Jotul F500 Oslo Burn Time Issues

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
  • Super Cedar firestarters 30% discount Use code Hearth2024 Click here
Your stove has two (2) air sources for combustion:

1. Primary, the variable lever at the front.
2. Secondary, the fixed air supply from the three (3) tubes above.

You can only control the Primary air, by that lever. Nothing else!

Does moving the Primary air lever all the way to the left significantly reduce the fire intensity?

Or... does the fire burn intensity remain the same?
 
Earlier you mentioned that the side load door did not feel as snug as the front load door. Both latches use a spring to adjust the tension. There is a chance the spring has failed and is causing most of your issues.
 
OK

Within 1 hour and 52 mins, the temp is now dropping below 400F, despite being fully loaded, and despite the air closed completely……

I don't care what anyone says, but this is not asking too much of a stove that cost in the region of $3,500!

At this point ill install a butterfly damper, but I'm going to demand a new stove from Jotul tomorrow, handing someone cement and larger gaskets than those recommended on the stove after just 2 months of using the stove and telling them to deal with it is a pretty chitty response….

You can agree or disagree with me on this one but I've spent enough of my time on this issue, its a brand new stove and I paid a pretty premium price
 
Hello NE, Ok, we've established now that the largest cast iron wood stove maker in the world who has made cast iron stoves since 1853 has made a terrible stove for you. Where did you buy this stove?? Have you given the dealer a chance to look at this stove/install and correct it making you so unhappy?? Did the installer correctly install this stove?? Is the flue outlet correctly mounted and not leaking air into the stove?? Is the 35 ft chimney a vertical run only?? If so, an inline damper would probably help. What is the tested Moisture of your wood?? Are you loading fully to the air tubes (but please don't pry on the secondary burn system getting that "last piece of wood in there" and knocking them loose too)? I see and hear this story many times, but when the dust settles, its usually just wet wood, or improper operation. Oslos are as good as a stove gets, not perfect but it is prob the most popular cast stove in the US... you know it gets pretty cold in Norway. I'm not trying to belittle you, just imploring you to be reasonable. I know this stove extremely well, it doesn't disappoint very often. If you get no where with your dealer to help get your issue resolved, go to Jotul or another dealer for help. Good luck. BTW, I'm hoping you meant $3500 for the stove and install.
 
My girlfriend said just now, oh my God, it's so hot in here. 20 degrees out 80 in. I'm on the lowest air intake and only a few sticks in in the most drafty house on the planet. What if, just possibly, some stoves are designed better than others? I'm not necessarily touting my stove over others. Through this forum I have learned about Blaze King which, trust me, I will research further. Never heard of it before this site. I like what I see.
Are some just throwing darts and putting band aids on a product that is inferior? My stove is not perfect. I see how they have applied their own band aids to correct immediate problems. Stupid stuff that I know they will build into future designs that they have learned from, from their customers in the field. Any advanced designs have to have problems. I do know, with the same draft, same situation, this house is much more comfortable with 50 per cent less wood being used. The original thread was how much this stove is burning wood in a short period of time. Exact problem I had. I have a stainless 6 inch pipe 20 feet up inside a chimney. Once I replaced the stove in an exact situation the results were night and day. I just think others could learn from this real information. Even the manufacturer.
 
I don't know if the Oslo has the exact same side door handle mechanism as the F600 that I have, but on mine I can adjust the tension on the door by tightening or loosening the nut on the inside of the door. If you have a nut on the handle mechanism you might try snugging it up a little and see if your side door closes tighter.
 
For those who do care what others say, here are some facts (Inconvenient things, facts. But useful for some):

Oak has about 7500 btu per pound. The Oslo is rated by Jotul for a maximum output of 70,000 btu at an efficiency of about 75%. To achieve those 70,000 btu output will take 93,333 btu input. Oak has about 7500 btu per pound, so for each hour at maximum output you will need 13 pounds of properly seasoned oak. If you are using oak "seasoned more than a year", you will not obtain anything like this output as it takes three years after being cut, split, and stacked to be properly seasoned.

