OT : Creosote

Maybe someone on here has some insight on this one... I heat my house with a Clayton 1600M woodburning forced air furnace. Due to my work schedule during the winter (12+ hour shifts) I have to fill the stove with wood and damper it way down so it lasts until I get home. This causes the stovepipe (triple wall stainless) to build up creosote. I know this isn't an ideal situation, but it's the reality right now. Anyway, I took it all apart and cleaned it today. The single wall pipe that connects the furnace to the triple wall, I take outside, stand it up and light it to burn all the creosote out of. It works great and comes out spotless. For the first time (this is the second year), I couldn't get the creosote out of the triple wall. The buildup is very bumpy. At its thickest parts, it's maybe just a bit more than 1/4" thick, and inbetween the bumps it's about 1/8" thick. It usually brushes out easily, but today I scrubbed and scrubbed with the wire brush and it won't come out. Some of it just turned to dust, but that was it. The stuff is so hard I couldn't scrape it out with a screwdriver. What the heck is this stuff? How do I get rid of it???

You answered your own question, it is creosote or the byproducts of incomplete combustion of wood. A mixture of organic resins, oils, fatty alcohols, and carbon. Highly flammable. If this partcular mix is tougher this year than others it could be the particular mix of wood.

Based on the conditions you are describing, Im thinking a good cleaning from a pro followed by a change in technique. I understand your work schedule so the technique change needs to be with the stove. Can you use some other heat source during the day? Even just enough to keep the pipes from freezing then build up the fire when you get home. Saving money on heat doesnt accomplish much if the house burns down from a chimney fire while you are away.

Maybe glazed creosote? Is you chimminy inteior or exteior? There is alot of answers to your question. Call a chimminy sweep.

your closing the damper may be your worst enemy try closing stove drafts only and open each eve.for a hot fire until you stock it for the night then close drafts for the night re open drafts soon as you get up in the morning til you stock before ya leave for work

Interesting problem. I've got two wood furnaces going all the time. One heats my house and the other by workshop and barn. Both have superinsulated Canadian stainless pipe. I don't know how much difference that makes, but the Canadian specs are better then the USA specs. Much higher burnout ratings and much more insulation, so the pipes stay hotter. I had trouble buying it here in NY.

I always get that thick, rock-hard creosote layer on my single wall pipes down low that connect the furnaces to the the stainless - but never in the stainless itself. I have to break it out with a pry-bar or screwdriver.

How often do you let your chimneys run real hot? That might be the difference. Since mine are run in turned-down mode a lot, I make sure I overfire them at least once a week. When I do, often the main chimney starts to ignite (the creosote inside it), so I've got to be careful and damper it down when it does, and keep it in control. I'll add though, that my system is virutally fire proof. I wouldn't do the overfire in a questionable chimney. It is also the reason why so many chimney fires start on Christmas. People chuck their wrapping fire in the furnace or stove, and it flashes so hot, the creosote in the chimney catches fire.

There's no getting around the fact that old-style furnaces like your Clayton, or my Woodchuck and Thermocontrol 500 are only efficient when being run with a hot fire, and are going to soot up when run with dampers near closed. You have to compensate somehow.

I'm also wondering about your wood. If all your wood hardwood and it all well dried? I had some bad creosote problems years back when I burned red oak that only seasoned one summer (here it needs two summers). Also, soft conifers like pine, spruce, and hemlock will also gum it up.

I have my doubts that a chimney sweep is going to help with rock-hard creosote. But who knows? Explain your problem and ask before you pay someone to make the trip to your home.

The old timers used to run their fires red hot once every day. Some even threw accelerant in there to make it flash. And, that was with crappy chimneys.

I'm not sure what you can do to clean out the creosote unless you can burn it out like you do with the other pipe. As mentioned, avoid burning much pine , spruce etc as that will produce alot more creosote than good dry hardwood. Try to burn all dry well seasoned hardwood, and letting the chimney get hot when you first start the fire will help too. I have a oil/wood combination furnace and though I use all wood when it gets freezing or below at night, I have found that running the oil burner occasionally helpps dry out the creosote so it breaks up and cleans out readily. There is also a "chimney sweeping log" product that you can use that is supposed to dry out and break up creosote- Ive never tried it but seen it in the store- not sure how good it is.

My dad and I used almost identical Longwood furnaces for 25 years. His house and flu were built 5 years before mine and he had a lot of problems with creosote buildup. His flue was masonary liner with cinderblocks on the outer. Mine had a different type of block that had hollow spaces. The man that built it insulated these spaces with a type of vermiculite. Mine never creosoted up. We partially cured my dads by wrapping fiberglass insulation around it in the attic area. The attic being cooler was where the problem was.

