iDRY Vacuum Kilns

Sponsors:

Wood Stove Question

Started by Kcwoodbutcher, November 12, 2006, 08:46:21 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Kcwoodbutcher

What is the relationship between the damper setting and the air intake setting on a wood stove? I'm trying to get the most efficiency/longest burn time out of my old pot belly stove.
My job is to do everything nobody else felt like doing today

logwalker

That is actually a difficult question to answer accuratly. I have heated with wood almost exclusivly most of my life and still don't know the best way. The simple answer is it slows the fire down and lowers the stack tempertures. Once you shut the damper it doesn't make much diiference where you have the intake as long as it isn't closed completely. I leave mine wide open and give it all the air it wants and regulate with the damper. I would recommend very dry wood if you are going to do it and check often for creosote buildup. LW
Let's all be careful out there tomorrow. Lt40hd, 22' Kenworth Flatbed rollback dump, MM45B Mitsubishi trackhoe, Clark5000lb Forklift, Kubota L2850 tractor

Michigan Mike

I don't claim to be an expert but have heated with wood for about about 30 years.  It isn't just the air intake and the damper but also how good  a draft you have. My barn stove has excellent draft I can almost completely shut the damper and leave the air intake open and the fire still  burns pretty much full. The house stove requires the damper be wide open draft obviously not as good. The house stove does have a catalyst  inside the stove that acts as an intrenal damper but there is no adjusting it. It is either on or off. I will be real interested in the rest of the reply's you get. I think it is more of an art than science.

Sprucegum

My glass-doored fireplace has no damper at all , the fire is controlled by the air intake. Seems to work pretty good.

beenthere

I'll agree with all three responses. It's an art you learn, and will depend on the wood, the draft, the stage of burning (early no coals, later with hot coals), and the tightness of the stove.  If it burns too fast, close it down. If it smokes back, open it up.  And enjoy everything in between to get the heat and length of burn that you want.
Enjoy. :)
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Bill

Tough question to answer well.

That said here's some of my past experience for what its worth ( which by the way is sometimes measured by what one pays for something  ;D  ).

Many years back I had no damper on my air tight Fisher papa bear ( their largest single door model ) . The air intakes on the door were its only adjustment. I used to burn a mix of dry and wet ( well recently cut ) wood to get an overnight burn. I would regularly have to clean the creosote out of the chimney because of the slow/low burn temps I was creating. To get the overnight burn I turned the air practically off - maybe an 1/8 or 1/16 of a turn of one intake open. This gave enough for the dry wood to burn and the dry wood burning would drive the moisture out of the "wet" wood which would then burn. I learned to tell the right "setting" of the intake by touching the chimney pipe, how hot it was and how much smoke there was outside. There was sufficient draft there and the "air tight" stove meant a damper wasn't needed ( though a chimney fire would probably be better contained if I had both ).

Now I have a glass door not quite airtight stove that sits in the front of the fireplace. It has a thermometer in the top so I don't burn my fingers checking the chimney anymore and has made it much easier to check the burn temp. The air intakes are also the only thing I have to adjust this stove also.

Now up at the cabin ( not really mine but close enough ) . It has a not too old wood stove with both a damper and air intake. It needs both to throttle it back as the air intakes / stove are not tight enough to keep air out - so it needs the damper to assist.

Ahh - but now you ask what the heck did he just say - so let me try to explain the adjustment.

If the wood is green ( wet ) you probably want more of air.
    "       "          dry               "                  "     to cut back the air.

If you want the wood to last    "                  "           "                ".
If you want to avoid overheating the chimney because there's alot of creosote cut back air.
If its raining and you have a tight chimney and a little creosote you may want to tempt a chimney fire ( are you on good terms with the fire dept and is your fire ins paid up ) you may want to burn off some chimney creosote ( and the house down ) open up the air but stand there with plenty of good chimney fire suppression equip till you cut her back.

I believe a flue thermometer will help you get temps right after some experimentation. Some like to see little to no creosote in the chimney as a sign the temps are right but I think creosote is also affected by how wet the wood is and the type of wood ( there's more in the evergreens than the hardwoods ). BTW - for years I never used a flue thermometer but then I had a free supply of wood so I wasn't trying too hard.

You'll need to adjust temps for older chimneys or "loose" ones accordingly. Even new "tight" ones can crack and draw outside air from seams if you start a roaring creosote chimney fire ( out of control ??? ) so caution is the watch word.

Careful out there  . . .

Paschale

Quote from: Bill on November 12, 2006, 11:32:21 PM

I believe a flue thermometer will help you get temps right after some experimentation. Some like to see little to no creosote in the chimney as a sign the temps are right but I think creosote is also affected by how wet the wood is and the type of wood ( there's more in the evergreens than the hardwoods ). BTW -

I just installed a woodstove in my shop, and I'm really looking forward to using it this winter.  I've heard/read that one should avoid buring pine and the like because of the likelihood of creosote buildup, but a guy at work who heats his house partially with a woodstove says he'll use well seasoned softwood in his stove, and here I see you mentioning evergreens.

