeyTheBear

Sophie,

If you enter a sealed storage facility of any kind you must ventilate it before entering.

Anyone that is foolish enough to enter a portion of an operating heating system (which is exactly what those folk in Europe did) is in extreme danger even if there is no CO. 

They were in essence sucking on an exhaust stream.


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## Sophie

*Experimentation has shown3 that small quantities of wood pellets can produce life-threatening quantities of carbon monoxide in a confined space and that there are various factors that will affect the amount of carbon monoxide produced.*


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## SmokeyTheBear

Let's see placing freshly made pellets into a airtight container at 26  that is 78.8  for 16 days results in CO in a lethal concentration inside that container. 

Yup, nothing to argue with there.

Still need the actual experimental setup and all of the run data.

Concentration is related to the volume of "air" inside that container.


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## Sophie

*http://annhyg.oxfordjournals.org/content/48/4/339.full*

*Conclusions*

High levels of hexanal and carbon monoxide were strongly associated with storage of wood pellets and may constitute an occupational and domestic health hazard. The results from lumber drying show that the emissions of hexanal and carbon monoxide are not limited to wood pellets but are caused by general degradation processes of wood, facilitated by drying at elevated temperature. Emission of carbon monoxide from wood materials at low temperatures (<100°C) has not previously been reported in the literature. We postulate that carbon monoxide is formed due to autoxidative degradation of fats and fatty acids. The depletion of oxygen and simultaneous formation of carbon monoxide may be particularly dangerous in closed spaces.
A toxicological literature survey showed that the available scientific information on hexanal is insufficient to determine the potential risks to health. However, the data presented in this paper seem sufficient to undertake preventive measures to reduce exposure to hexanal both in the industrial environment as well in the domestic setting, where children and sensitive persons may be involuntarily exposed.
_Acknowledgements—_The study was financed by a grant from the Swedish Energy Agency and by Västernorrland County Council, Sweden. The authors would like to thank Christer Edling, Tony Waldron and Kåre Eriksson for valuable comments.

Smokey - Thank you for arguing this issue - it made me educate myself and look more closely at the dangers of wood pellet storage in my home. I hope that everyone who uses wood pellets will read the links, research the issue and demand appropriate legislation to  educate consumers and ensure the safe use of wood pellets.


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## TheMightyMoe

http://annhyg.oxfordjournals.org/content/56/7/755.full This is the journal you are referencing.

Read the full article and come to your own conclusion. I will agree that it is possible that CO produced from pellets alone, could have caused these deaths, but is highly unlikely.

In the case of the German in the 144 ton silo or the people in ships hulls with 10,000 tons, yes I could see CO being a problem.

They said that combustion from the boiler is ruled out, but they did not say how they ruled it out. Just because it was installed to code/safety regulations, does not mean it does not leak CO over time, and they did not mention how they tested for this.

*Reference 3:*
However, their testing for the pellets, seems highly bias, they did not include multiple container size, none of the containers were ventilated at ANY level, etc... If you put A LOT of ANYTHING that decays in a small container, the gas PPM is going to be extremely high, if you double the size of the container, the PPM would be halved. They did not include any ratios, to back up their data values. They also did not vent the containers, and re-test them, to see the continued CO output of the pellets, which would have been EASY to do.

Many of these firms/schools are payed to get results, skewing the truth, is money in their pocket. Now that they found this problem, they will make a lot of money looking into it. There is a BIG difference in results, based on the testers.

HOWEVER,

Any sealed basement/lower level room, should have a CO detector... Because if the boiler/furnace is leaking CO, that is where it is going first...

Edit** Looks like replies were made since I typed this.


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## SmokeyTheBear

No matter what fuel you use or how well maintained your heating system is it is always possible to have a CO issue.   You don't even have to store anything anywhere under any condition.

It is possible to suck enough inside your building from operating engines improperly placed outside your house or even properly placed outside your hose if conditions are right.

Always, always, have a working set of working  (CO/Smoke/Fire) detectors, they save lives.  Never disconnect them or remove the batteries, always replace them with fresh ones at least once a year.

TheMightyMoe,

I suspect they may not have had a method of ruling out stuff from the boiler.  

If one searches on here you can come across smoke in the hopper threads. 

A sealed hopper system can actually draw combustion byproducts from the firebox into the hopper. 