So if you can somehow stuff 40 pounds of oak into an Oslo, you can, in theory, go three hours at maximum output - which would be a stove top temperature of 550 to 600 degrees. 40 pounds, 7500 btu per pound is 300,000 btu input, 225,000 btu output, 70,000 btu per hour for just over three hours. At that point there would not be a single atom of wood left. It is obviously not possible to burn a load at maximum temperatures to the last atom of firewood, therefor expecting four or five hours of 550 to 600 deg. stove top temperatures on a single load is fruitless - it is not in accord to the laws of physics. This is not in any way affected by the price of the stove.

More reasonably you will load perhaps 30 pounds of wood on top of a bed of coals and generate maybe 50,000 btu during the first hour, 30,000 or so the next couple of hours, and less than 10,000 btu in each of the last two hours of a five hour cycle.

For those who need longer burns at higher btu outputs there are larger stoves.
 
For those who do care what others say, here are some facts (Inconvenient things, facts. But useful for some):

Oak has about 7500 btu per pound. The Oslo is rated by Jotul for a maximum output of 70,000 btu at an efficiency of about 75%. To achieve those 70,000 btu output will take 93,333 btu input. Oak has about 7500 btu per pound, so for each hour at maximum output you will need 13 pounds of properly seasoned oak. If you are using oak "seasoned more than a year", you will not obtain anything like this output as it takes three years after being cut, split, and stacked to be properly seasoned.

So if you can somehow stuff 40 pounds of oak into an Oslo, you can, in theory, go three hours at maximum output - which would be a stove top temperature of 550 to 600 degrees. 40 pounds, 7500 btu per pound is 300,000 btu input, 225,000 btu output, 70,000 btu per hour for just over three hours. At that point there would not be a single atom of wood left. It is obviously not possible to burn a load at maximum temperatures to the last atom of firewood, therefor expecting four or five hours of 550 to 600 deg. stove top temperatures on a single load is fruitless - it is not in accord to the laws of physics. This is not in any way affected by the price of the stove.

More reasonably you will load perhaps 30 pounds of wood on top of a bed of coals and generate maybe 50,000 btu during the first hour, 30,000 or so the next couple of hours, and less than 10,000 btu in each of the last two hours of a five hour cycle.

For those who need longer burns at higher btu outputs there are larger stoves.

Heres some more facts that we should also mention: Of course taken from Jotul N.A website.

"it will burn for almost 9 hours"
I loaded mine, packed tightly full, just 3 hours 41 minutes ago, theres hardly a red coal left…….I would love to see how they call it a 9 hour burn!

"70,000 BTUs per hour" - Not a chance!

"patented spring loaded door handle" - Thats the same one that doesn't work after just 6 weeks, even a brand new one didn't work

"easily extend burn times with Jotul's single control lever" - I tried that earlier and my temperatures still kept increasing and increasing, without my control.

I reckon hearing this too is inconvenient for some.

So lets ask, given those facts,

Q. What they define as "burn time"? What temperature is the lowest, and obviously maintained for 9 hours.

Q. Under what conditions did they get that burn time of 9 hours and was it repeatable?
Chimney Length
Insulation quality
Outside temperature
Log condition seasoning/split/stacked/species
Home size, ceiling height
Weather conditions at the time humidity/pressure/wind/temperature
etc

Q. When they reach 70,000 BTUs how long does it stay at 70,000 BTUs and what was the burn time then once 70,000 BTUs is reached.

Q. Can it heat a 2,000 square foot home, in New England, for 9 hours, at 70,000 BTU's?
If not, then for how many minutes can it heat a 2,000 square foot home at 70,000 BTU output in a New England winter.

Without answering these facts that they state, then its just a pile of gibberish nonsense that comes at a significant cost to the consumer and is deliberately misleading and the cause of a lot of frustration.
 
