Chimney For Wood Stove

I put this system in back in Oct. It has the insulation between the first two layers. I would not recommend modifying a chimney. Though the insulation is a great idea, there are other variables like the characteristics of the metal and the ventilation design of the air spaces in the chimney.

While I do like the concept, I believe that you're adding the insulation in the wrong donut cylinder. The inner layer of sheet metal gets up to temperature faster than ceramics because it is a smaller total mass. By putting another material in contact with this sheet metal you'll be increasing the thermal mass initially getting heated. The rate of heat transfer from inside out will be nearly identical, regardless of which layer has the insulation. Additionally by having an air gap in the next region from the hot gasses you will be capable of making this sleeve easily replaceable.

Now here's a neat deluxe model idea you might also be able to add. I expect that this air gap would be a sealed top and bottom cavity. At or near the top of this cavity a carbon monoxide sensor could be added. This will alert the owner when a new inner sleeve will be needed because a hole has formed in this sleeve.

I warn you though about all vermiculite, a lot of vermiculite have asbestos in it. http://www.idph.state.il.us/envhealth/factsheets/vermiculite.htm

Good point on the outer ring as being the one to add he insulation to.That does indeed make more sense.

And yes I know about the asbestos in vermiculite. That's why I was finding other alternatives. But was wondering if the concept was sound in the first place.

Now here's a neat deluxe model idea you might also be able to add. I expect that this air gap would be a sealed top and bottom cavity.

Actually, it is a semi open pathway, so cool air can flow with a chimney effect to help keep it cooler by the time it gets to the next layer. So on second thought then maybe it till is better to keep the insulation on the inner doughnt, and leave the outer one still air flowing ya know?

The key for best performance of a chimney is to keep the gasses inside as hot as possible, to maximize available draft.

I don't agree, the best performance of a chimney is to emit as much heat as possible so the gasses leaving are as cold as possible. THis means you get most energy from the stuff you are burning.

All this about creosote build up is just a by-product of poor design that you have gone along with.

cnc jim

I would also agree in theroy about this also. But the stove is old, does not have converters, or special burning configureation. So un burnt creosote does indee go up tht chimney. AND A LOT OF IT!!!

Becuse if the fire was a cool bad start, there will be ooo much being eposited on tht col pipe that it will start runnng don the ids as a liquid even. And i mean a LOT.

Then change the stove out!!!

A good stove here can cost upwards of $1000, but its a good investment in efficiency and air cleanliness as well as saving money and work in the long run........as well as making the chimney system simpler and cheaper.....

I am sure that inventors in the USA have not been standing around idle.....

Start here:-

http://www.epa.gov/burnwise/woodstoves.html

Then change the stove out!!!

Easier said than done.

A good stove here can cost upwards of $1000,

Yes maybe there but not here. Here a good quality stove as you describe, costs well over 2000 and some up to 4000. thats 25% of my yearly income.

but its a good investment in efficiency and air cleanliness as well as saving money and work in the long run........as well as making the chimney system simpler and cheaper.....

At least read andys posts and have a look at a new stove. We would all rather help you get the most bangs for bucks on a new stove, or modify yours so it burns better, you are warmer, and you need less wood, than just help you struggle with your creosote woes, i think.

CNC jim

What I completely forgot to mention is that Creosote can cause dangerous explosions inside older wood burners and bad fires in chimney systems.

I looked here and found disturbing statistics for chimney fires:

https://www.csia.org/HomeownerResources/ChimneySafetyInfo/ChimneyFireFacts/tabid/126/Default.aspx

There are plenty more websites on the subject of chimney fires.

I have been heating with wood for more than 1/2 of my life, (54 years old now) so fully aware of all the dangers.

Just trying to make a more efficient system with what I got.

Joe

So we can see why he's trying to solve the problem, but the solution isn't a new stove, by the sounds of it

Nowadays, we go about this slightly differently here.

Firstly, the wood burners are so designed nowadays that they burn the total wood, including the creosote and similar so that you see no more smoke expelled. Therefore the types of chemicals that would build up in the chimney are reduced to a tiny proportion of what an old fashioned wood burner produces.

Regular cleaning gets rid of any deposits.

Smoke and heat are both wasted energy and contribute to making air dirty, Germany (and Austria) are busy making laws to stop this. Also electronic smoke scrubbers will have to be bought and installed for burners that do not achieve clean burning. These scrubbers cost more that a clean burning fire does!!!

Now there are also wood burners that have a flame above and below the wood, burning the fuel as good as 100%, no smoke, but a lot of heat, see here:-

http://www.energieportal24.de/fachberichte_artikel_226.htm

If the exhaust is cleaned of all damaging chemicals through complete burning, you can accept a lower temperature in the chimney as they is nothing to distill out, this improves the effectiveness dramatically.

A good well adjusted fire can run effectively with an exhaust temperature as low as 100 - 140°C.

A study of a few years ago in Austria demonstrated that it only needed one house with an older smoking type wood burner and the air quality for the whole region gets dramatically lowered....

Burning pellets is also a good way to go to keep efficiency high and dangerous smoke particles to a minimum.

My tip is look for a really efficient burner and then the other problems discussed here will be dramatically reduced or even erased. Plus the wood usage for the same comfort level can be halved.....

Best of luck.....

Now an interesting project for this summer will be to make this stove indeed burn more efficiently. This is that salvaged stove that i re finished remember those postings from last summer? it looks like this before and after, Now I wonder what I can do to it to make it better?