In fact,  I can cause that to happen anytime I choose by allowing the burn in my stove to degrade to the point that the fire isn't completely out when the combustion blower stops, open the hopper (mine is a non sealed system) and apply a vacuum cleaner above the pellets.

The partial vacuum in a sealed hopper (or silo, or bin with an auger system)  can cause this as well (see reference to Gummy Stove in this thread).

The mention of partial vacuum should make people look at yet another reason to check for negative air pressure in their home. 

I won't even mention what comes next but it has probably been beat to death many times each season on here.


Sophie,

Happy the argument has lead to further research.


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## khenault

SmokeyTheBear said:


> Nothing like a big one if you are going to do it however.
> 
> http://american-colossus.blogspot.com/2009/05/grand-trunk.html


 
That's almost big enough to hold your stash.


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## Hansson

Over here it's recommended to have ventilation in the bulk storage.
Heres a artikel I found
http://translate.google.se/translate?sl=sv&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&eotf=1&u=http://www.brandsakert.se/2011/0606/pellets-kan-d%C3%B6da


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## Tim Linden

The majority of us will have pallets of bags of pellets, not just huge piles of raw pellets. I would think
each bag individually sealed would prevent massive amounts of carbon monoxide from being
released into the room they are stored in. So I don't think they are talking about the same "bulk storage"
as you are thinking..  I still agree that having detectors in all homes is a must, but I'm not going to return
my pellets in fear..


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## Hansson

No danger whit pellets bags what I have heard of.
Sorry maybe I was off topic


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## Sophie

For those of you in denial, these are just a few of the reasons why consumers need to learn about the very lethal CO problem caused by wood pellet residential bulk storage:




http://www.mywoodpelletsolution.com/wood-pellet-storage/
http://www.acornenergycoop.com/index.php/offerings/wood-pellets
http://www.maineenergysystems.com/Pellestore_3TX.htm
http://www.pellergy.com/bulk-wood-pellet-delivery/
http://fehls.com/pages.aspx?id=28

I am not saying to give up heating with wood pellets - I am saying that* consumers need to be educated regarding this very serious issue before fatalities occur due to lack of knowledge.*

Hansson - you were not off topic - your comments were exactly the subject of this post.


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## Tim Linden

Hansson I was more referring to Sophie. The distinction has to be made that it's
bulk pellets as in a huge pile of pellets not bulk pellets as in a pallet of individually
wrapped bags. Those videos are great so anyone who doesn't understand the
difference can see if they are filling up a massive hopper in their garage or not..


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## smwilliamson

There has been work as of late to develop a standard for bulk delivery and storage of wood pellets lead by the BTEC (bio thermal energy council). Part of the recommendations is for proper ventilation of all storage containers. There is also recommendations for possible dangers for delivery into homeowner constructed containers. I'll post a link to the white papers.


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## DneprDave

TheMightyMoe said:


> In the case of the German in the 144 ton silo or the people in ships hulls with 10,000 tons, yes I could see CO being a problem.


 
CO build up would not be a problem in ship's cargo holds as they are ventilated with very large supply and exhaust fans. I know because I'm one of the guys who fixes them!

Dave


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## Sophie

DneprDave said:


> CO build up would not be a problem in ship's cargo holds as they are ventilated with very large supply and exhaust fans. I know because I'm one of the guys who fixes them!
> 
> Dave


 
The Oxford Journals doesn't agree with you:  http://annhyg.oxfordjournals.org/content/52/4/259.short?rss=1

This site republished the article and there is additional information about CO produced by other organic products:  http://community.fireengineering.com/forum/topic/show?groupUrl=copoisoning&id=1219672:Topic:67906


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## DneprDave

I gotta say I really don't see how CO *could* accumulate on the ships I sail on. There is way too much air flowing through the holds. Air is circulated to move heated air caused by the refrigerated containers out of the holds and replace it with cool outside air. The volume of air in the cargo holds is completely changed many times an hour.

Even with the bulk carriers I've been on, where the air isn't changed out, the holds are sealed, no gases could get out under any circumstances and they are tested for oxygen and toxic gasses and ventilated each time anyone has to enter a cargo hold. 

I guess that what they say about foreign ships being less safe than U.S. ships is true.

