Jotul Oslo Secondary Burn??

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yellowstonebanks

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Feb 9, 2007
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I have a Jotul Oslo now in it's second season and I am wondering if it is operating properly. The manual indicates typical stove-top temps of 400-600 but I rarely see temps much over the low 400's. Compared to other stoves I have used with this sort of secondary burn technology I don't see a lot of action up around the secondary burn tubes. The draft seems reasonable since I can start fires fine and they burn well with air control anywhere between full open and 1/2 open. At those settings with enough wood I can get a nice steady burn (mostly from the bottom) and stove-top temps around 400 or a little higher. At that point if I close down the air control I will initially see some nice flames around some of the top tubes but it won't be long before things die down and I have a fire with few flames and not much action up high and stovetop temps dropping into the 300's. Is this normal for this stove or is something amiss?

Stove is located in a first floor fireplace of a 2-story house. There is a continuous chimney liner down the brick chimney, must be 25'-30' put in by the stove installer. When cleaned this fall after burning maybe 2 cords of wood last year there was a good amount of fine soot but not much evidence of creosote. I do tend to have relatively short hot burns and tend not to load up the stove and shut down the air intake.

The stove has run this way since we purchased it. The only thing I can think of is if somehow air flow into the tubes is obstructed. Is this possible or seen by anyone else? Any way to easily check for this?
Thanks for any comments
 
My first thought would be that the wood you are burning isn't really dry.
I have an Oslo and when I pack it full of dry wood I can easily run it near 600 with the primary air shut down 3/4 of the way. And the secodnary burn is very noticable. However, the few times that I have used wood that wasn't as seasoned I would immediately notice a loss of secondary burn and would have a much harder time keeping the stove near optimum operating temperatures.

That would be my first guess (actually my only guess since I am pretty new to the stove), but you should be able to get that stove really hot.
 
yellowstonebanks said:
I have a Jotul Oslo now in it's second season and I am wondering if it is operating properly. The manual indicates typical stove-top temps of 400-600 but I rarely see temps much over the low 400's. Compared to other stoves I have used with this sort of secondary burn technology I don't see a lot of action up around the secondary burn tubes. The draft seems reasonable since I can start fires fine and they burn well with air control anywhere between full open and 1/2 open. At those settings with enough wood I can get a nice steady burn (mostly from the bottom) and stove-top temps around 400 or a little higher. At that point if I close down the air control I will initially see some nice flames around some of the top tubes but it won't be long before things die down and I have a fire with few flames and not much action up high and stovetop temps dropping into the 300's. Is this normal for this stove or is something amiss?

Stove is located in a first floor fireplace of a 2-story house. There is a continuous chimney liner down the brick chimney, must be 25'-30' put in by the stove installer. When cleaned this fall after burning maybe 2 cords of wood last year there was a good amount of fine soot but not much evidence of creosote. I do tend to have relatively short hot burns and tend not to load up the stove and shut down the air intake.

The stove has run this way since we purchased it. The only thing I can think of is if somehow air flow into the tubes is obstructed. Is this possible or seen by anyone else? Any way to easily check for this?
Thanks for any comments
Click to expand...

Hmm . . . first thoughts . . . make sure the wood is truly seasoned enough? Are you also loading the stove full?

Maybe try loading some splits and rounds on the smaller side (if you have access to some good kindling or pallets try some of this -- not too much though to avoid overfiring) . . . I can get the temp up pretty quickly with small splits and/or pallets.
 
Can you easily get the stove up to high temps with the side door cracked open?
If not, then you probably aren't dealing with an air obstruction issue but rather something else.
 
Try opening your air box to check on the sliding metal allowing full air intake when the lever is all the way open to the right.
There are 2 bolts holding the cover inside the stove. It is a simple mechanism and easy to see if it is operating correctly. The holes in the cover should be clear.
If you have an air compressor or can of compressed air, blow it through the rear air intake for the primary air to be sure that it's not clogged with something like furnace cement.
Like the others, our Oslo will easily get to 600 F with the thermometers on one of the top corners of the stove. Since I have OCD, I use 2 thermometers on diagonal corners. Morning fires are hot with the ash door open until the temp reads 500 F -600, then closed, and the air adjusted to where we want it, usually running around 400-450 F.
As the others said, if you're using wet or unseasoned wood, your flue or chimney cap may be clogged.
Good luck, the Oslo is a reliable heater.
 
Thanks for the replies, this years wood was delivered late last winter and has been in my garage all summer and fall so it is definitely not green but maybe not completely dry. I tend not to load up the stove too full and the splits I've been using this year are pretty big so I can try more smaller pieces and a fuller load... When I open the side door a little I get almost a blast furnace effect so I haven't left it open with an established fire long enough to see what the temps would get to. I guess I'll have to snoop around the air intake to see if that looks ok...

Any other thoughts?
Thanks
 
Have you had time to check your inlet? If it is ok, my guess is that you haven't put in enough would. The Oslo's firebox is pretty big, if you just put in 2-3 medium pieces you probably won't get a long secondary burn.
 
yellowstonebanks said:
... this years wood was delivered late last winter and has been in my garage all summer and fall so it is definitely not green but maybe not completely dry.

Any other thoughts?
Thanks
Click to expand...

You may be onto something.

