Jotul Oslo Secondary Burn

[lydiatwin]

We have a new Oslo and have been experimenting with burning technique for about a month. Our wood seems to be dry hardwood (no pop and sizzle or seepage at the ends of the split). Draft is good. No problems getting it started or having coals in the morning. Measuring the stove top temperature in the corner. We don't have access to the stove pipe.

However, we don't seem to be getting secondary burn or maintaining steady temps. Starting from a cold stove, I'll fill the stove loosely maybe half full and starting with the loading door ajar and full primary air run it up to say 400 degrees. Then I'll load it full and keeping the primary full open go to 500 or 550. This could take from 1 to 2+ hrs, seemingly dependent on how much ash is in the stove. Now I'll ease the primary back in increments but right away I start to lose temperature. Within a half hour it could be down to 450 and I don't see the expected "light show".

In order to keep the temp in the 400+ range I have to run the primary air vent at 50% or more. We're burning through wood at a great rate. A full stove can be down to charcoal in 3 hrs and have just briefly peaked at 500 and struggled to stay above 400 during that time.

Why no secondary burn, or am I missing it? I realize I probably can't damp the primary all the way shut, but shouldn't I be able to maintain the temp for a couple hours or more at say 75% closed?

Thanks for your suggestions.

 

[oldspark]

Probably the wood, get some known dry wood and try that.

 

[fortydegnorth]

I'd definitely say wood. You should see the higher temps much sooner in the burn after reload and secondaries should least a couple hours easily with dry wood and the air choked all the way down.

 

[Shari]

We have a new Oslo and have been experimenting with burning technique for about a month. Our wood seems to be dry hardwood (no pop and sizzle or seepage at the ends of the split). Draft is good. No problems getting it started or having coals in the morning. Measuring the stove top temperature in the corner. We don't have access to the stove pipe.

However, we don't seem to be getting secondary burn or maintaining steady temps. Starting from a cold stove, I'll fill the stove loosely maybe half full and starting with the loading door ajar and full primary air run it up to say 400 degrees. Then I'll load it full and keeping the primary full open go to 500 or 550. This could take from 1 to 2+ hrs, seemingly dependent on how much ash is in the stove. Now I'll ease the primary back in increments but right away I start to lose temperature. Within a half hour it could be down to 450 and I don't see the expected "light show".

In order to keep the temp in the 400+ range I have to run the primary air vent at 50% or more. We're burning through wood at a great rate. A full stove can be down to charcoal in 3 hrs and have just briefly peaked at 500 and struggled to stay above 400 during that time.

Why no secondary burn, or am I missing it? I realize I probably can't damp the primary all the way shut, but shouldn't I be able to maintain the temp for a couple hours or more at say 75% closed?

Thanks for your suggestions.

Whoa! There is no reason to keep the door open IF you wood is well seasoned.


Your wood is NOT well seasoned.


Get a moisture meter - resplit a split - and get back to us on the reading.

 

[gibson]

I think there is a "sticky" on the forums home page for this. If you are sure that your wood is dry, the next culprit would be the chimney. I think the Oslo likes at least 15' of chimney. Is it lined?

 

[nelraq]

Once you get up to 400 and you "load it full", turn the primary down to about 3/4, then to 1/2 etc. The stove door should have been closed around 350.

By leaving the primary on all the way after you "load it full", most of the heat is going up the chimney - not heating the stove!! No wonder it takes 1 - 2 hours to get it up to 550!

The firing method outlined above will help as long as: 1) your wood is well seasoned and 2) your chimney has adequate draft.

Hope this helps. You will love the Oslo once all the little kinks are worked out.

 

[Shari]

Once you get up to 400 and you "load it full", turn the primary down to about 3/4, then to 1/2 etc. The stove door should have been closed around 350.By leaving the primary on all the way after you "load it full", most of the heat is going up the chimney - not heating the stove!! No wonder it takes 1 - 2 hours to get it up to 550!

