Oslo Not Maintaining High Temp For Normal Period of Time

[robalp]

Good day. I have a Jotul Oslo which I have loved over the last 6 or so years since I installed it. It is our primary heat source along with our Harmon Pellet stove on the other side of the house. Lately I don't seem to be maintaining the stove temps in the above 400 area for very long. I might get normal temps of 400 to 650 for an hour or so but then it settles back to 250ish with the air turned mostly down or even open half way. I am burning mostly oak split and stacked in my yard for minimum of 2 years (bark falls off every piece). I clean the Chimney at the start of every burning season and typically halfway through if there is no snow and I can get up there. I changed all of the gaskets before the start of last year so I don't think that could be an issue.

The only thing that seems like it might be an issue is the piece of insulation on the top of the stove above the plate got torn a bit during a cleaning last spring. Could that be the possible reason? It is still there, just in two pieces. Would not seem to me to be an issue but that is the only thing that has changed... I don't seem to get as much secondary burn as I think I should and again wonder if this is simply due to the insulation issue... Since I am not maintaining high temps and am getting a lot of coal buildup and have to run the air wide open to burn it down before reloading...

Any suggestions?

 

[moresnow]

Possibly be worth putting a moisture meter to a fresh re-split? Looking at your list of stoves would make one think you have a good handle on stove operation! I left 2 yr seasoned Oak in my back yard this fall as it was still mostly off the scale wet on my meter.

 

[robalp]

Possibly be worth putting a moisture meter to a fresh re-split? Looking at your list of stoves would make one think you have a good handle on stove operation! I left 2 yr seasoned Oak in my back yard this fall as it was still mostly off the scale wet on my meter.

Thanks for the reply.
Moisture is down below 17 percent on the pieces I checked. I have a pretty good stash (8 or so cords at all times) so I typically measure the different stacks as they dry differently due to where they end up in the yard. Some stacks take longer then others simply from more or less sun or wind. The stack I am burning was measured in the summer and then moved to the "wood shed" to stay dry back in early August. I will measure a fresh split tomorrow when I have a few pieces that have been in the house warming up for a while.

 

[begreen]

Is the split thickness the same as in previous years or are the splits a bit smaller this year?

 

[robalp]

Is the split thickness the same as in previous years or are the splits a bit smaller this year?

I typically have all sorts of sizes. More big then small I would say. I would not say any larger than previous seasons. When I measure, I would naturally look to larger splits to measure since they are "worse case" for each pile. I just brought in some large pieces and will split them tomorrow morning to check the content. I have found that its not very accurate to measure when the wood is super cold.

 

[Photog200]

On my Oslo, I change that insulation blanket at least every other year. At least on my stove, that blanket gets thinner over time and is not as effective. What tells me that it needs replacing is when the secondaries do not burn as well. You need that insulation to keep the heat in the chamber to make the hot air do the secondary combustion. I ordered a roll of it right off Amazon.com so I keep it on hand.

When burning at the temperatures you described, I get a ton of coaling as well, causing my temps drop too.. When I am burning below 400℉ the coals don't build up as much. I have been told that excessive moisture can also lead to coaling. My wood was stored in a greenhouse this summer and the moisture content was on average 12-15%. It sounds like you are in the proper range for moisture content so I would lean toward the problem being the insulation blanket. (at least for the reason of the secondaries not burning sufficiently)

 

[robalp]

On my Oslo, I change that insulation blanket at least every other year. At least on my stove, that blanket gets thinner over time and is not as effective. What tells me that it needs replacing is when the secondaries do not burn as well. You need that insulation to keep the heat in the chamber to make the hot air do the secondary combustion. I ordered a roll of it right off Amazon.com so I keep it on hand.

When burning at the temperatures you described, I get a ton of coaling as well, causing my temps drop too.. When I am burning below 400℉ the coals don't build up as much. I have been told that excessive moisture can also lead to coaling. My wood was stored in a greenhouse this summer and the moisture content was on average 12-15%. It sounds like you are in the proper range for moisture content so I would lean toward the problem being the insulation blanket. (at least for the reason of the secondaries not burning sufficiently)

Makes sense to me... I will see if I can find a roll and try it. That is the original insulating blanket that I never thought to change.
Thanks for your suggestion!

 

[XmasTreefarmer]

On my Oslo, I change that insulation blanket at least every other year. At least on my stove, that blanket gets thinner over time and is not as effective. What tells me that it needs replacing is when the secondaries do not burn as well. You need that insulation to keep the heat in the chamber to make the hot air do the secondary combustion. I ordered a roll of it right off Amazon.com so I keep it on hand.

