Jotul F500 Oslo Burn Time Issues

[NewEnglander]

Hello all,

I have a relatively new, few months old, Jotul F500/Oslo. I bought it because everyone was saying how it would heat your whole home for cheap-er, plus, we just wanted the ambiance of a fireplace/stove.

The issues I'm having with this is that they boast 9 hour burn times. Currently, no matter how I stack it, or how I burn it, I'm looking at what I would call 3-4 hour burn times max. When I get up at 6am after filling it at 11pm or later, theres not even enough hot coals to relight it.

The wood is NOT the issue, I have excellent seasoned hardwoods, the guys from the store, and other wood burning people have said this is top quality hard oak, seasoned over a year.

I loaded it densely, with hard oak, I cross cross them etc, but still 3-4 hours burn time max. After 3-4 hours I was left with the below, it will only hold temps 400-550 for about 3 hours then drops. Cant quite figure it out but really disappointed with this stove, I seem to be loading it full way to often to enjoy.

The picture is whats left after 3 1/2 hours from being completely packed full.
It doesn't rage out of control, I cut it back (the air lever) as soon as I can, it doesn't go above 600F max, it just seems to be burning very inefficiently

 

[begreen]

Welcome. Try not criss-crossing the wood. Instead, pack it tightly with the wood parallel to the glass, all in one direction. Also, at what stove top temp is the stove being reloaded? How thick are the average splits that are being burned?

I'm wondering if the draft is excessive. How tall is the chimney system on this stove?

 

[marajade]

We are getting max 3-4 hour burns off our new oslo but I can only blame myself at this point because we have yet to pack it densely... Then again we usually just burn in the evenings and we aren't trying for an overnight run.

 

[claydogg84]

I load my Oslo at 9:00 PM and have plenty of coals left for an easy relight at 6:00 AM. Actual usable heat lasts about 5 - 6 hours max. By usable, I mean stovetop temps above 300. How much are you shutting the air down? If your wood is as good as you say, you should be able to shut the air completely off, or nearly there. I shut down mine to a little under 1/4.

 

[Nick Mystic]

If, as you say, you are holding temperatures between 400F to 550F for three hours I'd say you are doing pretty good with the Oslo. I would expect it to take another hour at least to drop to 300F, so that's a pretty good heat cycle from this stove. I have a Jotul F 600, the Oslo's big brother, and I don't get much more performance from my average load of 3 or 4 good size oak splits. You have to realize that when forum members start talking about getting 8, 10, 12 hour burn cycles out of their stoves they aren't talking about the stove holding 500F for 12 hours. When I hear some of the burn times reported I figure there's a bit of exaggeration in some of the higher figures. When most people say they got 10 hours out of their stove they are probably talking about being able to root around in the ashes and locating some hot coals. They aren't talking about 500F temperatures for ten hours.

 

[Rearscreen]

Hi, NewEnglander, I'm pretty new to this forum also, and if you click on my screen name you can read some of my past comments from my experience about the Oslo. Basically, last fall I moved in with my new girlfriend who had this stove. Within a month I ordered and spent upwards of $3,300 on another stove to replace it. When she told me how many cords she burned a season I freaked. Today when she looks at the woodpile outside she can't believe how little we have used (our primary source of heat). As far as burn times, I never believe what any manufacturer says. Even the one I got falls short. But, again that's why my last 3 (or 4?) woodstoves have been soapstone. At least, in the morning with the coals black, the stove is still warm.

 

[begreen]

An overnight burn in the Oslo is possible. Several folks here do this and have burned 24/7 for several years in the F500. But it depends on how hard the stove has to be pushed in order to keep the house warm. Besides the stove and how it's operated it also depends on the wood, the house's heat loss rate and the outside temps.