Dave


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## smwilliamson

As with most things, there is a bit of trial and error which leads to policy and regulation. Simple answer on bulk storage...silo outside of the home. As boilers gain more traction and bulk delivery becomes more common I'm sure there will be reported instances of death and hospitalization as more and more weekend warriors construct plywood bulk bins in their basements.


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## libirm

http://biomassmagazine.com/blog/article/2013/02/wood-pellets-and-storage-safety


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## PassionForFire&Water

Fresh delivered wood pellets in bulk do offgas CO.
If these bins are not properly desinged they can be deadly

Bulk wood pellet storage bins should be sealed with a ventilation to the outside.

There is a working group here in the Northeast that is working a guidelines for wood pellets storage systems

http://biomassmagazine.com/articles/8602/wood-pellets-and-storage-safety

Some examples below


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## PassionForFire&Water

For those of you that want to learn more on this topic: *CO off-gassing from the bulk storage of wood pellets*

Tuesday, February 19th at 10AM ET.

This session will be held via webinar, and you may register here: https://www2.gotomeeting.com/register/232015474


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## heaterman

It has to be said that ANY biological material, be it cordwood, straw, grass, pellets or whatever, creates hazardous gases. The issue is not the fuel itself but rather ventilation of the storage area. This is not a huge issue, just something that needs to be addressed when considering bulk storage.


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## Swaybar

Dgopetactical said:


> Carbon DIOXIDE is what is put off from composting wood and what is in farm silos. carbon monoxide is a gas that comes from incomplete combustion Of various fuels. Both deadly killers. If you have carbon monoxide in your pellet storage area it's not your pellets.


 

Carbon monoxide ( CO ) is produced from the partial oxidation of carbon containing compounds; it forms when there is not enough oxygen to produce carbon dioxide ( CO2 )


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## nailed_nailer

Here is everything you ever wanted to read about entering "Confined Spaces"
A Big OSHA no-no if not done correctly.

https://www.osha.gov/SLTC/confinedspaces/

Whats inside the confined space doesn't really matter.
Its the safety controls for that space that does.

Ask any welder that works in an industrial field about working on/in tanks.

---Nailer---


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## fireguy976

Couple misconceptions here,

CO has a density of 0.97 that of air. Therefore, it being almost exactly the same, it Does NOT rise to the top, nor sink to the ground. It mixes readily with air. That's why any CO alarm can be either plugged into a low wall outlet, or if it is a combo CO and smoke alarm, it can be placed on the ceiling. And the correct name for these is alarms, NOT detectors. Detectors are only found in the complex fire alarm systems with the pull stations, bells, or horns, flow switches etc, but most people get the nomenclature wrong.
Here is the big reason why CO is the BAD BOY. It's a true poison, every time you take a breathe in an environment with CO, the CO molecule binds with the red blood cell and doesn't want to let go. Now that blood cell cannot carry any oxygen around. Pretty much useless. The CO is sticky to the blood cell, and hard to get rid of. So every new breathe brings in more CO, and binds to more blood cells and accumulates like murcury in a fish. After several hours in a low level CO environment you start to feel weak, nauseous, sick, and the eventually pass out and die. That's why even low level exposure but over a several day time frame can be deadly.
Sorry for getting technical, but for those who want to know the scoop, that's it. I teach this stuff 

So if someone is bulk storing new, or raw pellets in their home, (as some have stated, bagged stuff is usually no longer raw or really fresh) they really need to look into proper ventilation to the outside. Bulk bins or mini silos in a garage should not be a concern. First off, attached garages are supposed to be gas (vapour not the liquid) proofed, that's why you can store your cars etc in there. Also garages are almost never as air tight as homes, so any off gassing of fresh pellets would not result in a CO build up in a garage.

As I go through about 5 tons a winter, I'm getting tired of slinging bags around. Several local pellet mills deliver either bagged or bulk. I'm now looking into bulk storage solutions. 

I'll use the sign off from hickok45, so as I've given him credit I'm sure he won't mind,

"Life is Good"

Cheers,
KJ


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## smirnov3

I have had a CO monitor in the same room as my pellet stove (up above it - since CO is lighter than O2) and is has never gone off.


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## stoveguy2esw

smirnov3 said:


> I have had a CO monitor in the same room as my pellet stove (up above it - since CO is lighter than O2) and is has never gone off.


