Jotul Oslo F500 primary air

[MoparManLI]

I've had a Oslo for two seasons now. Very pleased with it EXCEPT for the primary air control. It doesn't seem let in enough air to get the stove really going with the door(s) closed - need to leave the side door cracked until it really, really gets going and secondary combustion takes off. If it dies back, crack a door and it picks right up. It's not a problem for me, but wife can't quite get the hang of it...

Chimmney is ~18' SS lined masonary, I inspected it (again) last week and it's clean and clear from top to bottom. Draft is excellent, can almost be too much if it gets windy out.

Stove has been like this since new. I've checked the passages under the primary air inlet and they're clean. Wondering if the 3, 1/4" holes in the primary air housing(inside the front door) are the restriction or if it's elsewere in the stove?

Is this a known "problem" with these stoves?

I burn mainly well seasoned Oak and Maple, some Locust.

 

[Corie]

Is that 18' of lined masonary outside of the house?


You seem to be describing two things that oppose each other. If the draft is good, the stove should run wonderfully with the doors closed.


It leads me to believe either the draft isn't as strong as you think, OR you have an internally defective stove.

 

[MountainStoveGuy]

you will always have to leave the door open to get the stove going. You cant close the door untill you have enought draft to pull air throught the stove. Secondary combustion will not work with any door open. How long is the horizontal before it goes verticle up the chimney? Is there a 1/4" of rise per foot on the horizontal run? is the Chimney exterior of the house? is the liner insulated?

 

[begreen]

Also, describe what you are using to get the fire going. What kind of wood, how large are the initial splits? I make sure that I always have on hand several boxes of cabinetry wood scraps to start a fire with. They make it easy to get a hot fire going quickly. New flooring scraps work great too. I also got some SuperCedars this year. With them, the fire just about lights itself. She's a happy camper now.

 

[MoparManLI]

Thanks for all the replys

Masonary chimmney is external, uninsulated SS liner all the way to the top. Horizontal run is about 18" long, and runs at a good angle (about 4" per foot)

The stove kicks up fast if a door is cracked, seems more like it's starved for air than not enough draft. I have never had any blowback or backdraft with this stove / chimney, never was a problem with the fireplace before the stove either.

I know it takes some time with the door open to get going - I usually don't close it until some of the kindling has coaled and everything on top of it is burning well.

I burn mainly oak that's been cut/split/covered for over a year. Kindling is mainly 3/4
x1" sticks of pine and oak hardwood floor scraps (new not used).

 

[MountainStoveGuy]

pull off the cover off the air port in the front and verify that it is free and clear of furnace cement. If that is free of cement or what ever, then you dont have a supply problem, you have a draft problem, or a unseasoned wood problem.. If your woodpile is coverd all over, then it might not be dry. It takes along time for oak to dry. To rule out the wood go to the grocery and buy a bundle of wood and try it. As far as starving air and draft, there both related. How long is the horizontal and does it rise 1/4" per foot?

 

[begreen]

Thanks for all the replys

Masonary chimmney is external, uninsulated SS liner all the way to the top.

The stove kicks up fast if a door is cracked, seems more like it's starved for air than not enough draft. I have never had any blowback or backdraft with this stove / chimney, never was a problem with the fireplace before the stove either.

I know it takes some time with the door open to get going - I usually don't close it until some of the kindling has coaled.

I burn mainly oak or maple that's been cut/split/covered for over a year. Kindling is mainly 3/4
x1" sticks of pine and oak hardwood floor scraps (new not used).

IMHO, Jotuls can be a bit stingy when providing startup air. Good stoves, but it would be nice to see a startup air detent or control on their bigger stoves. Get her a box of SuperCedars from Thomas. For a free sample email him at: [email protected]

 

[MoparManLI]

pull off the cover off the air port in the front and verify that it is free and clear of furnace cement.

I'll check it tonight if it cools down enough

If your woodpile is coverd all over, then it might not be dry.