 

[claydogg84]

Hi, NewEnglander, I'm pretty new to this forum also, and if you click on my screen name you can read some of my past comments from my experience about the Oslo. Basically, last fall I moved in with my new girlfriend who had this stove. Within a month I ordered and spent upwards of $3,300 on another stove to replace it. When she told me how many cords she burned a season I freaked. Today when she looks at the woodpile outside she can't believe how little we have used (our primary source of heat). As far as burn times, I never believe what any manufacturer says. Even the one I got falls short. But, again that's why my last 3 (or 4?) woodstoves have been soapstone. At least, in the morning with the coals black, the stove is still warm.

I'm fairly certain telling him to buy a soapstone isn't going to help him learn how to use the Oslo. My Oslo heats my entire home (2,000 sq ft raised ranch) all winter long, even in negative temperatures. It's a very capable heater when used correctly - Which I believe was the problem you had with it, Rearscreen.

 

[JonOfSunderland]

"top quality hard oak, seasoned over a year"

Wet wood.

 

[brad wilton]

was just about to say samething don't have much oak in these parts but from what i've read on forum 2 to 3 years in well ventilated area is what you'll need to dry properly

 

[rideau]

Claydogg84, why not post details for him of exactly how you load and burn to achieve those burn times? There may be some aspect that he isn't doing that will help him significantly.

 

[claydogg84]

Claydogg84, why not post details for him of exactly how you load and burn to achieve those burn times? There may be some aspect that he isn't doing that will help him significantly.

Sure. First off, I'm burning all hardwoods, mostly black locust and sugar maple. I load on a full bed of coals - Some rake the coals forward, I make an even bed of them in the stove. I load as much wood as I can fit in the stove, even laying it in the front against the glass (some people will say not to do this - No problems for me aside from maybe a dirtier glass). I leave the side door cracked to get the temp up to 500 or so, then I shut the door for another 5-10 minutes until there is a good amount of flames and the temp should be around 550-600. At that point I start dropping the air down in stages - You should be able to get it down in 2 drops. My first drop is right above half, and then after 7-10 minutes I will drop it to about 1/4 open. With the air shut down that far you should see mostly secondary flames at the top of the firebox and maybe a few lazy flames coming from the wood. If you're struggling to shut the air down and achieve secondary combustion, chances are your wood isn't dry enough. Secondaries should ignite for 1.5-2 hours giving you a stovetop temp of 500 or so. After that, the wood will take over the flames and temps will range from 400-450 for another 1.5-2 hours. The last stage is the coals - this is when temps will start to dip lower than the 300 mark. You should be able to get 300+ for 5 hours, and then the heat output will significantly decrease. Hopefully this helps.

 

[NewEnglander]

Hi all,

Thanks for so many replies. I've tried every way going of stacking the wood. Today I tried cross cross and still no better as others suggested I try that.
I'm probably only getting two hours of 500F temps.

I never ever expected 10-12 hours of 500F, but I expected 5-6 hours maybe of over 400F.

The wood is good, I'm certain. The packing is nice and tight no gaps, I pick every log to fit snug. I've packed against the glass and not against it.

The chimney is a center chimney maybe 30-35 feet, and to combat excessive draw I've tried placing steel wool in the air inlet in the center back bottom of the stove as advised by the store, works a little but not enough.

Tried a 6" liner, and a 5.5" to combat the draft, so I'm at a point where I'm confident it was installed right.

Lastly, and this is my issue. I've noticed the side door handle does not fit tight like a spring the way the front door does. Also, it doesn't do the dollar bill test like the other doors. I can pull a sheet through the door when shut, I can't elsewhere on the other doors.

I replaced the gasket, still no better, even tried replacing the door with a door from a brand new stove, it was even worse.

My suspicion is now a manufacturing defect......

After 3 hours it looks pretty empty as per the photo in the thread.

By 3 hours temps have now come under 400F, they only stay up there at 500-600 for two hours MAX!

The lack of hot coals the next day at 6 or 7am, all gone to just ash from a full load at 11pm the night before.

Any other suggestions?

