Value Added Wood Processing

You are not logged in. [ Login ] Why log in
(NOTE: Login is not required to post)

Burning sawdust in a pellet stove

4/22/14       
David Member

Warning, this is for your knowledge only!.
I do not assume any responsibility to you or the safety of your property.
By-passing any safety features and you and your home can become ash!
This is what I have discovered and repaired on my own pellet stove.

System for burning sawdust in a U.S. Stove American Harvest Model 1039; Arrived at after much trial and error.

1. Auger motor at 6 rpm to compensate for lower bulk density of sawdust.
2. Hopper agitator at 2rpm and 3 small vibrators to prevent bridging.
3. Triac in combustion blower circuit to control blower indepentent of auger.
4, Hopper extension to get 24 hour run time with lower density feed.
5. Repeat cycle timer to control burn pot agitator, hopper agitator and vibrators. This saves energy and prevents motors from overheating.
6. The 1rpm burn pot agitator motor was replaced with a 2rpm unit. This may not be required.
7. The U S Stove is well suited for this application because of the short horizontal feed auger which eliminates jamming by fines.

History:

My frirst purchase was a Corn Flame Stove to reduce heating cost for my house in Indiana. It worked well and I then purchased a Danson's Cheap Charlie for heating my house in the U.P. fo Michigan. When the price of corn went thru the roof, I started making pellets with an 8" mill. Because of the higher ash content of pellets made from a combination of sawdust, leaves and paper, the corn burner had to be cleaned every 8 hours. The mill that I have can not make pellets from straight sawdust. After seaching the web for pellet stoves suitable for burning biomass pellets, I decided to try a U.S. Stove(used model 6039) because it had a burn pot agitator.

This worked well with my home made pellets which I screened prior to burning to remove fines. Even with the screening when the hopper was nearly empty, there would be a lot of fines and smaller pellets. The auger would feed the finer material with no problem. The agaitator worked well to help the ash fall through the burn pot and running for a week was no problem.

I have now used this system for two winters burning about 25-30 gallons of sawdust a week. The sawdust is all screened through 1/4" mesh to remove larger wood chips screws.

Sawdust burning tests:

Because the fine material fed and burned well, I began seaching the web for ways to burn sawdust in a pellet stove. There are several stoves that will burn sawdust, but they are not pellet stoves. My first attemp with burning sawdust in the U.S. Stove was to empty the hopper of pellets an fill it with about 10 pounds of sawdust. Pellets were put in the burn pot and a fire started, the sawdust burned well. At the maximum auger setting there was a lot of fluidization of the sawdust and particles carried out the exhaust with sparks being visable. Bridging of the sawdust in the hopper was a problem.

Since the sawdust burned well, my next step was to evaluate the design of the 6039 stove and decide what changes were required for proper sawdust burning.
Here are the first set of changes that I made.

1. I added a agitator to the feed hopper, powered by a 2rpm auger gearmotor.
2. The bulk density of the sawdust that comes from a cabinet maker is about 1-3lbs/gal depending on the dust collector it comes from. Pellets are 5-6lbs/gal.

Based on this to get the same amount of heat, the the 4rpm auger motor would have to run at the maximum setting of 9 instead of the 3-4 that I had been running with pellets.
3.The burnpot agitator and the hopper agitator were put on a repeat cycle timer. 40 minute total cyle, 50 sec on 50 sec off, available on eBay.

This system was run for several hours. Bridging in the feed hopper was still a problem.

A vibrator taken out of a back massage pad was pop riveted to the outside of the hopper.
The vibrator was powered by the cycle timer. Sawdust flow was better, so two more vibrators were added to the other sides of the hopper. This solved the bridging problem. This system was run for about 8 hours. The air flow was still too high for the sawdust feed rate and fluidization was a problem.

A test was run as follows. The auger motor was powered directly by 110v to operate continuously.(not a good idea for a permanent setup because it by passes the safety shut down controls). Since on this stove the auger motor speed controller also controls the combustion blower speed, the setting was reduced until a minimum of fluidization occurred. This system was run for 8 hours with no problems.

The feed hopper was extended adapting a hopper extension I had for the Danson pellet burner. The lid was spilt and the agitator shaft extended. This allows filling with out removing the agitator. The agitator shaft is attached to the gearmotor shaft with clip that can be removed after the lid is raised only a few inches, the lid can then be fully opened for the removal of the shaft.

Next since the 4rpm auger running full time worked okay, ( through with the controller at maximum speed it only runs about 75%of the time) a 6rpm auger motor was installed .
To control the combustion blower a Triac speed controller was put in the line between the control panel and the blower.

