Firewood

[treebilly]

I'm hoping to eliminate the chance of an actual chimney fire by next winter. Central boiler seems to be the outdoor burner of choice around here. Plus I like the fact that I don't need to split as small to fit wood in.

 

[candoarms]

Treebilly,

I have a lot of experience with the outdoor boilers. Many of my friends and neighbors own them. There are some advantages and a few disadvantages.

Advantages:

Outdoor wood burning. No more smoke, ash, or soot in the house. No hauling firewood into the house and stacking it. No more carrying the ashes out of the house. The huge firebox allows for extended burn times without the need for refueling during the middle of the night. Several buildings can be heated by a single outdoor furnace, and up to 300 feet from the furnace....such as your house, garage, wood shop, chicken coop, dog kennels, etc. The size of the firewood is much larger, meaning far less splitting involved.

Disadvantages:

The furnace is now located outdoors. Often times this means moving snow in order to get to the furnace before it can be refueled. The wood pile may also be inaccessible. Plan on moving yet more snow. You'll be making trips out into the cold weather to refuel the furnace.....and these furnaces can hold a LOT of firewood. Plan on being outdoors for 20 minutes, at a minimum. This usually means dressing for the weather. The firebox is surrounded by a water jacket. The water is relatively cold. The cold water jacket is a great place for soot and creosote to build up, and when it does it forms an insulating barrier between the fire and the water, which greatly affects the efficiency of the heating system. Keeping the furnace clean is extremely important and this maintenance must be done outdoors, in the cold. No fire to watch burn indoors. The firewood is now very large and heavy. You may need special tools, or another person to help, in order to get the logs into the furnace.

I may have missed a few things. Feel free to correct me, or make additions.

Joel

 

[squisher]

I've never had one but it's been my understanding that outdoor wood boilers are a less efficient transfer of wood to home heat btu's. Therefore using more wood. I'd be interested to hear your thoughts on this?

Is it fifteen full cord a year that you go through in a boiler system?

Here I burn about 3cords a winter to heat my home. A couple more I use to heat my shop. I know it's impossible to compare wood use as there are regional differences and then the home itself. But it is simple enough to calculate btu's per cord by species and from that number you can start to figure out your daily usage.

 

[Cobleskill]

People with an OWB tell me they burn quite a bit more wood than they did with a wood stove. Gotta weigh it out I guess.

 

[candoarms]

Squisher,

We burn 13-15 full cords of firewood per season, in an indoor furnace. This is not a boiler.

I have room for two cords of firewood in the basement. Two cords will heat my home for about three weeks. I looked it up once.....the average American home requires about 100 million btu of heat per winter. I figured my rough usage and it comes out to over 300 million btu per winter.

Many years ago I did some research on the heat-absorbing qualities of different materials. I discovered, quite by accident, that water is one of the most difficult things to heat in the entire universe. It makes sense then that an outdoor wood boiler would be quite a bit less efficient.

Joel

 

[woodworkingboy]

You never much hear anyone talking about ideally burning anything less than well seasoned wood. I find it useful to ALSO throw in wood that is still of a higher moisture content. I even like throwing in some very wet Oak at times. That's in my shop where the stove is made from part of a big ol' well tank and holds a lot of wood. Sometimes it's useful to have the wetter wood burn slower and balance out the quicker burning stuff that is already in there. A good piece of wet Oak can last a number of hours and still put out heat. My shop doesn't hold heat well, so a hot stove where the wood also lasts is kind of the ideal. Nice to have a chunk of big close to charcoal in there in the morning when I get to lighting the stove again. Maybe that creates creosote, but it's not a concern.

 

[Cobleskill]

I learned from a friend that was in the fire company double wall stove pipe is worth the money it costs. He told me he had never been to a call that had dw sp.

I had several in my block chimney, not from wet wood or burning it to cool, from it being way too big to keep hot. I put dw up in an afternoon close to 10 years ago and it does not build up anything but a light powder on it.

A chimney fire is a scary thing.