 

[claydogg84]

How much are you shutting the air down, and are you getting good secondary combustion? Realistically, you're probably only going to get 4 hours of 400+.

 

[NewEnglander]

How much are you shutting the air down, and are you getting good secondary combustion? Realistically, you're probably only going to get 4 hours of 400+.

Yes, I bring the temps up to 450-500 and shut it down 50% then wait a min or two then shut down again, then shut down to zero!

I think the door is the issue or the stove, if I didn't turn the air down the temps would go up over 600, I control it pretty well

 

[begreen]

Criss-crossing the wood adds a lot of air space to the fire. That will make it burn much faster. I would definitely add a key damper to the flue pipe to reduce draft strength. You can probably operate the stove with the key damper all the way closed once the fire is burning well. This will be more effective than the steel wool.

 

[claydogg84]

Yes, I bring the temps up to 450-500 and shut it down 50% then wait a min or two then shut down again, then shut down to zero!

I think the door is the issue or the stove, if I didn't turn the air down the temps would go up over 600, I control it pretty well

Are you getting flames from the secondary tubes, or off the wood?

 

[Rearscreen]

What my girlfriend did over the years to get more out of the stove was to disregard the ash pan altogether. She'd let the coals build up to the point where they would be above the grate. To empty the ashes she's just use a shovel using the front door. One problem she always had with the ash pan: after emptying the pan some would fall way in back and then the pan wouldn't go all the way back in. With her method, it kept a bed of coals happening. I balked at this method (as a typical male jerk who was questioning someone who has used this stove for many years) and cleaned the stove completely replacing gaskets that needed replacing. I mentioned that the air intake is being blocked by ash and needs to be kept clear. I also added an outside air intake. Upon firing it up for a couple of weeks using my less ash method it wasn't working well. Then I just let the ash build up and it worked much better. She was correct.

 

[NewEnglander]

Yes she is correct
I do the exact same I never open or empty the ash pan I let it build up


Also I never criss-cross the wood I just did it to prove that doesn't help, others suggested it

I do see secondary arora borealis type flames bouncing around from tubes or wood? I don't know

 

[begreen]

Install a key (butterfly) damper. The chimney height is too tall.

 

[NewEnglander]

Install a key (butterfly) damper. The chimney height is too tall.

Yeh we did consider that but the store said it increases creosote build up!
We may just try that

What about the dollar bill test? I can pull it through the gasket when shut tight

 

[claydogg84]

I think you're asking too much from the stove. 3-4 hours of 450-600 stovetop temps is pretty good. Is this your first wood stove? Companies mislead customers with ridiculous burn times, and that usually leads to confusion when actually using the stove. How much space are you trying to heat with the Oslo? If you're in need of 500+ stovetop temps continuously then there are other problems such as an undersized stove for the space, insulation, or drafty windows/doors.

 

[begreen]

Yeh we did consider that but the store said it increases creosote build up!
We may just try that

What about the dollar bill test? I can pull it through the gasket when shut tight

They were wrong. Burning unseasoned wood or letting the stove smolder will build up creosote, not the key damper. You'll note that in your stove manual this is what Jotul recommends for tall chimney with strong draft.

Is there some resistance to the dollar bill or none at all?

 

[begreen]

There has been discussions about outside air intakes, I'm no smartie pants so may need some input. Over the years, when I did add one, the stove seemed to perform better. It seemed that the colder the air going into the stove, the better it responded. Is there any science to this? Am I imagining this?

Separate topic completely. Sounds like this stove is over-performing due to strong draft. This article should be helpful: http://www.chimneysweeponline.com/hooa.htm

 

[NewEnglander]

I really disagree that I'm asking too much of the stove.
All the wood is gone from fully packed to hardly anything within 3-4 hours, 4 is pushing it, the temps are 400-600 for about 3 hours!
If that's asking too much ......

As for the dollar bill there is pretty much no resistance on the side door, but I can't pull it through the front or ash door