This system is working well with little fluidization. More frequent cleaning of the exhaust duct is required. I clean it about once/month.
Some adjustment of the combustion blower is required based on the density of the sawdust being burned.

Further improvements
:Some type of auger speed feed contol
Feed of sawdust lower into burn pot
Almost thought about trying a Harmon, since it feeds at burn plate level. However reading about the double auger system with the slide plate and the jamming problem caused by fines changed my mind.

Cautions:

Sawdust is dust and it is difficult to keep the area clean.
My sawdust is screened through 1/4" mesh, this is necessay to prevent auger jams from foreign material. This was learned the hard way. You will be surprised at what you find.

Pellet stove is in the basement and the hopper is fed by a screw conveyor from the garage. Feed hopper has a shop vac connection for dust control when filling..

Hopper agitator: Uses 1/2" pvc pipe with screen door springs tipped with plastic hose to prevent hopper wear. Needs to be centered over the auger feed throat. Bottom bar of 1/4" plastic tube.
Springs must not be long enough to reach auger throat as they can bend down with the hopper full and can jam auger. Found out the hard way.

4/27/14       #2: Burning sawdust in a pellet stove ...
David Member

Made a mistake in this post: Should read 25-30 gallons per day of sawdust.

4/28/14       #3: Burning sawdust in a pellet stove ...
Gary

David,
What do you mean by "fluidization"? I think I know but want to make sure.

4/28/14       #4: Burning sawdust in a pellet stove ...
David Member

Fluidization is when the sawdust particle is lifted by the upward flow of the air used for combustion. This can lead to it being carried out the exhaust pipe while it is still burning.

5/16/18       #6: Burning sawdust in a pellet stove ...
cowolter

I have a multi-fuel burn pot that I can do a 50/50 corn/pellet mix but I cannot get corn cheap around here!

Some mult-fuel pellet stoves can burn Cherry pits, corn, and quite a few other items.

We also know some one that burns dried Acorns quite well!!

https://cozzy.org/best-pellet-stove/

1/14/19       #8: Burning sawdust in a pellet stove ...
Hugh Morgan Member

Website: https://diceus.com/top-software-companies-in-new-y...

Thank you for this advice!

5/28/19       #9: Burning sawdust in a pellet stove ...
Erna Clayton Member

Burning a saw dust in pellet stove well depends on the type of pellets you are using but i wont consider using it would be messy feeding the hopper with the saw dust and if mistakenly it goes to nasal or eyes will be a lot problem and won't take such risk with my health and I am using Comfortbilt Hp22 which are good for big home and I use corn wood fueled which is more convenient and don't know whether the saw dust will suit my pellet stove.

https://topreviewedten.com/best-pellet-stoves/


Post a Response
  • Notify me of responses to this thread
  • Subscribe to email updates on this Forum
  • To receive email notification of additions to this forum thread,
    enter your name and email address, and then click the
    "Keep Me Posted" button below.

    Please Note: If you have posted a message or response,
    do not submit this request ... you are already signed up
    to receive notification!

    Your Name:
    E-Mail Address:
    Enter the correct numbers into the field below:
     

    Date of your Birth:



    Return to top of page

    Buy & Sell Exchanges | Forums | Galleries | Site Map

    FORUM GUIDELINES: Please review the guidelines below before posting at WOODWEB's Interactive Message Boards (return to top)

  • WOODWEB is a professional industrial woodworking site. Hobbyist and homeowner woodworking questions are inappropriate.
  • Messages should be kept reasonably short and on topic, relating to the focus of the forum. Responses should relate to the original question.
  • A valid email return address must be included with each message.
  • Advertising is inappropriate. The only exceptions are the Classified Ads Exchange, Machinery Exchange, Lumber Exchange, and Job Opportunities and Services Exchange. When posting listings in these areas, review the posting instructions carefully.
  • Subject lines may be edited for length and clarity.
  • "Cross posting" is not permitted. Choose the best forum for your question, and post your question at one forum only.
  • Messages requesting private responses will be removed - Forums are designed to provide information and assistance for all of our visitors. Private response requests are appropriate at WOODWEB's Exchanges and Job Opportunities and Services.
  • Messages that accuse businesses or individuals of alleged negative actions or behavior are inappropriate since WOODWEB is unable to verify or substantiate the claims.
  • Posts with the intent of soliciting answers to surveys are not appropriate. Contact WOODWEB for more information on initiating a survey.
  • Excessive forum participation by an individual upsets the balance of a healthy forum atmosphere. Individuals who excessively post responses containing marginal content will be considered repeat forum abusers.
  • Responses that initiate or support inappropriate and off-topic discussion of general politics detract from the professional woodworking focus of WOODWEB, and will be removed.
  • Participants are encouraged to use their real name when posting. Intentionally using another persons name is prohibited, and posts of this nature will be removed at WOODWEB's discretion.
  • Comments, questions, or criticisms regarding Forum policies should be directed to WOODWEB's Systems Administrator
    (return to top).