Prevention meausres are to keep the flue hot, and burn year old, seasoned wood.

You being gone during the day is the problem.

could you get some sort of a timer system that would periodically open the damper and let it burn a little hotter, then close it back down?

Good luck, Gene

Walmart here carries the Chimney sweeping logs and Ace Hardware does also. Actually I am looking at one now and it says Creosote Sweeping Log for wood stoves and chimneys. wwwcleanyourchimney.com. Have used them for 10 years and they work. You will probably need several to crystalize your buildup Henry

Been heating with wood over 39 years and I can tell you that creosote is one hinderence to wood burning. For the past 38 years we use CREOSOTE DESTROYER DAILY in out wood furnance. Works great, reduces glaze to brown powder,Just follow directions on the tub and I can tell you it works. Even tried potato peelings,didn't hurt the pipe but used it when we run out of the destroyer. wouldn't put my faith in potato peelings alone.We get ours from menards.
Hope this helps LOU

How do you compensate on your 500? Do you let the inlet damper close all the way? As I said the other day, I put a clip on my damper so it cant close all the way, the damper flap is always open about a 1/4 inch when the automatic choke spring, as I call it closes the damper. Dosent that metallic spring in there remind you of a automatic choke spring on a 70s chevy/carter, carburator?lol I used a inner fender or sheet metal clip, the kind you find on 70s 80s GM trucks that a has threads for a screw to go into it, on the damper. The clip I slid onto the damper, and the threaded area acts as a stop to keep it open some. J

To answer a few questions:
I've been burning only seasoned hardwood, mostly maple and cherry, with a bit of ash. During the day, I close the air drafts on the stove and the damper. Otherwise it won't make the 12+ hours until I get home and it gets wayyyyyy too hot in the house. Even with it choked back all the way, it's not uncommon for it to be 75+ degrees in here.
Unfortunately, I have no other heat source. The wood burner is the only way to keep the house warm.
My stovepipe is Simpson Duravent 6" triple wall stainless. The OD is 10". It runs up the outside of my house exposed. I guess if it were enclosed it would stay warmer and maybe not get so gummy.
I try to get it hot every couple days, but after it starts to get creosote in it, it makes me nervous to do that. I'm afraid I'll start a chimney fire. I figure that if I just keep it burning slow, the odds of it catching are lower.
Tractor Supply sells some creosote eliminating additives, but the owners manual for my stovepipe states explicitly to avoid using them due to their corrosive nature. I don't know what's worse, lots of creosote, or a corrosive additive. Any input on this topic??

Creosote is unburned fuel going up the stack and wasted.
You have turned your furnace into a coke oven.Where biomass is heated in a low oxygen atmosphere where flammable vapours can not burn.
The stack runs cold which provides a place for the fuel gasses to condense.
Lots of carbon monoxide gas too which trys to find it's way into the living areas of the house. Anybody tired or have head aches.
There is no fix. All you can do is stoke the firebox and open the air inlet enough for clean combustion. The fire will burn it's self out mid day.That is better than a chimney fire and burning the place down.
Either let the place cool off or use LP, oil or electric backup heat.It's what I do here.

(quoted from post at 05:08:47 12/21/09)
Lots of carbon monoxide gas too which trys to find it's way into the living areas of the house. Anybody tired or have head aches.

Click to expand...

I'm tired and have headaches everyday... but it's work related. I have a CO detector in the house.
I realize the stack is going to get creosote. In the past it's always brushed out easily, but this time it's like concrete. That's my real question. What's different this time?

You have a problem now, don't know what to advise for that.

You need to burn a hot fire every once in a while, if your house gets 75, then put less wood in, and stoke it up when you come home, if it's a little cool so what, use that time to burn a hot fire & get it hot.

But - you gotta get things cleaned up first.

--->Paul

Hey there;
For what its worth, my Mom,(an old country
Italian) used to throw a handful of common
table salt, on the fire, every once in a
while. She said that it helped to prevent
chimney fires. As I was only about 6-10 yrs.
old at the time,(I'm 76 now) I cant remember
if it really worked or not, but you might
check it out.
Bob
God Bless

I've used woodstoves all my senior citizen life, the way you describe what's in your stainless steel chimney sounds like you haven't got that part hot enough to change to dry soot. The only thing I have that gunks up is the cap on top of my chimney. I take it down a few times a year, put it at a safe distance from anything, pack it with newspapers and burn the gunk off. After it's burned it bubbles up and is dry, easy to get rid of. Sounds like your stainless steel hasn't been hot enough for this process. Don't know of an easy safe way to do it if it's in its installed place, but it sounds like you need to purposely run a hotter fire in your stove while watching it closely, then use a chimney brush.