Last edited:
My girlfriend said just now, oh my God, it's so hot in here. 20 degrees out 80 in. I'm on the lowest air intake and only a few sticks in in the most drafty house on the planet. What if, just possibly, some stoves are designed better than others? I'm not necessarily touting my stove over others. Through this forum I have learned about Blaze King which, trust me, I will research further. Never heard of it before this site. I like what I see.
Are some just throwing darts and putting band aids on a product that is inferior? My stove is not perfect. I see how they have applied their own band aids to correct immediate problems. Stupid stuff that I know they will build into future designs that they have learned from, from their customers in the field. Any advanced designs have to have problems. I do know, with the same draft, same situation, this house is much more comfortable with 50 per cent less wood being used. The original thread was how much this stove is burning wood in a short period of time. Exact problem I had. I have a stainless 6 inch pipe 20 feet up inside a chimney. Once I replaced the stove in an exact situation the results were night and day. I just think others could learn from this real information. Even the manufacturer.

For the second time - This thread is to help the OP learn how to use their Oslo, not why they should purchase a different stove.
 
Last edited:
OK

Within 1 hour and 52 mins, the temp is now dropping below 400F, despite being fully loaded, and despite the air closed completely……

I don't care what anyone says, but this is not asking too much of a stove that cost in the region of $3,500!

At this point ill install a butterfly damper, but I'm going to demand a new stove from Jotul tomorrow, handing someone cement and larger gaskets than those recommended on the stove after just 2 months of using the stove and telling them to deal with it is a pretty chitty response….

You can agree or disagree with me on this one but I've spent enough of my time on this issue, its a brand new stove and I paid a pretty premium price

You're burn time is going to be drastically reduced because you reached overfire temperatures, like I said before. With such a strong draft, it sounds like you would benefit from taking the coals forward prior to re loading the stove. This technique should minimize the "inferno effect" and help you control the fire better. I'm going to say there is nothing wrong with your stove and Jotul is going to agree. Your local dealer doesn't sound all that great if he just handed you things to try instead of looking at the issue himself. Try taking the coals forward, loading, and knocking the air down a little earlier - I think this will help. Also, the coaling stage is considered "burn time". I'm heating my entire home with this stove, in NY, I think you can manage to heat a 500 sq ft room with it.
 
Last edited:
  • Like
Reactions: firefighterjake
Firstly, I think 70K BTU is max input, but that doesn't really matter. 35 lbs of wood is about 200,000 btu's x 65 percent eff of the appliance divided by time. Its not perfect, but it averages about 20-25000 btus output per hour over 8 hours. That should heat around 1500 sq ft nicely on a normal New England day. (30-35 deg daytime, 20's at night). Obviously its less sq footage with the super cold we have been having. The size room you described NE, the stove would I'd think handle fine. Again, these things happen, reasonable heads usually will get things worked out. Spewing unkind remarks about people or appliances might make you feel better, but doesn't drive the problem. Jotul historically is very proactive about resolving these things, or they are when they are involved with the process. Good luck.
 
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.


you're sucking air, combined with that very high chimney. You've got to pass the dollar bill test in order for your stove to work right (IMO)
 
  • Like
Reactions: RevJim708
Random thoughts . . .

Criss crossing the wood in the fire box will not lead to longer burn times . . . should have just the opposite effect.

Oak tends to burn much, much better with more heat and longer burns when seasoned . . . and generally . . . without a moisture meter . . . we're talking two to three years before it is primo wood.

Manufacturing defects happen . . . but if I was a betting man (I'm not by the way) . . . I would still guess this is not a problem with a defect.

The "dollar test" . . . is the dollar just slipping out with absolutely no resistance or does it come out but it feels as though it has a bit of resistance -- it doesn't have to be a grip of death to mean that the gaskets are no good . . . as long as there is some resistance.

Burn times . . . as mentioned . . . there are a lot variables . . . outside temp, insulation in the home, how the stove is run, when the air control is shut down . . . and the big one . . . our own definitions. Truthfully, I wouldn't say I've ever got a 9-hour burn time with my Oslo . . . I would say it's more like 4-5 hours of usable heat (active flames and coaling where the stove stays over 350-450 degrees). That said . . . I don't think this is the OP's issue as it sounds as if they're getting quite short burn times . . . to the point where there are not many coals even.