    Carefully review your message before clicking on the "Send Message" button - you will not be able to revise the message once it has been sent.

    You will be notified of responses to the message(s) you posted via email. Be sure to enter your email address correctly.

    WOODWEB's forums are a highly regarded resource for professional woodworkers. Messages and responses that are crafted in a professional and civil manner strengthen this resource. Messages that do not reflect a professional tone reduce the value of our forums.

    Messages are inappropriate when their content: is deemed libelous in nature or is based on rumor, fails to meet basic standards of decorum, contains blatant advertising or inappropriate emphasis on self promotion (return to top).

    Libel:   Posts which defame an individual or organization, or employ a tone which can be viewed as malicious in nature. Words, pictures, or cartoons which expose a person or organization to public hatred, shame, disgrace, or ridicule, or induce an ill opinion of a person or organization, are libelous.

    Improper Decorum:   Posts which are profane, inciting, disrespectful or uncivil in tone, or maliciously worded. This also includes the venting of unsubstantiated opinions. Such messages do little to illuminate a given topic, and often have the opposite effect. Constructive criticism is acceptable (return to top).

    Advertising:   The purpose of WOODWEB Forums is to provide answers, not an advertising venue. Companies participating in a Forum discussion should provide specific answers to posted questions. WOODWEB suggests that businesses include an appropriately crafted signature in order to identify their company. A well meaning post that seems to be on-topic but contains a product reference may do your business more harm than good in the Forum environment. Forum users may perceive your references to specific products as unsolicited advertising (spam) and consciously avoid your web site or services. A well-crafted signature is an appropriate way to advertise your services that will not offend potential customers. Signatures should be limited to 4-6 lines, and may contain information that identifies the type of business you're in, your URL and email address (return to top).

    Repeated Forum Abuse: Forum participants who repeatedly fail to follow WOODWEB's Forum Guidelines may encounter difficulty when attempting to post messages.

    There are often situations when the original message asks for opinions: "What is the best widget for my type of shop?". To a certain extent, the person posting the message is responsible for including specific questions within the message. An open ended question (like the one above) invites responses that may read as sales pitches. WOODWEB suggests that companies responding to such a question provide detailed and substantive replies rather than responses that read as a one-sided product promotion. It has been WOODWEB's experience that substantive responses are held in higher regard by our readers (return to top).

    The staff of WOODWEB assume no responsibility for the accuracy, content, or outcome of any posting transmitted at WOODWEB's Message Boards. Participants should undertake the use of machinery, materials and methods discussed at WOODWEB's Message Boards after considerate evaluation, and at their own risk. WOODWEB reserves the right to delete any messages it deems inappropriate. (return to top)


  • Forum Posting Help
    Your Name The name you enter in this field will be the name that appears with your post or response (return to form).
    Your Website Personal or business website links must point to the author's website. Inappropriate links will be removed without notice, and at WOODWEB's sole discretion. WOODWEB reserves the right to delete any messages with links it deems inappropriate. (return to form)
    E-Mail Address Your e-mail address will not be publicly viewable. Forum participants will be able to contact you using a contact link (included with your post) that is substituted for your actual address. You must include a valid email address in this field. (return to form)
    Subject Subject may be edited for length and clarity. Subject lines should provide an indication of the content of your post. (return to form)
    Thread Related Link and Image Guidelines Thread Related Links posted at WOODWEB's Forums and Exchanges should point to locations that provide supporting information for the topic being discussed in the current message thread. The purpose of WOODWEB Forums is to provide answers, not to serve as an advertising venue. A Thread Related Link that directs visitors to an area with inappropriate content will be removed. WOODWEB reserves the right to delete any messages with links or images it deems inappropriate. (return to form)
    Thread Related File Uploads Thread Related Files posted at WOODWEB's Forums and Exchanges should provide supporting information for the topic being discussed in the current message thread. Video Files: acceptable video formats are: .MOV .AVI .WMV .MPEG .MPG .MP4 (Image Upload Tips)   If you encounter any difficulty when uploading video files, E-mail WOODWEB for assistance. The purpose of WOODWEB Forums is to provide answers, not to serve as an advertising venue. A Thread Related File that contains inappropriate content will be removed, and uploaded files that are not directly related to the message thread will be removed. WOODWEB reserves the right to delete any messages with links, files, or images it deems inappropriate. (return to form)