When burning at the temperatures you described, I get a ton of coaling as well, causing my temps drop too.. When I am burning below 400℉ the coals don't build up as much. I have been told that excessive moisture can also lead to coaling. My wood was stored in a greenhouse this summer and the moisture content was on average 12-15%. It sounds like you are in the proper range for moisture content so I would lean toward the problem being the insulation blanket. (at least for the reason of the secondaries not burning sufficiently)

Photog200 - What thickness and size insulation are you using? I see that Amazon has different thicknesses and sizes - individual sheets and rolls as you mentioned. Thanks. I don't have an Oslo yet, but plan on replacing my old and ailing VC Defiant in Spring and am busy learning all I can about the stove.

 

[Photog200]

The roll I got from my Jøtul dealer was 13" wide, 4' long by 1" thick. You then cut that piece off the roll to the width of that top shelf. The new roll I got off Amazon was much larger and I will just cut it to size needed. Just make sure you get the 1" thick stuff, if you go thicker, that is not what Jøtul called for and might hold in too much heat.

Hope this helps

 

[robalp]

Re-split 4 splits today. Had moisture content ranging from 16.3 to 19.6 so I am pretty satisfied that the wood is mostly dry enough. I picked up a few Bio Blocks today (compressed wood product) and new piece of insulating blanket. Just loaded some in the stove. Gonna wait on the insulating blanket till next big clean out since I don't want to cool stove completely (though today is the first warm day in weeks). I have never tried the bio blocks but have heard good things. Wood Heat in Flemington NJ sells for 4 bucks or 3 if you buy a ton. Thinking it might be fun to mix with some wood to see if it makes any difference. I just loaded up so will post the results...
The insulation was about 20 bucks for a 2ft. piece.

 

[Photog200]

That price sound about right. Here is a link to what I bought last Sept. on Amazon. I will probably get 2 blankets out of it. and it is about $40.00

https://www.amazon.com/dp/B01H2RQYBW/?tag=hearthamazon-20.

 

[XmasTreefarmer]

The roll I got from my Jøtul dealer was 13" wide, 4' long by 1" thick. You then cut that piece off the roll to the width of that top shelf. The new roll I got off Amazon was much larger and I will just cut it to size needed. Just make sure you get the 1" thick stuff, if you go thicker, that is not what Jøtul called for and might hold in too much heat.

Hope this helps

Thanks, just what I needed. And thanks for sharing all of your experience with the Jotul Oslo as you transition to the Woodstock Progress Hybrid.

 

[Simonkenton]

photog200: I followed your link, and bought that blanket off of Amazon.
Now, please tell me how to change it on the Oslo.

 

[Photog200]

photog200: I followed your link, and bought that blanket off of Amazon.
Now, please tell me how to change it on the Oslo.

The top cover plate comes right off the stove. You can then see where the blanket sits right on top of the roof of the secondary burn chamber. You cut the insulation to the size to cover just the top of that secondary burn chamber roof. Make sure you put it to just the edge of the front of it so you do not block the flue path coming up from the fire. Also don't go too far to the back where you might block off the flue path where it goes into the flue collar. It really is a simple project and only takes about 15 minutes, including the time to vacuum everything out.

 

[Simonkenton]

Well, I just tried to lift the cover plate off. I am 6-3 and 220 and I am not a sissie.
I gave a pretty good lift on it, it felt like if I gave it much more horsepower I was going to lift the corner of that stove off the hearth.
It didn't budge. What do you think?

Is the stove pipe supposed to be removed to lift the cover plate.

 

[Photog200]

Hmmm, I replaced the original cover plate with the cooking plate right after I bought it. I am trying to remember if they had the original one bolted down. You can reach your hand up through the front to see if it is indeed bolted down. I know I can just open the front door and there is enough space where I can put my hand right up through where the flue gasses go. I have never removed the stove pipe to get at that cover plate.

Edit: We are talking about that small oval cover plate in the center of the top right? I just went out to the garage to look at the original cover plate. It does have bolt threaded holes on the back where it looks like it was bolted in with clips.

 

[XmasTreefarmer]

Well, I just tried to lift the cover plate off. I am 6-3 and 220 and I am not a sissie.
I gave a pretty good lift on it, it felt like if I gave it much more horsepower I was going to lift the corner of that stove off the hearth.
It didn't budge. What do you think?

Is the stove pipe supposed to be removed to lift the cover plate.