Well what does it look like inside? is there any info in the old thread? What was it called?

Not a lot to the stove. no names or anything on it. It is built like a tank. It probably weighs close to 300 pounds. It has stamped on it a 1978 date, but thats all. Some locals that have seen it say it looks like a "Kickapoo Stove Works unit"

It is double walled. Thick like 1/4" thick steel panels, NOT cast iron. the inner firebox is surrounded by another layer, and the blower underneath blows air between the two layers, so the heat can be ducted where needed.

The top fitting in that photo is the hot air ductwork connection. The chimney connection comes out the rear of the stove. Which is a 6" round exit. This goes into a 6" to 8" adapter because the chimney is 8" (existing chimney in the house)

The firebox is ultra simple. roughly a cube, no baffles or anything just more or less a cube. the chimney exits at the top of the rear wall of this cube. A cast iron grate floor, that has slots in it that allow the ashes to fall into catch tray that is below the grate floor.

There are no dedicated "Air" mixture intake places. If extra air is needed slightly pulling out that ash catch tray can be done.

Thing is I don't dare do it. give it extra air that is.

Burning mixture of Oak, Maple, Elm, Ash, nice hardwoods, that have been seasoned for few years.

But to run this beast, as suggsted in an earlier posting, to run it fast,clean,and hot, I'd have to live sitting right next to it, and feed it a constant supply of pieces of wood about the size of a 2 by 2 at the most. Anything larger and the thing will be overfired in no time. It would get soo hot both the stove AND the chimney that youd just be waiting for the house to burn down! And it's not that youre stuffing the wood in too fast either. because there is a when burning hot & clean like this it needs a LOT of wood quickly, if you try to slow the fee of wood down you loose your fire and it goes out and you have to start a new fire all over again. Pieces too big,,, or pieces too slow in the amount of wood you feed it, either case and your fire goes out.

A nice be of embers and large pieces of wood, 4 by 4 and larger, is what his stove loves to run on. You can pile them in and damper it down, and it will run for hours.

But only if it's dampered down. if it is not dampered down it will run soo hot that the house WILL end up burning down.

It can run hot clean and fast, but only if you re feeding a 2 by 2 piece every 5 minutes or so. Any fster feed it gets too hot. or you gotta damper it down.

Fantastic info. I'm surprised there aren't more comments. One thing that I wonder:

This goes into a 6" to 8" adapter because the chimney is 8" I know you were looking at the chimney when we interrupted you, I guess the flue is meant to be 6" all the way up, you will be losing some speed of exhaust gasses going into 8 inches all the way, could this be affecting the resin deposit on the chimney wall? So not just heat, but speed as well. And although I can't understand why, I imagine it affects the burn rate.

If there is no valve in the chimney side, that's why the ash tray has such an effect, there's that big potential suction on the other end.

A lot of stoves do have baffles in towards the top, and apparently it is to mix the gasses with air, and this produces a secondary burn, - more heat less resin. Some have small vents at the top as well, for the same purpose.

It seems to me that your stove would be better used heating a massive property, you seem to say that it works best when it is giving out too much heat for you. Are you sure it's not just too big?

I did come across this, which may be of no interest

http://www.homesteadingtoday.com/showthread.php?t=328867

cnc jim

Hi NNS,

You have a beautifully restored wood stove. And a bad creosote problem.

First, I believe the most important factor affecting the rate of creosote buildup is the moisture content of the wood. This moisture condensing in the chimney is the cause of the creosote buildup. Some say oak should be seasoned for two years. Dry wood also burns hotter.

Next, prevent condensation by burning a hot fire. I learned the hard way during some moderate weather that throwing on a log once in a while and keeping the air intake damper nearly closed will gunk up, even an insulated chimney fast. (this is with a brand new EPA and State of Washington approved stove) I won't make that mistake again. I don't even damp it down at night anymore. I give it plenty of air and wood and let it burn hot. The fuel may burn up sooner but since it has burned more efficiently I get more heat in the long run and there's still enough embers to start a fire in the morning.

I used to live in Australia and I installed wood stoves (space heaters) in two of my homes. A heater where i live now is not required but there are wood burning ovens here. Single skin chimneys seem to work just fine in the tropics it seems.

Now, the heater chimney traverses two zones on its way to the ether interface.. There's the bit inside the house upto the ceiling and the rest through the ceiling, roof void and up.

The bit inside the house was a single pipe, from the ceiling up was a coaxial.

The single pipe inside the house would glow red hot and allowed for energy recovery into the area to be heated. It wasn't red hot closer to the ceiling. The dual skin above the ceiling kept the flue hot enough to promote a draw and also protected against fires of adjacent combustibles.

Red hot in the lower section made sure that the creosote et al totally burned off. The exhaust smoke was a heat haze, very clean once it was going.

I had a perforated cage round the single skin chimney inside for safety.

All stainless steel.

When the fire was stoking along the chimney would sometimes howl or reverb like a trumpet with the gale being drawn through it. Kinda like a whistling kettle....it let you know when to choke the fire off and damp the flue for a nice efficient slow burn with everything at optimum temperatures.

I don't think a triple skin would be more beneficial than a better double skin arrangement. Complexity for little or no gain is my take on it.

Could someone tell me what brand this pipe is and what are the flue dia is ,And outside wall dia Is, thanks