These stoves are pretty tough . . . tough enough to take a short foray into some high temps usually . . . I think I would be strongly considering this to be a draft issue and would perhaps bring the stove up to temp as quickly as possible, lower the air to the lowest setting where it is pumping out secondaries and if the fire is still going strong consider using some tin foil to experiment and see if partially blocking the incoming air has any effect on the heat and longer burns . . . if this has a positive change after a few fires . . . consider a damper in the flue . . . if not . . . back to looking for a culprit.

I know the front door latch can be adjusted . . . cannot remember if the side door can be adjusted.

Assuming the baffle board and insulation blanket are still in place and were not removed by the installer or slipped out of place during the transport from the stove to the hearth . . .

Air control lever . . . when the air control lever is turned down there is a very good chance the stove's temp will increase . . . and that's a good thing . . . less air coming into the stove means less heated air going up the chimney . . . more heat with the secondary burn, longer burn.
 
I would go with addressing each issue seperatly starting at the stove and working my way up. I would start with fixing the physical defect (door). Have the dealer/installer come out and while visibly looking at the stove tell you why the door isn't passing the test. Chimney hight would be next to tackle. If that doesnt work, then go to the theoretical btu's and get a different brand. But, all brand's btu's are somewhat sketchy figures at best. Have used, dutchwest, jotul, VC, nashua and hearthstone stoves and never really cared if it hit the exact btu number/ burn time was as long as it ran safe, heated the space to my liking and looked good.
 
Again the dollar bill just pulls through the door with NO resistance on that side door.

Again we tried larger gaskets, I say we in that they gave me the gasket and cement and were like knock yourself out

Again tried even a brand new door, worked worse
 
A lot of conflicting info. You've said you control it pretty well and temp doesn't go over 600 then you hit 700 and still climbing and can't control.

Not that there can't be times when both can happen but it would help to figure things if you could be clearer. So for example maybe on a cold start you can control but hot/warm reloads get out of control.

Jotuls are good stoves and many out there working well so I would try to get to the bottom of why yours is not acting as it should.

More or less only 4 things at work:
1. Stove
2. Chimney
3. Fuel
4. Operator

Could be a combo of the above. Take some pics of the unit in place and some good details of the install. 35' sounds like a lot of chimney. The forum will be able to get it sorted out if you want.
 
Exactly
The issue again is NOT about heat it's anout burn time being insufficient


if you have an air leak you will burn wood at a faster rate than a air tight stove would. Your strong draft will increase the effect of the air leak
 
if you have an air leak you will burn wood at a faster rate than a air tight stove would. Your strong draft will increase the effect of the air leak


Exactly! This is exactly what I think!

So the draft I can alter with the butterfly damper.

But what to do about the air leak that we can not seem to fix?
 
do u have a rope gasket on the door that is leaking?
 
I had a similar issue with my stove. I have a strong draft, and my front gasket leaked around the glass. I tried everything i could think of to fix it, and finally i just went to tractor supply and bought a small rope gasket to replace the flat gasket around the glass. I have had nothing but wood burning joy from my stove since.

Edit: so i would just buy a larger gasket and see if that fixes it, also when u install it be sure not to stretch it much. and make sure it is uniform in size all the way around the door
 
Last edited:

I had a similar issue with my stove. I have a strong draft, and my front gasket leaked around the glass. I tried everything i could think of to fix it, and finally i just went to tractor supply and bought a small rope gasket to replace the flat gasket around the glass. I have had nothing but wood burning joy from my stove since.
so i would just buy a larger gasket and see if that fixes it, also when u install it be sure not to stretch it much. and make sure it is uniform in size all the way around the door
 
I had a similar issue with my stove. I have a strong draft, and my front gasket leaked around the glass. I tried everything i could think of to fix it, and finally i just went to tractor supply and bought a small rope gasket to replace the flat gasket around the glass. I have had nothing but wood burning joy from my stove since.
so i would just buy a larger gasket and see if that fixes it, also when u install it be sure not to stretch it much. and make sure it is uniform in size all the way around the door

Thanks for that suggestion. I did try that already, didn't work, so I tried a larger gasket, applied it exactly as you say and still the same issue. No matter what I've tried including a new door it still leaks
 
is the stove possibly warped?