The firing method outlined above will help as long as: 1) your wood is well seasoned and 2) your chimney has adequate draft.

Hope this helps. You will love the Oslo once all the little kinks are worked out.

Where are you getting this 'close the door at 350'?

I start a cold stove two different ways:

1. Toss in some kindling & a fire starter, light the fire, close the door. Add more wood after kindling is ripping. Close the door immediately after adding more wood.

or,

2. Fill the stove, do a 'top down' stove light, close the door.

Either way, the door is closed almost immediately with full air. Stove comes up to temp within 1/2 hr.+ and then close the air to 1/2, wait about 15 minutes, turn stove down to 1/4.

 

[ansehnlich1]

Probably unseasoned wood. I'm burning Oak that's been split and stacked for 3 years.

Also, sounds like you're burning most of your load down before you even shut the door.

You should be able to close that side door at somewhere between 200 and 300 degrees and with the primary air full open shortly after that have secondaries.

 

[ansehnlich1]

I'd like to see some pics of your setup.

What type chimney do you have. If you have an exterior masonry chimney that is terra cotta lined that has a DRAMATIC negative effect on the Oslo's burning characteristics.

Reason I know is I have one

When I lined my chimney, and insulated it, the Oslo performed completely different, of course, assuming dry wood.

Me....Jotul Oslo, 22 ft. high 6 inch stainless lined/insulated exterior 2ft x 2ft brick chimney, oak split/stacked 3 years ago, PRICELESS

 

[lydiatwin]

Thanks for the input!! Here are some answers.

Side door: I've been reading a lot on this site and doing trial and error. The fire doesn't want to get started with just the primary air open. I can close it probably at 250, but then it takes longer to get up to 400+.

Chimney: We have a 6" Metalbestos chimney. The paperwork says 21'. It runs through a framed box up to the ceiling then out. Guessing there's at least 8' above the roof line. Draft seems fine.

Primary air: I agree that all our heat is going up the chimney. Problem is without the primary air open full, we can't get up to 400+. As soon as I damp the primary even to 1/2, the temps start dropping. My understanding is no secondary burn unless the temps are 400+.

Wood: We didn't get/stack the wood until Thanksgiving. It's a new stove not operational until mid December. The guy said it was seasoned (cut 3 years). Who knows. The bark is off most of it and some of it looks greyish. Not experienced enough to be able to heft one and estimate the water density. Will investigate a moisture meter (who knew such a thing existed - want to volunteer where to find one?). Meanwhile, my working theory, as most of you have pointed out, is wet wood.

This time of year our options for getting more wood are severely limited. Going to go get some Eco-brick today and experiment with that. Might be able to mooch some known dry wood from a friend.

 

[PapaDave]

lydiatwin,
First, welcome to the Hearth!
As the others have pointed out, it's the wood.
"Cut 3 years" doesn't always mean it's been split and stacked that long.
I guess in all your reading, you focused more on everything BUT the wood.
Not trying to be mean, it's just that most of us have been in your shoes. It's the wood.
Lots of folks here have gotten their moisture meters from Harbor Freight, and say that they work well, and are inexpensive (15-20 bucks).
When/if you get one, resplit a couple of your splits of wood, then take a reading from the fresh face of one of those pieces. I'd be surprised if the wood is even down to 20%.
nelraq made the point on your 1-2 hours with the door open comment. With the door open that long, the wood will burn down fast.
I did a lot of the same things you're doing the first 2 years. What a struggle to get DRY wood. Nobody around here burns dry wood. It's all c/s/d, about 1-2 months before it's burned, and sometimes less.
Good luck, and let us know how things work out. TONS of experience and knowledge here.
Oh, and pics are well liked. Sometimes just for the drool factor, but they can be useful to help folks help you too.

 

[oldspark]

The Eco-Bricks should tell you what you want to know, they burn hot so go easy with them and you can mix some or your wood with them.
Welcome to the forum and just remember we do not bite (only a few any way)

 

[ansehnlich1]

Hey make sure your chimeny cap/screen isn't clogged.

