wood stove creosote buildup questions

[ken morgan]

After last week, my flame suit is on and I have donned my mythical armour please feel free to offer advice and comments.

So I am finishing the install on a single stage (no reburn) cast iron mini stove in my vacation cabin. No, building codes exist yet for wood burning stoves in my area. there are not a lot of wood burners (per capita) in japan so the government is behind the power curve on creating laws that apply.

I used stainless steel double walled flue pipeing from the stove out through the roof with a short double 90 as it exits the stove 90 out then 90 up with 150mm (3") of pipe between 90's for a total horizontal run of 180mm (6" approx) then a 6 meter run straight up. I used japanese 12mm (1/2" ) fireboard (900 c rated) mounted to 1' steel standoff spacers between the double walled flue and any combustible surfaces and at its closest the fireboard has 250mm (10") of clearance to the double walled flue. flue extends to 400mm (15") above the roof line.

(any issues that anyone can see so far?)

My primary question is creosote buildup. how do you gauge build up, I realize that any and all are bad.....but at what point should I freak out? I will be burning a lot of Japanese pine initially, and as such plan on cleaning the flue once per month for the first season. usage will be roughly 8 days per month (weekend trips to cabin).

I have not yet installed smoke detectors, but I do have Carbon Monoxide detectors scattered through the house as Japanese law requires them for any gas/oil/wood/any fuel) burning appliance.

so what am I looking at in so far as dangerous levels of buildup in the flue? anybody got any photos to share with a beginner that show different levels of flue buildup?

I am searching google as we type this but would prefer feedback from users directly.

thanks for your assistance in this matter.

Ken Morgan

 

[zogger]

If you burn hot fires with dry wood it shouldn't be bad. I personally don't use an exhaust damper, I found out that was the easiest way to eliminate creosote buildup.

 

[IyaMan]

Thats sounds like a long run of chimney pipe, about 9 meters /30ft total ? (its hard to calculate, the measurements were a bit confusing) Creosote builds up when the smoke/exhaust cools, which would happen when the pipe is long, though the double-wall will give an insulated effect.

When you say Japanese pine, do you mean sugi (cedar), hinoki (cyprus) or matsu (true pine, can be red pine or black) or something else ? All have distinctly different burn qualities, though Japan is so humid that you'll be unlikely to get it as dry as in the US or elsewhere, so it will seem a bit smokey even when dried for 2 years. Sugi burns quicker, lights easily, and leaves behind a decent amount of ash. You'll burn a lot of sugi compared to practically any other wood, though its also super plentiful, so I guess there's a trade off. Hinoki is the best of the bunch, and burns hotter, longer, but isn't as good as sugi for kindling. Its also a bit expensive and not necessarily considered a "fire wood" by most people, but I prefer the way it burns over sugi and I have it fairly available. But avoid matsu if at all possible for a wood stove. Its got lots of resin/oil and if you don't gum up your saw or your hands while processing it, it will be the one to lead to the most creosote build up as it gives off quite a bit of smoke from the resin.

The best way to gauge creosote build up (and with a long pipe that has any sizable near-horizontal run, you will surely have it) is to become familiar with your usual burn rate and/or fire intensity. A clogging pipe will begin to act like a damper and prevent a good burn, and will especially be noticable when starting the fire (the smoke will fill the stove, and not immediately go up the chimney). I've come to learn that on my current stove set-up I can go about 10-12 weeks of daily use before any build-up affects the burn all that much (I have a 2.5 meter vertical pipe, with another 3 meter run at 45 degrees, followed by a final 1.5 meters out the roof, but its mostly single walled 12 cm pipe). And since the cooling of the exhaust smoke is what affects the build-up, you may notice that different times of year will also change this (so you may get more build up in January as opposed to April). But I've come to notice (at least for me) that when the build up begins, it will get thick to a point of being a problem within about a week to 10 days, so when it happens, it does so relatively fast. So be sure to have a chimney scrubber ready and know how to clean your system.

 

[TimberWolf530]

If you have the right sized flue, burn seasoned wood, and keep your fires burning at the proper temperature, you shouldn't build up any, or at least very little creosote. If you are only burning 8 days a month, and plan to clean your flue once a month, unless you just like to climb up on your roof, cleaning it that often is overkill. I start burning in October as needed, and constanstantly from early December up through March. If I have a warm day at some point in the middle of winter, I will shut it down, and clean the flue. Otherwise, just at the end of the season. I never have any probelms with creosote. I agree with not using the exhaust damper. A hot flue is the engine that drives your stove.