According to the Owners Manual - There are two tabs that hold the top plate in. You loosen the two bolts, swing the tabs out and it should lift out. If you don't have your Owners Manual handy it's on the Jotul site to download. Go to the Jotul 500 and then the Documentation section and you'll see the manual there and an Exploded View diagram.

 

[ratsrepus]

I also have the Oslo (f-500). On about the 8th or 9th year, its done a good job, or so I thought so until I got a blaze king princess in an comparable sq ft building. Been burning for longer than most and have had my fair share of wood stoves. I realized how much wood it eats compared to the bk.

 

[firefighterjake]

Well, I just tried to lift the cover plate off. I am 6-3 and 220 and I am not a sissie.
I gave a pretty good lift on it, it felt like if I gave it much more horsepower I was going to lift the corner of that stove off the hearth.
It didn't budge. What do you think?

Is the stove pipe supposed to be removed to lift the cover plate.

Two bolts . . . 10 mm I believe . . . for the oval center plate. Access via the front door . . . it can be a tight fit for large hands though. I tend to keep the bolts on the loose side -- hand tight at most so I can easily remove the oval center plate when I clean above the baffle each year . . . or replace the insulation blanket.

 

[Simonkenton]

Well, ratsrepus I am interested in what you say. I have been burning wood stoves since 1971 and I am astonished at how much wood the Oslo eats up.
Otherwise I love this stove.
I get a little more money on board I may have to give a look at the Blaze King.

Oops I just looked at a pic of a BK Princess. That is a no-go. I have a log cabin that is 2 years old, but looks like 200 years old. The Princess is too modern looking the fiancee would kill me if I tried to install that stove. Just wouldn't work in my house.

 

[begreen]

Oops I just looked at a pic of a BK Princess. That is a no-go. I have a log cabin that is 2 years old, but looks like 200 years old. The Princess is too modern looking the fiancee would kill me if I tried to install that stove. Just wouldn't work in my house.

That's why the Ashford line has been a success. The Princess is not royally pretty.

 

[ratsrepus]

does the ashford in your opinion perform as well? I just checked it out and it looks like a cast stove not steel like the princess.

 

[begreen]

does the ashford in your opinion perform as well? I just checked it out and it looks like a cast stove not steel like the princess.

As well as the Oslo? That depends on what one is looking for. The Ashford comes in two sizes. The larger Ashford 30.1 has a larger fuel capacity. It is a catalytic stove, so a bit more complex, but it's particularly good at miserly fuel consumption during milder weather. The Ashford is constructed quite differently from the Oslo. It is more like the F55 in design in that it is a steel stove with a cast iron jacket. Also like the F55 the Ashfords are front loaders. The cast iron jacket makes it less radiant than the Oslo, but with greater thermal mass and closer clearances. The Oslo will provide more BTUs when pushed, but the Ashford is thermostatically regulated. This regulation together with the heat soaking cast iron jacket help keep room temperature more even. They're both good stoves, but quite different in design. The Oslo has exceptional good, classic looks and is available in blue black enamel. The Ashford is also good looking, but more like the F55 again. It has enamel finishes available but not in the blue black that Jotul offers. The cook top is also different. The Oslo is direct contact where the Ashford has a convective top that has to be lifted off to have direct contact with the stove top. Not a big deal unless you cook or boil water a lot on the stove top. The Ashford can load N/S or E/W, where the Oslo is mostly an E/W loader.

Note, I have not owned either of these stoves. We wanted to put in an Oslo but our corner install would not allow the left side door loading so we got the Castine instead.

 

[sutphenj]

"Also like the F55 the Ashfords are front loaders. That makes it less radiant than the Oslo, but with greater thermal mass and closer clearances."

Isn't the Oslo a side and front loader? Curious on the thoughts/rationale behind front loaders being less radiant?

 

[begreen]

"Also like the F55 the Ashfords are front loaders. That makes it less radiant than the Oslo, but with greater thermal mass and closer clearances."

Isn't the Oslo a side and front loader? Curious on the thoughts/rationale behind front loaders being less radiant?

Bad phrasing on my part, thanks for catching that. I fixed it. Yes, the Oslo and F600 are front and side loaders while the F55 and Ashfords are strictly front loaders. Front loaders are not inherently less radiant. Cast iron jacketed stoves are less radiant than cast iron only stoves like the F600. F500, F400 etc. The cast iron jacket acts like a big heat shield that soaks up the heat into the mass of the cast iron jacket. This heat gets slowly released back into the room as the fire dies down.