 

[candoarms]

Cobleskill,

I agree with you on the double-walled chimney pipe. My outer chimney is constructed of square cinder blocks, which is then lined with clay tile. The clay tile is round, with a 7" diameter. My furnace calls for a 6" flue. I used the original chimney for the first two years, but found that I was having a hard time keeping the chimney clean. The problem was always right at the very top, where it exits the house. This is where the cold air met the smoke, creating a creosote buildup that would eventually plug the chimney.

I'm now in my 7th year with this furnace, and my 5th year with the new double-walled stainless steel chimney liner. No more problems. Double-walled liner, backed up by 1" thick clay tile liner, backed up by cinder block. I'm told that my current chimney is rated at 1700 degrees for 30 minutes. I don't know if that's true, and I don't plan on ever testing it to find out. LOL

Joel

 

[Cobleskill]

My cousin had a wood stove in his basement and an outside block chimney. He used to pull the pipe out once a week and stuff a pile of wadded up newspaper in it and light it up. Burning it off in small fires beats the blow torch of a big fire I guess.

 

[squisher]

Yah a oversized flue is no good and acts just as describes. Too much volume.

Also lets not confuse double walled stovepipe with a stainless steel chimney liner. Double wall stove pipe is used to connect the wood burning appliance to the chimney. A chimney liner is well a chimney liner and unless it's insulated it's not so much helping to keep exhaust gases warm as it is to say match chimney volume to the appliance or to increase safety due to a compromised chimney.

 

[SouthSoundTree-]

Steep roofs mean a taller outside-in-the-cold pipe, leading to more creosote buildup, and harder cleaning. A flatter roof mean as a shorter pipe, so less time to cool down and condense.

 

[Cobleskill]

My double wall starts at the ceiling and goes out the roof and up about 10 more feet. A straight up run draws a lot better than a through the wall. Looking around here most people seem to go through the wall. That should really be a last resort.

 

[squisher]

Chimney liners are used in existing masonry chimneys to help size them to an appliance and to make them safer or bring them up to code. Unless they are insulated either in their construction, by wrapping with insulation, or by pouring insulation in around them once in place they will not bring a out of code chimney up to code. Certainly they are safer. Insulating the liner, besides offering greater protection than a uninsulated liner will also give superior performance by keeping the exhaust gases warmer. A interior masonry chimney needs 2" clearance to combustible to meet code, most as in most all do not meet code yet are still built this way and pass inspection regularly. Lol. Exterior masonry chimneys require 1" clearance to combustible and again most don't meet this.

Ok another thing brought up. The theory behind burning off small amounts of creosote to prevent a large chimney fire is flawed because of pyrolyzing. This is the process by which wood starts to change chemically through exposure to heat. It becomes more flammable each time it's heated. That is how a setup that has burned fine for decades can one day.....whoosh! Burning creosote out of a chimney even in small amounts is not a sound practice. The proper way is to cure what is producing the heavy creosote in the first place. Setup? Wood? Burning practices?

Jay in your big old smokey barrel you may not have any performance issue with throwing the odd chunk in but all that is doing is creating more smoke and creosote. In a modern efficient setup it would probably cause the appliance to not function properly and of course, smoke and creosote. Sorry but there are no pluses to burning unseasoned wood. The extended burn time you're looking for would be more effectively achieved by being able to control the air better.

 

[candoarms]

Speaking of chimney fires..........

When installing my furnace, I was told that I would need to install a draft regulator. We've all seen these things. It's a device that it is mounted in the flue with a swinging door that opens and closes as the wind blows. The door opens when the draft vacuum is too high. This prevents gushes of air from entering the firebox. It allows for an even burn temp and a controlled burn time.

Several websites warned against installing a draft regulator, due to the possibility of chimney fires. When the chimney catches fire, it creates a huge draft. The draft regulator will swing full open, allowing as much air to enter as the chimney fire is calling for. This creates a jet burn in the chimney, which can reach extremely high temperatures.

