JOTUL OSLO F 500 poor air circulation

With the air coming into the combustion chamber in the front of the stove through the dogshack (the air inlet slider valve at the front that has the two 10MM bolts holding it together), it seems and is normal for an Oslo to burn front to back top to bottom. It is also normal for it to fully flame up as an extra air source (side door) allows extra air into the stove. Remember the Oslo is about 500 lbs of cast iron, it heats up slowly, but after it gets a head of steam going, it will burn for a long time (slowly). What kind of stove top temps are you reaching? Is this happening after startup from a cold start or when stove is being reloaded? Is your draft adequate for the stove to work properly and how is the wood supply? More info is needed. The F500 is a real workhorse of a heater normally excelling in every department- long burn time, supports longer pieces of wood, it has beautiful stove looks and its Jotul's best selling stove. Stay with her, she is a proven performer.

Sounds like wet wood. Have you checked it with a meeter?

My first suggestion would be a stove top thermometer. They are very cheap and give you a good idea of what's going on. A blazing fire in the box doesn't mean the stove is hot yet. Cast iron does take a while. Once the stove is heated up to optimum temps, assuming you have dry wood and good draw, those larger logs should ignite nicely.

Secondly, what is your chimney configuration? How high, what type of pipe and how many turns? Having enough height without excessive turns and material that is well insulated is crucial to getting proper draw.

Finally I think your dad is correct about ashes. Leaving some in the bottom is helpful.

We recently installed an F500 in our cabin and had similar issues when trying to burn wet wood. It sounds like your wood should be dry, but firewood is a tricky thing. The only way to know for sure is with one of those meters that measure it for you. It needs to be cut, split and stacked in a place with sufficient air. Even then some wood takes longer than others and local weather plays a big role too.

One more thought. It is worth checking to make sure your air intake and lever are working correctly. If something is wrong and it isn't opening up fully it's almost impossible to get a good fire going. I think you need to remove a couple bolts to get the dog house cover off. Then you can see if the lever is actually doing what it's supposed to do.

Sootfoot said:

I hear ya, I do use sleepers but normally I'll use 2x4's or similar because I don't have splits any shorter then 16". Will the jotul run better with little to no ash in firebox or does ash offer advantage?

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My F55 definitely runs better with an ash bed. My wife was cleaning it out the other day, thinking she was helping me. It was all I could do to just thank her and shut the hell up.

My Oslo acts the same way if I try to force it to burn wet wood.

Everyone seems to be thinking wet wood.... that is probably what it is. A stove top thermometer would tell the story. She should cruise at about 400-500 degrees with a full charge of wood at about 1/3 open air draft after you have heated up that 450 lbs of cast. On initial light off, I'd keep the side door cracked open (never the ash door, bad habit to develop) till the thermometer is reaching 300 or so, then close the side door and let temp build more and then slowly cut back air till she settles out. From cold start to 400 degrees stovetop tem should be around 40-50 minutes.. a lot longer than a comparable steel stove (like the PE you mention in your sig). That's one thing I do appreciate about my Enviro stove, the quick and easy get up and go. I still do like Blue Black Oslos though....

One of the most important things I've learned from this site is starting a fire. Like anything else, you need a good foundation to build on. I know all stoves are different. The most important thing is to have a good draw. Depending on your chimney set up some stoves can be stubborn to start. What works for me maybe will work for you. After I load all my starting material, a few pieces of twisted newspaper, a few small pieces of cardboard covered with small twigs and then some larger dried small dead branches. I take a lit propane torch and position it at the top of the stove (from inside the firebox) towards the chimney outlet moving it side to side for a count of 20 seconds. This allows heat to start pulling up threw the chimney pipe. After the 20 seconds I light my starter material and close the door. I also open the small vent on the bottom of the door till the fire gets going. The twigs and small dead branches I collect and lay around the bottom of one of my trees in the back yard threw the summer. I'm also a firm believer in keeping a nice bed of ashes in the bottom of the firebox.

Random thoughts . . . but mostly just regurgitating what others have said . . .

For me the time to get the stove going from a cold start to where I can start getting some heat from it is anywhere from half an hour up to an hour . . . the Oslo is more of a long distance runner than a sprinter . . . takes a bit to get going, but once it gets going it keeps going and going and going.

Love the top down fires . . . feels strange to not do top down fires now.

The wood may be the issue . . . try the top down fire, but use smaller splits. I generally only use the largest splits (8 plus inches) on overnight fires. Most of my fires use small to medium sized splits and on cold starts I use a decent amount of kindling to get the fire going. Again . . . it takes a bit to heat up the iron. In general I find larger splits = longer burns, but not as intense burns. Of course there is always a chance the larger splits are still not seasoned enough . . . or it could be that your stove is actually working fine and the wood is good -- just very large and so you're not getting as much of the surface burning.

Stove top and flue thermometers are very useful . . . lets you know when you can shut the side door . . . and when you can cut back the air control to get a good, sustained secondary burn.

Checking your air control is worth looking at . . . a quick, 5-minute check with a 10mm socket wrench . . . and after determining whether the slider is working right (I suspect it is though) you can add some graphite powder to help the sliding mechanism stay lubed up.

Father knows best . . . yeah . . . these stoves do better with an inch or so of ash in the firebox. Resist the temptation to clean them out. Empty the ash pan . . . but leave some ash behind in the firebox.