We had a case almost a month ago about some wood that was stored in a garage during the summer. The wood would burn but there were some issues that brought the matter to the forum.

It was discovered that the wood was still too green. Evidently, being shielded from the wind and sun prevented the wood from seasoning or drying out below the 20 percent moisture level that is required.

You can test this for yourself with a wood moisture meter. I have one that cost about $20 from Harbor Freight and it has been good to have. Just re split a few pieces of you firewood or drill a couple small holes to take the reading below the surface and you are instantly able to tell if you wood is really dry enough to burn properly.

At this point it seems that your stove and set up is excellent. On the other hand, it seems that what you are experiencing is very similar to the effect of burning wood that still has too high of moisture content. I recommend testing your firewood with an inexpensive wood moisture meter to see if that is the cause.
 
Mine seems to be more wood fussy than any stove Ive had. I just noticed I loaded some oak in there that even over a year old, its hissing. Moisture is evedent on the log ends. Im having to leave the door open to get her cranking. I think Oak, hickory sometimes needs to set two years before its ready
 
Relative newbie- so take this for what it's worth. I find mine works better if it gets up to 500+ before begining , in steps, to close it down to half. At that point the secondaries will start, and it will climb slowly. Ends up not quite closed for overnight. Smaller wood to crank it- really is happiest pushing 600 on top. But I worry I'm burning to hot and wasting wood!
 
I forgot to mention that I also need to see 5 or 6 hundred before I close the air down. I keep it open 1/8 inch during
 
I wasn't getting above 350 with my first load of wood which was partially seasoned. Now with new wood and a mix with Envi-8 blocks I have no problem getting above 500. I pack the stove with 6 blocks and surround them with wood, first smaller splits which I let burn down a bit and then with larger splits. I keep the side door open a crack and the air on full throttle until she is raging. Then I close the door and let the temp get up to ~550. Then I throttle back the air slowly, Secondary kicks in almost immediately. After ~ 7 - 8 hours stove drops to 200 and I repeat.
 
Sorry also a noob Oslo burner (day 2 - in fact). I noticed this morning that when I put fresh splits on a nice bed of coals and opened the intake to full, I still had to crack the door to get her crankin'. Otherwise, if I closed the door she would die right back down. In one of the previous posts here I saw mention of checking the air inlet in the front and something about one in the back. I've seen the one in the front and figured it might get clogged with ash from time to time, but I haven't seen the one in the back. Where is it?
 
I find with all of my stoves that a good hot established coal bed is the key to secondary burn. Whether it is spread under the new load for a fast hot burn or raked to the front for a longer burn the hot coals are the driver for getting it up to temp and good secondaries going.
 
BB hit it with being able to get a to good secondary burn easily. You can still get there with wood that is less than optimally seasoned - it just takes longer. Once you get the thing burning pretty well, as in my Castine, it is much easier to get some secondary burn if you fill the firebox a bit - if not all the way.
 
I find it strange that you can't get much over 400 with air between half and full. I don't see how air tubes could be clogged and any clog in the main inlet would also be evident on the primary. I've seen similar behavior with wet/green wood or when its' 40's and near 100% humidity. But even then, it's usually curable by starting out with more small splits and just running up the stove temp with the primary air.
 
Best test: head to home depot, lowes, grocery store and get 2-3 bundles(depending on your firebox size as little as 1 or as much as 5, you want enough to be able to make a coal bed then load it up full)of the kiln dried firewood they have there. Load it up a little, get a good coal bed going, then load it up full. Check your secondaries at that point.


I'm willing to bet that the wood is the culprit here as wood will not season well in your garage without direct sun, wind, and rain.
 
CZARCAR said:
wonder what those secondary tubes do when the flames arent present= cool off the stove? with excess air.
Click to expand...

Yep.
 
I have a new Jotul 500 this season and can affirm that it is the most fussy stove about having truly dry wood of any stove I've ever used. Green wood will not burn at all. Wood that is only partly seasoned will achieve secondary burn only with difficulty and then only with the air control half open or more. With dry wood, what a difference! Longer burn times, higher temperatures, and near set-it-and-forget-it on the air control. My Dutchwest cat stove out in the shop is much less particular and will happily burn wood that has only been cut eight or ten months.

A couple of points: Although I may be mistaken, it seems not to run as well if the ash pan is totally full. Not sure why this should be. And I have had a small, but observable problem with a thick bed of coals seeming to block off the front air control. I have taken to shoveling the coals to the BACK of the stove on reloads, which is totally contrary to everything everyone has ever said on these forums. But since I started doing this the stove gets back to temperature faster and the coals burn more completely.

But to return to the dry wood issue, I am currently cutting and splitting for winter 2011!

Mark
 
jotul8e2 said:
Although I may be mistaken, it seems not to run as well if the ash pan is totally full. Not sure why this should be.
Click to expand...

Same here. My conclusion was simply that air can't get underneath or on the sides as well. I have a Heartstone Pheonix too which behaves the same, but not as bad.
 
New to the stove this year, so I've done a lot of experimenting with it. For a good secondary you need a hot fire, more and smaller splits will accomplish this. Once you have things positively glowing inside, kick back the airflow to about 1/3, and you should have a very noticable division between flames on the logs, and a swcondary up top. If you only build small fires, you will not accomplish this.
 
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