So here's my solution. I installed the draft regulator as recommended by my furnace manufacturer. But I also installed an emergency latch that can be used to hold the draft regulator's door tightly closed, if needed. I also purchased two chimney fire extinguishers, called Chimfex. In the event of a chimney fire, the idea is to close off the draft to the furnace completely, thereby eliminating or reducing the oxygen source to the fire. Open the furnace door and toss in a Chimfex fire suppressor, then quickly close the door and latch it. The Chimfex flare will extinguish the chimney fire.

Both of the following videos are worth watching.

https://www.youtube.com/watch?v=mcw1qx7t1ig

https://www.youtube.com/watch?v=e1hfVvcxh-w

Joel

 

[squisher]

My double wall starts at the ceiling and goes out the roof and up about 10 more feet. A straight up run draws a lot better than a through the wall. Looking around here most people seem to go through the wall. That should really be a last resort.

You are correct. A double wall interior chimney is probably arguably one of the most efficient and safest set ups. Running straight up from the stove with no 90's and staying inside the building envelope for as long as possible is the best way.

Let's not confuse masonry chimneys with metal chimneys. Two different animals entirely.

 

[sotc]

Here's my current pile, 5x5x28.

 

[stig]

That is 'bout half of what I use in a year.
If it is all hardwood, that is.

Sometimes I think of how much wood I've cut and split and run through the boiler in the 20 some years I've had the place.
Then I quickly try to think of something more pleasant

 

[sotc]

It's mixed. That should heat my house, my father in laws and my shop I expect. Can't wait to build my wood shed!

 

[brendonv]

I was all excited to find out now much wood i use this year. In the past id just pull from the circle pile. This year i cut and stacked for the first time. I think it was like a little over 5 cd under the timber frame.

Things were super warm and i barley used half of my pile plus another cord of mixed crap.

 

[candoarms]

Brendonv,

You've got a very nice stack of wood there. If you're like me, you almost hate to burn it, because it looks so nice all stacked up like that. But, like I always say, "I'll do it again this year". LOL

Joel

 

[treebilly]

Well you got me thinking I'm gonna do more research before changing things here. im thinking maybe I need to look into what I have and see what I can do to make it better. Maybe switch to a new Eco burner. My brother loves his. One issue is I'm not home to control the burn. My wife, as much as I love her, can't tend a fire for shit. She either forgets about it, or loads it up and shuts it down to smolder. I got a clay liner so that doesn't help either. I burn hot while I get ready for work to get things warm and will climb up once a week and run the brush through it.

 

[Dave Shepard]

I have a Central 6048 Classic. They are not allowed in many places anymore. An E-Classic gasifier is also good, but you have to have good dry fuel, but you use much less. I burn a lot of wood, but my house is almost uninsulated. Last winter I burned over 40 cords of pine slabs and about four cords of hardwood firewood. It's nice to get rid of the slabwood for "free", but it took about three hours every weekend to process slabs, and five minutes twice a day to fill the furnace. I know it was less than five minutes, because my motion lights would come on, and I could put a full load in the boiler and be back in the house before they went off.

 

[gf beranek]

Wood stoves are banned in a lot of urban areas now. Least here in Cali.

 

[treebilly]

Luckily I'm still rural. Farms are disappearing though around me.

 

[woodworkingboy]

Squishy, you are likely very right about my stove and inclination to burn green wood sometimes. A modern efficient stove would be better for controlling the heat as you say, I have no doubts. Then again, I'd probably be hesitating to smoke and grill all kinds of meats and stuff inside and outside of it, get it covered with grease and things I can't remember why. You'd be surprised at all the helpful things that fatty can do for me, and it can get to looking pretty exotic. I see the real expensive highly engineered stoves in the stove shop, nice yes, but they make me chuckle a bit. I can clean out the ash from mine with a big ol' shovel too. My stove has gone through varies phases of rebuilt, and it's been heating my shops for over thirty years. Don't you have to speak French or something to buy a stove these days?