How many of you use softwoods in your woodstoves?
Y'all can pronounce it "puh-SKOLLY"

thecfarm

I do burn pine and hemlock slabs in my stove in the basement,but I let these dry out for at least a year.I use to burn a lot of pine that had died standing in the woods.Don't last long,but I did get some heat from it.By the way Paschale,the white pine that I burn does not coal down.Once the wood is gone,the fire is just about gone too.Don't know if you can get hemlock or not,but this will coal down pretty good.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

rebocardo

http://www.woodheat.org/lore/firwdsong.htm

T H E   F I R E W O O D   S O N G
(sung to the tune of "I's the b'y that builds the boats")

I'm the guy that cuts the logs,
And I'm the guy that splits 'em
I stack the wood in nice straight rows,
And wait six months to burn 'em.

The sun, she warms my firewood pile,
And drives out all the water,
The wind blows through there all the while,
And carries away the moisture.

Bless the sun and bless the wind,
They make my wood much drier,
If they didn't have time to do their job,
The pile would be far higher.

My chimney don't fill up with soot,
My pipes don't drip black water,
I'm better off to burn dry wood,
Keeps me warm all through the winter.

I'm the guy that cuts the logs,
And I'm the guy that splits 'em,
It costs me nothing to get 'em dry,
The sun and winds assistin'.

(Armstrong/Gulland 1983)



logwalker

The dryness factor is absolutely the key to success with the traditional stove. It is my understanding that you need moisture to build the creosote in the stovepipe. I am not sure that is true but it does seem to hold true in practice.

As far as the hard or soft wood question if the wood is dry it will burn without build up. I have gone years and years without cleaning my flues as it just was not needed. I did check periodically. It helps to burn a hot fire every morning after banking overnight to keep the flue clean. Getting the right size stove is important too. Too big is not good.

American Heating systems sells a furnace/boiler that they suggest you burn damp to wet wood in for good results. They are reaching 2000 degrees in the secondary chamber and injecting air for a complete burn. They claim flue temps as low as 250 d. If I can swing one someday I think I will get one. LW
Let's all be careful out there tomorrow. Lt40hd, 22' Kenworth Flatbed rollback dump, MM45B Mitsubishi trackhoe, Clark5000lb Forklift, Kubota L2850 tractor

Michigan Mike

Hey Paschale I burn just hardwoods in the house stove but the barn stove usually gets softwoods. The uses are different the house gets heated 24-7 the barn just gets heated when I am working out there. The softwoods burn out quickly and I don't have to leave a fire burning when I am through working. I also think I get heat quicker with softwoods. Hope this helps .

leweee

Quote from: rebocardo on November 13, 2006, 06:59:00 PM
http://www.woodheat.org/lore/firwdsong.htm

T H E   F I R E W O O D   S O N G
(sung to the tune of "I's the b'y that builds the boats")

I'm the guy that cuts the logs,
And I'm the guy that splits 'em
I stack the wood in nice straight rows,
And wait six months to burn 'em.

The sun, she warms my firewood pile,
And drives out all the water,
The wind blows through there all the while,
And carries away the moisture.

Bless the sun and bless the wind,
They make my wood much drier,
If they didn't have time to do their job,
The pile would be far higher.

My chimney don't fill up with soot,
My pipes don't drip black water,
I'm better off to burn dry wood,
Keeps me warm all through the winter.

I'm the guy that cuts the logs,
And I'm the guy that splits 'em,
It costs me nothing to get 'em dry,
The sun and winds assistin'.

(Armstrong/Gulland 1983)




rebocardo..... Thanks for posting that little dide. 8)
                      Catchy little tune :)
just another beaver with a chainsaw &  it's never so bad that it couldn't get worse.

Weekend_Sawyer

I burn everything but I make sure it is dry before burning it.
I have 2 wood stoves and a fireplace.
I clean my chimnys once a year and notice they are not too built up with creasote.

My woodstove only has an air intake, no damper. I could put one in but it just doesn't seem to need it. I also put a thermomiter on it. It has 3 areas on it creasote, good and overburn. Works well.

Jon
Imagine, Me a Tree Farmer.
Jon, Appalachian American Wannabe.

Bill

FWIW -

I found this little gem about creosote to help explain it :

"
Creosote is a gummy, foul smelling, corrosive and inflammable substance that, if no precautions are taken, will coat the insides of everything it passes through. It is formed when volatile gases given off in the burning process combine and condense on their way out of the chimney. 



The  gases  leave the burning wood with the smoke. If the smoke is cooled below 250 degrees F, the gases liquefy, combine, and solidify, forming creosote. Creosote takes several forms, all bad. As a liquid, it can run down the insides of pipes and chimneys, oozing out of any openings. It can form a hard layer coating the insides of pipes and chimney liners. It can form into a fluffy substance that plugs pipes and breaks off and falls down, filling low spots in piping. It is the cause of most chimney fires and the main reason chimneys and pipes have to be cleaned and inspected periodically. 
"

Using dry wood is typically acknowledged to help avoid it but keeping flue temp's above 250 seems to be real important. Still I'd burn most any wood I got for free - be it evergreen or hardwood .

I typically had creosote form where the insulated metal pipe hit outside air ( like 0-32 temp ) which made it the perfect place for creosote to form. The experience part came in for me to balance the flue between 250 or a little more and not setting the structural members of the house on fire and especially not starting a chimney fire . Now the cabin stove - you can't throttle it back far enough to get cool chimney temps - so it doesn't see much if any creosote.

Hope this helps . . .

rebocardo

I think the damper on the front is there mainly to prevent overfiring, especially if your house has good draft, or to shut the stove down completelty when leaving the house or in case of a chimney fire. Even with the flue in the closed position, on my stove it can still suck enough air to fuel a good hot fire.

Thank You Sponsors!