Not sure if it helps, but here's how I get my Oslo going. I make the top down fire placing larger splits at the base, medium splits on top and then some kindling followed by a chunk of Super Cedar . . . sometimes I'll toss on some cardboard for extra measure. The air control is open all the way and the side door is ajar . . . as mentioned . . . do not use the ash pan door (and yes . . . Jared Willey . . . if you're reading this I am thinking of you!). I light the Super Cedar and then sit back to watch the fire, surf the internet on my tablet or watch TV . . . all the while watching the fire and the thermometer slowly increase. I have both the stove top thermo and a probe thermo for my double wall pipe and truthfully I rely more on the probe thermo. Once the temp on the thermo is close to or in the "good to burn stage" I shut the side door . . . and watch the fire. If the flames are sustained after 5 minutes I will start closing down the air in quarter mark increments . . . and do so every 5 minutes or so. If the wood is good and the fire is hot enough the fire will continue to burn, the stove will start ticking ("the sound of heat" as my wife calls it) and by the time I get the air control down to the quarter closed point I should have a good secondary burn going.

Sootfoot said:

I find my olso just doesn't burn properly. If I open the side door I can get a roaring fire going, but as soon as I close the door all the flames at the back die out in seconds and just the wood close to the front door burns well. The wood at the back just smoulders, as soon as the door is opened all firewood catches on fire and start to roar again. It seems like the flames at the front of the stove eat up or hogs, all the air being drawn in for combustion. This is frustrating, and it seems to be effecting the amount of heat I get out of my stove.

Thanks

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Your description above describes EXACTLY what my problem was when I installed my Oslo a few years ago.

In my case, I knew it was not the wood--it had been CSS and under cover for about 4 years.

I think it was begreen who suggested that it might be a draft issue. I added 1 foot of pipe...no difference...I added 2 more feet and there was a difference--not great but way better. I added 2 more feet and wow...problem solved!! I did have to brace the chimney up top but that was a small price to pay to get the Oslo to perform as it was designed to do!

Try this with cheap single wall pipe. If it works, then replace the cheap stuff with permanent certified pipe.

Good luck!

The issue maybe a bit of all of the above. Early season burning when the outside temps are not so cold, the draft may not be so good. chimney height. Splits that go out are may be wet. A bed of coals works best for me, because most of the time I don't need a hot fire. So with dry wood I can drop one or 2 splits on a bed of coals, and it burns down just fine.
So I'd get all the small splits you got, criss cross them so you have room between them. Get them ripping with the side door open, then close it when you have every thing burning well. Add wood when ever there is room. Get a 3 inch bed of coals, and then you should be able to burn marginal wood. You should be able to get the top back right corner to 500 degrees.

Our oslo ran the same when the stack went I to a thimble and over sized masonry chimney.
Swapped it out with all class A pipe and it was like a new stove.
Also ran poorly the year we tried to force it to burn wet oak, live and learn.

I just got a liner this year and am noticing more consistent heating. 475 was about as good as I could get sometimes. Now seems to shoot thru 525 pretty easy. Haven't needed big fires yet. But kind of excited for some cold weather to see what that draft can do. As for those "sleepers". I used some 1" angle iron as sleepers last year. Made it easy to create the tunnel folks speak of.

Sootfoot said:

Any good suggestions where to get a stove top therm?

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Amazon has lots of them between $15 and $25. Any store that carries wood stoves would probably have them as well.

I'm partial to Condar thermometers.

firefighterjake said:

I'm partial to Condar thermometers.

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Agreed. This one is fairly accurate.

http://www.amazon.com/Condar-330-In...46687468&sr=8-1&keywords=Stovetop+thermometer

Sootfoot said:

Wow you guys are incredible. Im offline for 2 days I come back and here's all the help I could possibly ask for.

Took me 20 minutes to read all the replies!

Ok so I have about 16' superflu double walled chimney, all SS. I purchased the piping used from a guy who had a cottage and rarely fired up his stove.

I did put another section on it last year, but maybe I should add yet another. I only have a 1100 sq ft bungalow and the chimney is about 3' taller then the peak of the house and seems to be towering over it from a distance. But if another length makes a big difference then it's worth it!

Any good suggestions where to get a stove top therm? I like the idea of angle iron for sleepers. My wood might be a bit moist just from humidity, no question it's dry. I do have some pieces larger then others, but I guess I'll just have to keep a half face cord inside beside the stove ( safe distance) to dry more.

Can anyone recommend a good ash vacuum that isn't 500$? I got an 80 $ one from princess auto and it was garbage. A nice one would help out a lot especially for that front door and behind ash drawer.

Thanks champs.

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Stove top thermostats can be found easily almost anywhere for a couple of bucks. I got my Condar thermostat from Amazon too. As far as a dust vacuum, I'm not familiar with them. I think since ash is so fine it would probably clog any filter within a short period of time and or kill the vacuum. An inexpensive dust pan with its' broom will work fine.

I agree with FFJake's description. I have struggled occasionally with our F600 but once I got all the deferred maintenance taken care of, a slow start/smoldering was almost always some combination of me rushing to close the side door too early, crap wood or not sufficiently cold outside yet for a good draft. Once these cast stoves warm up, they will keep running pretty easily, IME.

And we do not have a very tall chimney, although we are going through a good liner with a block off top and bottom.

The guys here got me using a thermometer almost immediately and I rely on it completely for timing the door closure.

Have you checked to make sure that there is nothing blocking the bottom air intake (legs on?), and that the top cast plates and blanket are all in the right place and in good shape?