 

CO has roughly the same atomic weight as nitrogen which make up the largest part of our atmosphere. IMHO CO detectors should be placed about "head high" as mixing of gasses will happen readily and with the similar atomic weight as well as the fact that CO from a woodstove is heated would result in concentrations being higher in the room


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## Fsappo

TheMightyMoe said:


> Smokey is on target.
> 
> If you have a large "sealed" hopper, CO ((FROM THE DEVICE IT IS HOOKED TO)) will gradually fill the hopper up, and leak out into the room the hopper is in. If the room is sealed, CO being a heavy gas will fill the room top to bottom, making it a death trap. Those large pellet hoppers are NOT air tight.
> 
> The reason you don't have this kind of problem with a stove, is because the stove/hopper are all contained in one unit, and fresh air is constantly being moved in and out of that room.



Funny, I just noticed a blurb about proper storage of "bulk" pellets while researching NYSERDAs newest pellet stove upgrade program.  I was wondering what may have triggered that.  I haven't seen it as much of an issue here in Central NY.   Not a lot of folks (only one I met in 7 years up here) use bulk pellets.


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## SidecarFlip

I need a tinfoil hat and some buttered popcorn....


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## heaterman

SidecarFlip said:


> I need a tinfoil hat and some buttered popcorn....


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## adam6979

smwilliamson said:


> making your own bulk feed storage bin is a bad idea....unless you are an engineer.


Please enlighten me more.... I am considering building a 4x4x12 storage bin to hold bulk pellets.... However I am making it semisealed - seems caulked with a lid - pretty much air tight to prevent the dust from when they fill it from blowing all over the shop.... Don't want to be making a mistake trying to make less work for myself.


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## velvetfoot

I'll chime in even though I don't know anything.  Maybe others that actually have storage will add something.
I would think there'd have to be an exhaust hole of some sort because they're blowing the pellets in-the air has to go somewhere.  If that exhaust doesn't go to the outside, then it'd have to be filtered, and I'm not sure much good would come of that.
I imagine that if there are fill/exhaust ports on the outside of the building, they could serve to ventilate the bin for a certain period of time until the off gassing is done, but I don't know for sure.
Is this bin horizontal or vertical?  I can see more of a problem filling a low horizontal bin.


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## adam6979

I think you are right... never thought about that, will have to investigate more. Certainly don't want to blow compressed air into an air tight box. Caulking is tough too... boom comes to mind! Mine would be 4 foot squared and 12 foot high. Indoor vent with a filter would have to be if needed because external vent could allow moisture to be introduced in the box -- with catastrophic results. I wont be building till later this summer but will certainly research fully. I can totally see though how if you had a bulk feeder going into a burning appliance CO2 could back up in the box. Mine will just be freestanding though... not sure it is much of a concern at all. And I certainly would not be getting into it at all. Probably just reaching through the trap door on the side once in a while to vac out all the sawdust.


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## bdud

I have a metal bulk storage bin, ~3.2 - 3.4 tons, with a pellet boiler in my basement. I have one CO / smoke detector almost  above the boiler and about 10 foot from the silo. I also have another CO / smoke detector in a basement bedroom and another CO detector at the top of the stairs leading to the basement. None of these detectors has ever gone off, not even during the bulk filling of the silo, though I do have the bulkhead door open.  I can't believe all 3 are faulty, they are all different models. 
At the top of the silo is a cloth filter "sock" so the silo is vented into the basement. I would say the smell is less than when I was storing 3 tons of pellets in my basement in bags.
First time I had my metal silo bulk filled I had a dust issue in my basement. I had designed my silo to fit in an area where my oil tank was and it was a tight fit to get the max in that area without it looking stupid. Because of plumbing, walls, etc there was one section I could not bolt together fully. I sealed everything as I was putting it together with duct sealer but the pressure of the delivery truck opened that seam up. When the silo emptied I repaired it with rivnuts and angled steel from the inside and sealed it all up. 
The next delivery I had no leakage, though the cloth filter "sock" does tend to get very full of dust. I do have a vent pipe on my silo same size as fill pipe, that is also capped outside which is opened during delivery. I use a pipe from the delivery driver and the last couple of times I use the vacuum / bagger attachment from a leaf blower loosely connected to the vent hose. Trying to get a bit of negative pressure in the silo, not sure what pressure the delivery truck uses. At the very end, just before the delivery truck stops the delivery, automatically stops?, I get maybe a handful or less of pellets out the vent pipe. 
I clean the cloth filter "sock" after the filling and the level of the pellets is just below the top of the silo, very happy with that.
You certainly need a vent to the outside when filling a solid storage bin. I believe the cloth silos filter and capture the dust but they get progressively harder to fill as the pellets fill, unless they have an external vent pipe during filling. 
I don't think you would need an external vent after the silo has been filled, but an internal vent to allow any build up of gases to disperse would be desirable. My volume of pellets and most house owners is a lot lower than the industrial / whole room silo's, where special precautions need to be made.


