New Jotul Oslo - Smokey out of Stack

[MrKenmore]

Hi everyone. I would like some feedback on my new Oslo. The setup is simple. About 5.5 feet of 6 inch single wall pipe (with two 45 elbows) transitioning to 8 inch single wall for 1 foot and then 8 feet of 8 inch class A double wall insulated chimney. I can get the stove going to 350 degrees no problem. My problem is there is smoke out of the stack. I thought I would be getting away from that with the Oslo. I can reduce the smoke if I get it up to 500+ degrees with the intake wide open. But for long burns with the air intake nearly closed, I get smoke out of the stack. Is this my wood? Too green. I am using some oak and black birch split in early spring. Or do I need to get the stove up to VERY high temps to maintain the slow burn. I am not seeing the extended burn times and am getting a lot of smoke when I do.

Thanks.

 

[Corey]

Could be several things going on. Adding up all your flue lengths, I only see about 14 feet assuming everything is straight. But you also mention the two 45 elbows so I get the feeling you are definitely on the shorter end of the flue lengths and lower end of the draft scale (I am too!) It may be hard to get a good draft going, especially in slightly warmer weather or if the air is not wide open

Depending on your location and when the wood was cut, it may be a bit green still. Although I seem to see more of a difference based on when the wood was cut versus when it was split. Do you hear any hissing and/or see any foam from the ends when it is burned? Also, depending on where your thermometer is...I think 500F at the top, center of the firebox is considered a "good" burn. 350 definitely seems to be on the cooler end of the scale. Also, what size of wood are you using for your long burns. Ideally, a few big, thick piecs thrown on top of a good bed of coals will burn the longest. If you are trying to use several small splits for a long burn, that may not work out too well.

Corey

 

[MrKenmore]

There is no foaming but there is occasionally some hissing. I am going to go grab a load from the in laws that I know is completely dry to see if my smoke goes away. My goal is slow burning, high heat, long burns and no smoke. I think my draft is decent. Whats the best minimum height chimney for draft?

Thanks everyone!!

 

[MountainStoveGuy]

not to mention the 8" stack, that compounds the 14' minimum chimney. Your not getting enough draw. 2 45* = 1 90* and that will deduct from the performance as well. 350 is too cool. These stoves need too be run full blast untill you get the hang of them, thats all stoves, not just jotuls. I hear Oak need alot longer to cure. I dont burn it so i will let someone else comment on the wood quality. Wood quality aside, you will not get great draft on that chimney, no matter what the circumstances of the wood are.

 

[MountainStoveGuy]

There is no foaming but there is occasionally some hissing. I am going to go grab a load from the in laws that I know is completely dry to see if my smoke goes away. My goal is slow burning, high heat, long burns and no smoke. I think my draft is decent. Whats the best minimum height chimney for draft?

Thanks everyone!!

14' of strait 6" pipe is the minimum. Your draft isnt decent, and your wood is most likely not seasoned enough. Secondary burn stoves are not slow burners, so trying to get slow burning, high heat, and no smoke isnt realy a option untill you have a very very hot coal bed and a few fresh splits. Its just not the way these stoves are designed to run.

 

[MrKenmore]

OK. Thanks for the tips. I really appreciate it. I am just trying to get used to the way the Oslo operates and how to get the most out of it. What's done to increase draft in this type of situation? More class A chimney pipe? That would be quite a bit taller than my roof existing line.

 

[webbie]

Also remember that steam looks like smoke, so make certain you look closely - smoke is usually more brown or black, while pure white can be a lot of steam. Long burns always take some technique - like having a big bed of coal, loading and then running hot for 20 minutes to dry out the wood, then turning it down...etc.

 

[MrKenmore]

OK. It's definitely not brown or black. Right now I have the Oslo cooking at about 425 (EDIT 460 right now) degrees with the air intake at about 60%. The chimney is perfectly clear - no smoke, no steam. I think I may have been setting the air intake incorrectly. Is my poor draft requiring the intake to be open more in order to reach the high temps? This will cost me more wood correct?

REVISED Measurements-My total height of the stove pipe / chimney is more like 7 feet of single wall on the inside and 3 feet of class A in the attic space and 5 feet above the roof line. Thats a total 15 feet. Granted 9 feet of that is 8 inch which is not preferable.

 

[MountainStoveGuy]

that is correct, the lack of draft will not let you turn the stove down as much as you would with super draft, but even with super draft you dont get 12 hour burn times. That oslo should be getting 6-8 hours of clean burning operation. You should have some coals after that, but not much. Seconday burn stoves dont simmer, simmering a stove defeats the purpose of these new efficient stoves. It takes heat and a lot of it to use the flue gas a fuel, you waste alot of that fuel up the chimney when you make a cool, smouldeing fire. Your oslo should be at least in the 500* range for optimal effeciency, 550*-600* doenst hurt a bit.

Now here is the kicker. If you add to much 8" pipe you will overdraft the stove, but adding alittle at a time will be best, untill you get the draft your looking for. If you can get 6-8 hour burn times with clean burning, then your draft is fine. Just adjust you burning habits.

 

[MrKenmore]

OK. Thanks very much for the education. Very helpful. It all makes more sense now. I guess I had the wrong (old school) mentality on burn times and air intake. So the bottom line is I need to run the stove above 450 minimum for best operation and it may require more wood to maintain that temp. Also look into going to a taller (maybe 6 inch) stack.

 

[MountainStoveGuy]

your welcome, glad i could help

you chimney would be fantastic if it were all 6". you would have faster start times and you would have more control. You will probably be fine on the 8" if the start ups arent to hard. The other common issue with 8" pipe is the wind, it tends to reverse the chimney. If start ups, and windy days are tolerable, then dont go to the expense of messing with the chimney, if they drive you crazy, dont waste your money on any more 8" pipe, either reline what you have to 6" or start from scratch next summer.
The absolute best bang for the buck at this moment would be for you to go to interior double wall black. It will keep the chimney hotter for better draft, and help with the heat loss through those 45* elbows. If it were my stove, that would be the first thing i would change.

 

[MrKenmore]

Funny you mention the double wall interior.......that was my original idea. But I wanted to save a few bucks and reuse the old Class A 8 inch. No manufacturer would mate double wall interior to single wall interior or another manufacturer's class A. Penny wise pound foolish! What I'll probably do is watch the classifieds for someone who is selling a complete 6 inch pipe setup.

 

[MountainStoveGuy]

you can mate differnt brands of double wall and class A, just not single wall and double wall. There is absoluty no problem saving pennies if it works. Give it a chance, and burn it no less then 50% open with wood that you know is seasoned. If you get the described burn times and no smoke when the wind is 100 mph you should be in good shape.

 

[MikeS]

FYI, I got Jotul model series 8 with catalyst on 13.5 feet of 6" (5.5 feet double wall black and 8' of class A).

Draft is OK, but not fierce. It is difficult to operate anywehre below 1/2 on the silly little slider for air intake.

Startup takes some skill and timing--it drafts right away and is easy to light, but you have to work it and get it somewhat raging before clamping down the door.

And then you have to watch it a while to see where it settles down before trying the catalyst.

Once running on the cat, it is ok for long burn (up to 5 hours burning aspen, which I suspect has pretty poor energy yield).

But if I try throttling the intake air, I can get unhappy surprise of smoke on the wrong side of the unit after the fire dies down.

I will be running wide open over the next weeks, I think, until i get better at operating.

Shifting wind or other anomoly could have caused tonights smokey room, too. I didn't like that.