 

[lydiatwin]

Saturday was a busy wood related day. Bought a moisture meter, and after much searching, bought some bio-bricks. Was a bit of an ordeal splitting a split - let's just say we don't process our own wood and swinging a maul isn't a regular activity. At any rate, we confirmed that our wood isn't seasoned. The meter tops out at 28% and that's what it was reading. Was just a sample of one. I'll try another split for verification.

The bio-bricks have certainly reduced our getting up to temp time. I'm also closing the side door as soon as the start up fire will sustain itself (could be as low as 150 - 200). Once things are going, I've been putting in two bricks then filling with wood. Still not getting the burn times I'd expect. The temps are still dropping as soon as the primary air is reduced. Going to experiment with less wood more bio-brick. Have heard over and over to use the bio-brick sparingly because it burns so hot, but that hasn't really been our experience.

We also brought more wood into the basement and are stacking more near the stove. Don't have a wood rack yet and space is limited. Not sure if having wood inside a couple of days will help, but it can't hurt. Am also researching getting some seasoned wood yet this year. Seems a waste to "burn" the green stuff we've got stacked.

Yesterday as things were dying down and the stove top temp was 375 we SAW THE SECONDARY BURN! This was clearly coming out the secondary tubes. Have seen other bluish flames dancing on the top of the logs, but this was the first that I was certain it was secondary burn.

Thanks all for the recommendations. We still have some learning to figure out how to operate this stove effectively.

 

[PapaDave]

Shari, did you make that shirt? :lol: Love it. I could have used one when I first started, but I figured it out pretty quick without it.
Every new wood burner should be given one when they sign in.

 

[Shari]

Shari, did you make that shirt? :lol: Love it. I could have used one when I first started, but I figured it out pretty quick without it.
Every new wood burner should be given one when they sign in.

You mean this one:

Yes, I did make it. I kind of got tired of trying to tell new burners "It's the wood!" so I though a "visual" might get through a little better than just words....

 

[woodsmaster]

Everyone who buys wood should have one of those shirts on when they have wood delivered!!

 

[lydiatwin]

We continue to experiment and have been pouring over the multitude of posts here. This thread was particularly interesting. https://www.hearth.com/econtent/index.php/forums/viewthread/64896/

We bought a pallet of bioBrick and have been burning them almost exclusively. We are still not getting the kind of results that others have reported. This morning, with a mostly cold stove (there were some coals from the night before), we put in 13 bioBricks and two smallish spilts of wood. Left the side door open for 5 minutes until things got going. Kept the primary air open until the stove reached 550 - 600. That took about an hour. Closed the primary down 7/8 shut in gradual steps over 5 - 10 minutes. At this point we're clearly seeing secondary burn. The temps stayed at 550 for maybe 10 minutes. Within an hour after first reaching 550, the temp was down to 400, very little fire was visible in the stove. The stove seems to be filled with glowing charcoal-like bioBrick. It'll stay at 400 for another half hour or so, but then drops closer to 300. I don't think we should have to be reloading every hour or two, and running at 400 or less doesn't seem good either.

We've been quite disappointed because the stove isn't heating our space. We are approx 2000 sqft - depending how you count (attic or unheated basement). The floorplan is open and we have a wall of glass running the entire width of the south side of the main floor.

Given that we've eliminated wet wood as our problem, I'm starting to wonder about the draft. I'm including photos of our set up. The chimney is 6" Selkirk Metalbestos UltraTemp. The invoice says 21' total. It's a little hard to see, but I'm estimating the middle section of exterior pipe is 4 foot. We have cathedral ceilings. I don't know how much chimney runs through the interior, but it's like two stories high. The chimney runs through a previously existing 8" factory fireplace. That's just sitting inside a drywall framed box. I doubt there's insulation in the interior box.

One other variable that I hardly ever see discussed is the amount of ash in the stove. We've been experimenting here too. This morning we emptied the ash pan for the first time in a week. We didn't clean the ash out of the stove. We have seen that the stove comes up to temp faster when there's more ash in the stove and ash pan.