I would think being outside the house exposed is the biggest problem. Flue stays cool so the gases cool down going up the flue and start to build up in the pipe. Is it possible for you to build a chimminy chase around the pipe and insulate it with vermiculite? Also if your house gets that hot, is you stove to big for the house, dampering it way down, to avoid overheating your house is also causing you the glazed creosote buildup on the outside exposed chimmny.

I would like to put a big second on what Jdemarais told you. I was on the fire dept for 35 years and our chief of thirty years used to always preach "Have a friendly chimney fire every day" You do this by putting in kindling wood and getting the fire to burn up into the flue where it will ignite the creosote. This needs to be done judiciously as J said. You need to keep it from going too fast by keeping your hand on the damper. It can't burn without air. Once you have your accumulation cleaned out with a slow methodical burn, you will be able to clean it quickly every day. You need to be aware also that as creosote burns it expands to about three times its cold size, this is why a burning chimney roars so, it is the air being sucked through the narrowed stretch of pipe. If you have a tee you can insert A mirror to inspect regularly. Then you will be far safer than those people who have their chimney cleaned in the fall and think that they are good for the year regardless of how they burn it.

I suspect your main problem is a cool chimney and wood that is not dry enough.

I realize you said your wood is seasoned, but that word means different things to different people.

Here where I live in New York, hard maple, hickory and red oak will not season properly in one summer. It looks fairly dry with the typical radial cracks, but will not burn near as clean as it should. On the other hand, ash and soft (red) maple, along with beech can dry fine in one summer if the sun ever comes out.

I don't know where you live and how long your summers are.

About the pipe. Most pipe sold in the USA is inferior to what is available in Canada. And, often it's made by the same companies. They just make two versions and are reluctant to cross borders. I had a heck of time getting Canadian pipe into New York. I use Selkirk Sentinel CF that has two inches of real insulation, not just air space. 8" ID and 13" OD. It came out in 1982 to meet the new stricter Canadian chimney standards (much stricter than in the USA). For an overburn rating, it is rated at 1700 degree F for a full hour, which is pretty amazing. The CAN4-S629-M84 specs are very rigid against cool pipe and burnout ratings.

I went through the trouble to get it since we too have a large wood furnace that gets turned down a lot. So, I needed a virtually fire burnout proof chimney that I could run hot to burn itself clean. Also, since it's so well insulated, it stays cleaner then any US pipe I've seen. Only bad buildup area is on top at the cap.

We have a huge wood furnace and since it also heats our hot water, I run it turned down way low and smoldering when the outside temps get up in the 40s. Chimney still stays fairly clean.

Funny thing is we tried to buy a Canadian built EPA woodfurnace. "EPA Caddy." At the time, it was the only EPA tested woodfurnace in the world. But, the factory in Québec refused to sell it to me here in NY. I begged them and told them I'd buy with a voided warranty, but they said "no." And gee, my family is French. Oh well.

As usual, JD Maris has it right. Your triplewall
pipe works on the principle of cooling the smoke
so the heat doesn't reach combustables in your
house. This causes the creoste to condense on the inside wall of the pipe and cause a buildup like you have. JD's double wall insulated works on the principle of keeping the heat contained inside the pipe which keeps the smoke hot and it doesn't condense until it reaches that cold cap on the top of the chimney. What to do about it?
When you load your furnace, let it burn real hot for a few minutes after you load it before you damper it down. Get some of those creosote prventing logs others have mentioned. Get rid of that triple wall pipe and replace it with double wall as soon as you can afford it. I've seen double wall go cheap at auctions.
It will do no good to put insulation around or enclose the triple wall pipe because it takes cold air down from the top of the chimney thru the outside space and brings it back up thru the inside space to cool the smoke.
I've heard about the salt in the firebox and also putting all your potato peelings in to
maybe it works maybe it doesn't.

Agree with all posts. You didn't state whether your chimney was straight up or had elboes. I use ONLY straight up and the eight feet going through the ceiling and roof are double wall , stainless inside and insulated with 2" of spun ceramic. I don't "cook charcoal" like you are but I have never had to physically clean it at all. Burn it hot every time I fire it up or once a day. There's just nothing left in it to clean. Paid $250 back in 1990 and never been happier. Also will never have anything but "straight up"!