 

[IyaMan]

A hot flue is the engine that drives your stove.

True, but keeping a hot flue also depends on what you burn and how often. You mentioned this is a vacation cabin, so a 24/7 constant burn probably won't be the case, so from time to time the chimney will cool completely, and that will create build up. Also, if burning only softwood, you may have variances with the temperature output, and maintaining a constant 24hr burn for even when you are there may be difficult without hardwood. And this being Japan, and so prone to earthquakes, depending on how confident you feel your set up is, you may not want to burn 24hrs non-stop during whatever hours of the day you're not there and/or asleep due to the possibility of an epi-center being under your house.

But I'll agree, climbing up to the roof in the snow to clean a flue isn't the way to spend the day, but with my conditions and the wood I use, its usually necessary once per year in the mid-winter.

 

[ken morgan]

Thats sounds like a long run of chimney pipe, about 9 meters /30ft total ?

When you say Japanese pine, do you mean sugi (cedar), hinoki (cyprus) or matsu
. But avoid matsu if at all possible for a wood stove. Its got lots of resin/oil and if you don't gum up your saw or your hands while processing it, it will be the one to lead to the most creosote build up as it gives off quite a bit of smoke from the resin.

sorry about the poor explanation on the dimensions. total length will be a little less than 6 meters including bends. The stove is one of those cast iron Honma stoves like they sell at homes, D2 or cainz homes etc. (I know small and cheap) got it for free so the price was right. look at the drawing to understand a little bit better. I needed that length to get it up and out of the house and above the roof line. the actual horizontal run is only about 8" 200 mm give or take. just enough to get it into the recess for the flue/chimney while keeping the stove itself out in the open. the flue pie runs up an insulated space into the overhead of the house and then exits roughly in the middle of the slope. so about 4 meters of it is in the house till it exits the roof then about 1.5ish to the weird ass "H" splitter the Japanese use at the top which puts it at roughly 30cm above the roof line

Matsu initially, (about 1 cord's worth) then mixed for the next 4 cords of various smaller stuff. When I cleared my property there was a lot of it so it had to be cut to make room for the garage. I have since joined a woodcutters club and cut about 2 cords of oak, but it will be a year before it is ready to burn as it is still drying.

ken

 

[ken morgan]

If you have the right sized flue, burn seasoned wood, and keep your fires burning at the proper temperature, you shouldn't build up any, or at least very little creosote. If you are only burning 8 days a month, and plan to clean your flue once a month, unless you just like to climb up on your roof, cleaning it that often is overkill. I start burning in October as needed, and constanstantly from early December up through March. If I have a warm day at some point in the middle of winter, I will shut it down, and clean the flue. Otherwise, just at the end of the season. I never have any probelms with creosote. I agree with not using the exhaust damper. A hot flue is the engine that drives your stove.

central Indiana? what part? I am from south west Indiana originally in Sullivan county on the IN/Ill border on the Wabash.

 

[ken morgan]

yes its the whole matsu (japanese pine) thing that has me worried. the whole install is new the pipes run up an insulated space till they exit the roof so other than the 8" short dogleg it is straight up and all but the last 5' are within the house so it will stay warm. The double 90's are both right at the stove, so the gasses will still be nice and hot. but Matsu is a nasty creosote laden wood from what I hear and that is what worries me. plan is to only burn when we are physically there anyway as the house has dual toyu heaters than feed from a large central tank. the idea was to fire the woodstove up but leave the heaters at their lowest automatic settings so that when the fire dies out at 0200 or 0330 the toyu heaters will pick up the slack and keep the house warm.

 

[IyaMan]

the idea was to fire the woodstove up but leave the heaters at their lowest automatic settings so that when the fire dies out at 0200 or 0330 the toyu heaters will pick up the slack and keep the house warm.

Looks like a pretty straight shot chimney, so it'll probably be fine. And should be easy enough to clean if need be, just take notice in your fire intensity and if smoke is filling the stove when lighting. Yeah, matsu kinda stinks as a firewood, but if thats all you got, what can you do. Have you burned any yet? You may want to try some out, see if it stinks up the house, if it burns well enough, and find out how long you can go without needing to re-fill the stove.