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## velvetfoot

bdud said:


> I do have a vent pipe on my silo same size as fill pipe, that is also capped outside which is opened during delivery.


Why would you need an internal vent with the sock if it's vented to the outside?


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## bdud

velvetfoot said:


> Why would you need an internal vent with the sock if it's vented to the outside?


The outside vent is only open when filling to relieve pressure. You would need a vent also during normal operations, pellet level going down, left off gases on a continual basis. You could use a vent outside but you would need to ensure it is above the snow line, could look ugly (tall pipe on side of house) and might introduce moisture into the pellets. 
I just kept with the recommended method.


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## bagpiper8

stoveguy2esw said:


> strikes me there have been accidental deaths  from people in grain silo's in the past. probably due to the same conditions



Had a couple of those out here in Colorado in the past years. Grain silos can be terrible places for organic toxins as well as just mold. We had a guy perish in a sugar tower years ago as well. Stay clear of wherever grains and such are stored unless you have a strong vent/fan going.


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## GeHmTS

moburns said:


> Im confused.  Do pellet put out carbon monoxide with out being burned?  I have just about two tons scattered all over my home.  Is the CO not an issue because of the amount or because of the place I am storing?  I do have a CO detector.




Let's be clear, you can only cause CO from pellets through combustion.


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## ChrisWNY

Interesting discussion. Wanted to add this article to the debate, which claims that off-gassing from storage of residential wood pellets is essentially a nonissue...

http://biomassmagazine.com/articles/12297/study-suggets-residential-pellet-offgassing-a-nonissue

As others have already noted in this thread, confined spaces with no or poor ventilation in and of themselves are problematic for a number of reasons.



GeHmTS said:


> Let's be clear, you can only cause CO from pellets through combustion.



Not entirely true. Due to natural processes of enzymatic breakdown of wood pellets (especially freshly-cut wood pellets), *some* CO can be off-gassed as a byproduct, without actually combusting those wood pellets in a fire. However, recent studies that I've read have indicated that the off-gassing is so insignificant that wood pellet storage (whether inside a silo or basement) should not present any health hazards.


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## Deezl Smoke

smwilliamson said:


> making your own bulk feed storage bin is a bad idea....unless you are an engineer.



 I'm pretty sure the facilities that the fatalities occurred were designed by degree holding engineers.


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## bostonfan49

....in the for what it's worth dept. Here are pics of my 2 bulk fill pellets bags. Combined total of the 2 is a smigon under 3 tons. It's hard to see, but on the top of each bag are two circular vent flaps atttached to 2 dryer hose. As each bag is bulk fed from the truck, the two hoses go out my basement window, completing the venting process. The bags do "breathe" but you still have to have an escape venting route for the exhaust/dust! The bags are empty now. Vermont Renewable Fuels comes this coming Monday morning to drop off just shy of 3 tons of Green Mountain Pellets ( Softwood)
Bill


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## Letsburnwoodnotoil

Dgopetactical said:


> Carbon DIOXIDE is what is put off from composting wood and what is in farm silos. carbon monoxide is a gas that comes from incomplete combustion Of various fuels. Both deadly killers. If you have carbon monoxide in your pellet storage area it's not your pellets.


Not true. There is CO produced when pellets off-gas.


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## Letsburnwoodnotoil

GeHmTS said:


> Let's be clear, you can only cause CO from pellets through combustion.


Absolutely not true! Be careful.


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## heaterman

GeHmTS said:


> Let's be clear, you can only cause CO from pellets through combustion.



Not true. Any organic matter will release CO as a byproduct of decomposition. Combustion just accelerates the process.
A silo on a farm is a good example. No combustion going on in there but it is a relatively sealed space and the slow "oxidation" or decay process of the organic matter will release CO and other gases.
I lost a high school classmate and good friend a few years back in a silo filled with corn. He went in without ventilating it and was dead in two minutes. 
The silo had been sealed up since filling the previous year. Left a wife and 3 kids behind at 42 years old. 

