This is my second season with my Jotul Oslo, and 14th year burning wood as our primary heat source (I also have a Clayton wood furnace). How long should I get a good secondary burn with my Oslo? I always get my stove up to about 500 degrees surface temp, then shut the air to halfway for 5-10 min, then three-quarters of the way down for 5-10 min, then almost all the way down. I always get a good secondary burn, but it seems like they only last for about 2 hours, then I don't see them anymore, and the stove temp cools down to the 250-350 range for the next 5-6 hours. I always have coals left 8-9 hours later. Right now I am burning a mixture of ash, oak, and walnut. Thoughts? Should I let it get up closer to 550-600 before shutting it down, or should I shut it down sooner (like 450)? Should I leave my air at 3/4 of the way shut down instead of almost all the way? Just trying to maximize my burn times....even if you don't have an Oslo I would appreciate your thoughts.
First let me say that I wouldn't be so bold as to tell you how to run yer stove since that was I didn't like about another site I usta read. I assume you are talking about starting from a relatively cool stove after 8 to 9 hours. With my Oslo on a cool start (this is in the morning about 12 hours after the last load) I put 2 medium splits front and back of the box loaded E.W. I always have a good pile of hot coals so I just put some small dry kindling on them and have a cup of coffee. The kindling always takes off on its own and then I add some bigger kindling and larger splits on that. Let it get going good with the side door cracked as needed. Depending on outside temps and wind determines how long I leave the door cracked. Close the door when needed and let it go till my flue temps start to rise. With my somewhat primitive chimney set up, when the flue temps get into the 350° to 400° range that usually means the stove top is around the same temp. That's when I shut down to about half. The stove temp will climb and then I shut it down to a quarter an eighth air. After awhile I'm running about 500° ST temp. That temp is my sweet spot as far as heat to wood ratio. There really is no time frame to this as there are to many variables involved such as wood, wind, outside temps so on and so on. As far as secondary's go, 2 hours is as good as I can get depending on what folks call secondary's. I very seldom get the 3 tube gas grill effect. Maybe the rear tube and those blue floating flames or the all out gates of hell melt the glass kinda thing. I don't strive for long secondary's like some seem to get because I have found that in my set up the stove itself stays hot longer when I have some flames offn the wood too. That means more useable heat to me. If I can wake up in the morning 12 hours after the last load and ole Black Sabbath still has a ST temp of 200° that means it is still giving me some if not much useable heat. I mean think about it. If you have a 550 pound hunk of cast iron sitting in the middle of the hooch that is 200° is it not giving off some heat? This is all clear as mud right? But just my thoughts. Don't let yer stove get that hot before turning down the air a couple of times. Do this when outside conditions are different to get a feel for how the stove reacts under certain conditions. Trust me, we can get a super draft situation here and there have been 3 times that I have had to stuff a ball of tin foil up Black Sabbaths bung hole in the back and shut the primary all the way down and sit back and hope the stove didn't rocket right outta the basement. And like you, it took me about 2 years to get the right feel for how to run my Oslo.
Thanks Butcher! Yes, I was referring to a start after an 8-9 hour burn. Sounds like I need to try shutting it down to half air a little earlier and let it burn there a little bit longer. And....it's good to know you are getting a similar secondary burn to me. I'll give the earlier and longer time at half air a try....let me add...you are a funny guy! Had me laughing in several spots.
Just remember, that was not a tutorial on how to run an Oslo. Just how mine works for me. Jotul has been building quality stoves for a long time and the Oslo aint cheap by any means but for heat out put I think I made a good purchase when I bought mine. What some folks have to keep in mind is that they are built for just that purpose, heat. The EPA is the 1 that put the regs on the smoke out put. Here in the flat lands of rural Iowa most of us don't really worry about the smoke. Hell, around here if you burn a brush pile or an old barn, 5 gallons of #2 and some old worn out tires is the norm. It looks like Beirut some times in the fall. Just play around with the stove and figure out what works best for you. Humans have been cooking and keeping themselves warm with far since the dawn of time. If it is easy enough for a cave man to do it I see no reason that we cant.
Sounds like your doing a pretty good job. Try out what Butcher said sounds like he is on track for sure. Dont be afraid to experiment try different things to learn for yourself how your stove does. Be aware of the type of woods you put in the stove and how you load the stove and then rememebr how that load burned and after time its will get easier. You get better secondaries from a fuller load of splits. As it leaves a smaller space in the top of the stove and this smaller heat space is easier to get up to temps to get secondaries. When your wood is really dry this is all so easy as the wood takes off fast and you can get the stove shut back down quick for a long burn and quick light off of the secondaries. If you leave the stove air open for a longer time your burning alot of the gases that would have given you secondaries. People with not as good as wood as they could have get a little less performance out of their stoves as it takes longer to get temps up due to the poorer or slightly more moisture wood. They end up burning up some of their bigg splits in the stove just getting the stove up to operational temps. Having said all of that sounds like your getting your stove shut down decently quick but maybe just letting it get a little too hot so like Butcher said get it shut down a little quicker and see how that goes. If you load on hotter coals then plan on shutting things down sooner. As the wood burns down after two hours like you said their is more open space in the stove so that can lessen secondaries and after two hours your wood may have out gassed all its gases so the wood could be at coal stage and 50% of the heat in wood is at the coal stage.
I had an Oslo for 6 years and for the last 2 I had nothing but problems with my burn times. The best I got on the last 2 years was 8 hours, nothing more and sometimes alot less. In the beginning (in 2007) it was going well, learned how to use it and trial and error brought me to 10 hr burns. Something happened along the way and I couldn't for the life of me, find what it was. I had the stove shop in to see the stove and a Jotul rep, they said it was in good shape. Wood was good, seals ok, no cracks etc...Needless to say the Oslo has a new home now. I hope yours is working better than mine did.
The Oslo is a 2 cu ft stove maybe a little more. So 8 to 10 hour burns are the range. 10 is hard to get but once in a while you can but 8-9 should be obtainable on a regular basis. Use the rake your coals forward method for longer burn times.
So when you guys rake your coals forward, do you leave the back with 3-4" of no coals, then put a split of wood on an area with no coals? Can anyone explain why this works? I know the air intake is at the front so it gets more air to the coals, but what else?
That's what I do and at the end of the burn I have a big hot coal in the back radiating heat. I don't have an Oslo but found I get a more consistent burn when I let mine get to 500 and then turn it 9/10ths down, if I get it hotter I get a lot of heat but then burns quicker and cools down quicker. 500 seems to be the sweet spot for mine, everyone has a different sweet spot though
From what I have gathered, raking the coals keeps some of the wood from gassing immediately. Essentially you won't gas it all at one time prolonging your secondary burn. I've had good luck with pushing the coals to the side....
Not that it matters, but the Oslo F500 (my model) has a firebox of 2.54 cubic feet. I can fit 4-5 decent size splits in it on a load.
I later learned that stove top condar was a little off so I would say the stove top was more like 750-800.
Thanks for sharing! I have been using that method some this week and it has helped me get a longer burn time. I have also been shutting the air back at about 450 instead of 500 and that has helped too. Thanks again!