Most Japanese don't run toyu heaters at night when asleep or unattended due to earthquakes and/or due to the exhaust (especially if using older style heaters or those without exhaust vents to the outside), but if the toyu is fed from a central tank to the both of them, you must have a pretty decent system installed that can operate over-night.

 

[IyaMan]

... to the weird ass "H" splitter the Japanese use at the top which puts it at roughly 30cm above the roof line

You get much snow? I've had storms that would easily bury that.

 

[ken morgan]

You get much snow? I've had storms that would easily bury that.

its fairly dry around fuji, so even though its cold as fark most the times the snow is not that deep, plus the angle of the dangle on the roof would allow about 2 meters of snow on the roof without covering it. long before then I would be clearing it just for gp

 

[ken morgan]

yeah our toyu heaters have external vents and a central fuel tank so no worries, we used it all last winter with no issues.

Oh an auto shutoff on earthquakes

 

[TimberWolf530]

central Indiana? what part? I am from south west Indiana originally in Sullivan county on the IN/Ill border on the Wabash.

Hamilton County in Carmel. Not many of us wood burners here in Carmel. I've fished Lake Sullivan several times. Nice little lake. How did you end up in Japan?

 

[ChoppyChoppy]

Huh funny, here Matsu is a borough. Short for Matanuska-Susistna.

Toyo stove very common here too.

As far as earthquakes... yup, plenty here (most in North America). If an earthquake upset a wood stove, the house would pretty well be demolished anyhow. I suppose a person could attach it to the floor.

As far as your piping, if you can do 2 45s instead of the 90 it'd be better for draft and a bit less buildup of cresote.

 

[ken morgan]

Hamilton County in Carmel. Not many of us wood burners here in Carmel. I've fished Lake Sullivan several times. Nice little lake. How did you end up in Japan?

Former Marine, did my time and now work as a contractor on the local US navy base. We bought a house close to it but its the middle of the city, so I took some savings I had and bought a vacation home on the flanks of Mt. Fuji. hence woodburners, chainsaws etc. etc. I can't believe as depressed as the economy has been in Indiana that there are not more wood burners. as a kid we had a wood burner and I split a lot of cords by hand and cut it all with a little 14" chain saw from the mid 70's

 

[ken morgan]

Huh funny, here Matsu is a borough. Short for Matanuska-Susistna.

Toyo stove very common here too.

As far as earthquakes... yup, plenty here (most in North America). If an earthquake upset a wood stove, the house would pretty well be demolished anyhow. I suppose a person could attach it to the floor.

As far as your piping, if you can do 2 45s instead of the 90 it'd be better for draft and a bit less buildup of cresote.

wish I could run 2 45's but the space for the pipeing is kind of limited due to the way the house is built, I would have to knock out a wall and I have no intentions of going that far. good thing is the 90 that goes from horizontal to vertical has a knockout bottom so its real easy to run a cleaning brush from the top to the bottom. just remove the knockout drop the spring a ma bob (don't know what to call it ) down the chimney pipe and pull it out the bottom. run it through a couple of times should do the trick. My problem is how often to do it, from what I just read online it looks like anything approaching 1/8" is cleaning time, so I will have to burn some and watch it over the first couple of seasons till I get it figured out. I figure a decent shop vac and some careful planning should make it easy to do.

They do not have chimney sweeps as a profession per se, as there are not enough wood stoves. the guys that do it are just regular joes with a ladder a truck and a bristle brush on a flexible lead (looks like a snake for the sewer with a brush on the end). not like in the states where you have regs and training and whatnot.

my plan is to retire up here to the cabin in about 10~15 years after the girls graduate high school and have moved on to colledge, rent out the current house and just play grizzly adams till I pass on.

 

[ken morgan]

How many members we got in japan anyway? seems like we need to have a GTG I owuld not mind traveling a bit to meet some of the other members. It seems to me to be one of the things we all miss out on being overseas.

 

[ChoppyChoppy]

I've been to Yakota once. The wrong side driving made my head hurt!

 

[IyaMan]

I owuld not mind traveling a bit to meet some of the other members.

Kanto area is a 10hr drive from me.... via hiway, with $120 in tolls

 

[WoodTick007]

You've installed the best vent pipe that is on the market or available for venting solid fuel Heating devices. As long as your firewood is relatively dry you should be perfectly fine and have no concerns whatsoever. Pine Burns Excellent and puts off wonderful Heat. It's drawback is that and has poor calling qualities like Oak or Rock maple or Ash.