Can CO happen? Yes it can. 
Is it enough of a threat to my life to avoid putting a pellet storage bin in my basement? No.
Just be aware of what you are dealing with.


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## johneh

The hoppers they are talking bout are large sealed units
 for the storage of large amounts of pellets. Industrial setting. 
Companies that make pellets. Large users like power plants 
Not the guy that has 2-3 ton in his home


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## DeadTreeBurner

johneh said:


> The hoppers they are talking bout are large sealed units
> for the storage of large amounts of pellets. Industrial setting.
> Companies that make pellets. Large users like power plants
> Not the guy that has 2-3 ton in his home


This seems to be correct. I have a basement with a partial crawlspace that is conditioned. I have 4.5 tons of bagged pellets stacked in there and had a CO monitor with the pellets and never had any CO levels detected in the multiple times I checked it. The space did have a strong odor from the pellets though.


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## faultymechanics

Just ot add to this, I have a MESys Boiler and 5 ton fabric hopper in my basement. The system is fed with an Auger and Vacuum system as well as bulk fuel delivery. There's a lot that goes into the fill process (inflating hopper, grounding the system etc), however, I've never had a CO issue. I'd also imagine my basement/ crawlspace have more than enough air circulation to reduce any off gassing....if there is any. We've had it in our basement for about 9 months now.


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## SidecarFlip

Never been an issue with me as I keep my fuel in the barn and mix it (corn/pellets) in 4 30 gallon trash cans that go on the back deck via my forklift.  Comes in a bucket at a time and yes, pellets have an odor about them.  Not unpleasant.


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## augiedoggy

So if I understand this correctly, if one is making a larger hopper for pellets, they would want to include a vent. This would allow the stove to displace the space that was occupied by the pellets being dumped with atmoshere air instead of forcing co2 exhaust gas to be "pulled" more or less into a sealed hopper through the same hole the feeding the combustion chamber? Either way, depending on stove an exhaust design and pressure inside the stoves combustion chamber, there may be higher levels of c02 inside a typical hopper while a stove is running.

 (yes pellets can produce their own co2 but that would be negligible in this application given the amount and the time period they are spending in the hopper, correct?)


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## johneh

Wood pellets off-gas CO2 
So hoppers need to be vented not 
sealed to the outside air. In order 
to get enough CO2 from pellets you 
would need a grain elevator full and 
*SEALED* . This is most unlikely to happen
 in your house with wood pellets alone


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## augiedoggy

johneh said:


> Wood pellets off-gas CO2
> So hoppers need to be vented not
> sealed to the outside air. In order
> to get enough CO2 from pellets you
> would need a grain elevator full and
> *SEALED* . This is most unlikely to happen
> in your house with wood pellets alone


Yes, Thats my understanding of it too but the home stove hopper would need to be vented still, not because of risk of co2 buildup from the day or two the pellets reside in the hopper between fills but rather the co2 that would be pulled in from the negative pressure of the pellets dropping and to offset the space with makeup air instead of gas from the combustion chamber.


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## johneh

If the hopper were totally sealed it would also be under neg pressure so CO2 would also be pulled into the combustion chamber. If the hopper is not sealed it is still under negative pressure because the pellets are being dropped or pushed into a negative pressure stove and the hopper is not sealed from the combustion chamber 
I have also never seen a totally sealed hopper even with a gasket all around the top lip


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## DeadTreeBurner

augiedoggy said:


> Yes, Thats my understanding of it too but the home stove hopper would need to be vented still, not because of risk of co2 buildup from the day or two the pellets reside in the hopper between fills but rather the co2 that would be pulled in from the negative pressure of the pellets dropping and to offset the space with makeup air instead of gas from the combustion chamber.


What size hopper are we talking about? If it's on the stove, it ain't producing anything close to what would suffocate/kill a person.


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## shootrj2003

Entering any tank or storage container has potential air problems. They have training for that in the Navy ,fire departments,etc. I’m surprised that I survived my teenage years after doing things me and friends did.!


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## Homeskillet359

stoveguy2esw said:


> strikes me there have been accidental deaths  from people in grain silo's in the past. probably due to the same conditions


That's different, thats more of a suffocation where they sink into the grain and can't get out.


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