I feel that this might be too much information. To summarize: we're burning bioBrick and still not able to maintain stovetop temps of 400+ for more than an hour.

 

[schortie]

It sounds like you have a fair amount of space to heat - with the high ceilings and wall of windows. How warm is the house after a couple hours of running the stove like you posted? Are you still cold after a few hours?

I start to shut my f600 down at about 350 or 400 - to almost half. It continues to climb to 500 or so by the time I get to the last air adjustment. If I let it rip to 550 or 600 before I started to shut down, the load certainly wouldn't last as long, and a lot of btu's would be up the chimney.

Plus, if I'm adding up your heat time (much different than burn time), you have two or three hours of over 400, with most of that time around 500. I don't see temps like that last more than a few hours on my stove on less than a full load.

I haven't used biobricks, but I can't imagine they pack the btu's of oak - but I was wrong once before.

 

[lydiatwin]

We do have a challenging space to heat. Overall the house has been pretty chilly (maybe 62 in spots) since I'm barely running the furnace. Near the stove it can get to 70, but more likely 68.

My partner and I have been debating how long to let it rip before damping down. If we go to 1/2 throttle at 400, it won't get much above 400. I agree that waiting until 500+ is blowing lots of our fuel out the chimney. We're concerned about creosote build up if we run most of the time below 400. I wouldn't say we've been able to run 2+ hrs at 500, more like one hour at 500. Using your terms, it feels like we're only getting heat time of about an hour, (max of 1.5, with 1/2 hr leading up to full temp), out of a fuel load.

We went to BioBrick after discovering our wood wasn't adequately seasoned. It's compressed hardwood scrap/sawdust and based on other postings, everyone says they burn really hot. At first I was afraid to load up the stove with them, but it doesn't seem to matter how many we stuff in.

 

[toddh]

I am burning one year old seasoned wood and I can get to 600F in about an hour from a cold stove. I start to turn the stove down at 450-500 and it will jump another 100 degrees before leveling off. I would say I reload every 3-4 hours usually when the stove gets down to 300 F. Get good wood for next year and you will see a huge difference. I am heating 2700 sq feet from the basement and I can hold my house at 70f. I have 20 foot ceiling on the main floor.

 

[lydiatwin]

ToddH, we're getting nothing like those results. The BioBrick should be equivalent (or better?) than one year seasoned wood, right? Thanks for another data point. We're still trying to figure out what to expect.

 

[Ubookz]

Greetings! just reading about secondary flames, I have a P.E. but I am thinking-could it be a inlet air draft problem? if you have seen a simple "rocket" stove- they burn clean and hot because of the fast air draft? maybe an o.a.k will help?

 

[Wade A.]

Not to stir the pot on the seasoned wood question, but a new burner might need to know that "Shari's Law" , like most laws, comes with exceptions and caveats. It is also subject to geographic climate variables and conditions. Here in the deep South I can easily buck a green oak (red, white, river, you name it...), split and stack it in April and I can have low single digit interior moisture content by mid October, just in time for our heating season. Unless you are planning on making furniture out of it, that is plenty seasoned in my book. The keys are splitting it small, getting it off the ground and under cover as quick as possible, stacking it with a southern exposure and plenty of opportunity for the wind to reach it. Granted, Lydiatwin doesn't have the long baking months of southern heat to work with, but there are ways to accelerate the process.

That said, I certainly agree that the wood is the problem here. 28%?! Shoot. Put that in a bucket of water and it is likely to sprout!

 

[Hanko]

Shari, did you make that shirt? :lol: Love it. I could have used one when I first started, but I figured it out pretty quick without it.
Every new wood burner should be given one when they sign in.

You mean this one:

Yes, I did make it. I kind of got tired of trying to tell new burners "It's the wood!" so I though a "visual" might get through a little better than just words....

Hi Shari. hope you had a good summer.