Just covered on top to keep rain/snow off, sides open.

As far as starving air and draft, there both related. How long is the horizontal and does it rise 1/4" per foot?

Rise is in excess of 1/4" per ft - closer to 4" per foot. Horiz. run is about 18" long

 

[MountainStoveGuy]

sounds good then, definatly check that air port. there has been many, many Jotuls that have that partially blocked with cement. Its not uncommon and its worth a look. It takes a 10mm wrench.

 

[MountainStoveGuy]

and just to make sure, your startup should be something like this.
door open
few small splits, some kindling, and a firestarter of some sort (newspaper, supercedar, fatwood, etc)
Front air port should not be blocked with wood. You need to make a "cave" of wood around your airport.
Light off the starter and leave the door cracked (handle in closed position, latch resting against t he frame)
once the small splits light up you should be able to close the door, once the initial kindling/small split fire is coals, fill up the firebox with wood.

 

[MoparManLI]

That's exactly my startup.

If I have any short small splits I'll put them front to back between the primary air inlet to make an "air tunnel" under the kinding (if that makes sense)

 

[TreeCo]

You need to make a "cave" of wood around your airport.

This point bears repeating. With my Jotul F600cb it is very easy to lay a piece of wood in the stove that blocks the air port and it sure slows down start up.

It's also something to watch for when reloading. Sometimes I will place small blocks of wood on each side of the port and then put a piece on top of these smaller pieces..... the air from the port blows under this larger piece and often results in getting a nice secondary combustion burn going again quickly.

From what I'm hearing in this thread the culprit is likely wet wood but even if your wood is not optimal it pays to watch that airport.

 

[begreen]

Where does the air from the air port enter the firebox in the F500 and F600?

 

[MountainStoveGuy]

in the front, under that box, same as yours on the f400

 

[begreen]

Sounds like a good topic for a little wiki.

 

[HalJason]

Where does the air from the air port enter the firebox in the F500 and F600?

In the C450 inserts, there is a single air inlet in the rear, which splits into 2 channels. One runs under the firebox (I believe) and supplies primary air via the hump in the front. The other runs inside the firebox in the rear and enters the secondary manifold just above the firebricks in the rear of the firebox.

The C450 manual has a very good airflow diagram, for both combustion and convection air, so you may find an equally good diagram in the F500/F600 manuals.

-Hal

 

[KarynAnne]

Jotul Oslo owner here with the identical problem. The wood is fine, the draft is fine, the stove just seems starved for air on the reload. Especially if it's for the overnighter and you've got it packed. Without the side door open I could just forget it. I like the suggestion about the 2 blocks of wood on either side of the air, but I still think that my stove would still need the added air from the side door. However, if I reload while the stove is still hot, hot...(about 400), it does fine. But then I'm only putting in one or two splits depending on the size.

 

[Corie]

Well really, 400 degrees isn't "hot, hot". That's darn near the sweet spot. On a full load of wood and closed down for the night, my stove hovers around 500 degrees with very active secondary.


KaryAnne, what type of chimney do you have and where is located?

 

[KarynAnne]

Well really, 400 degrees isn't "hot, hot". That's darn near the sweet spot. On a full load of wood and closed down for the night, my stove hovers around 500 degrees with very active secondary.


KaryAnne, what type of chimney do you have and where is located?

Well, yes - you're right. Hot, hot would be about 600 - 650. I guess that I meant that if it's lower than 400 I may be in for a bit of a fight to get it really engaged again. Side door open, etc. At 400 I probably don't have to mess with the side door, but that's about the threshold temperature.

I have an external masonry chimney and my stove is in the basement. I wish that I could say that mine hovers around 500 with very active secondary all night, but it doesn't. To be honest, I don't really know what it does. But, the oil burner hasn't kicked on in months, so that's good. Usually I don't have sooty stove windows in the morning, so that's good too. I'd love to have an hourly log of what it's doing through the night. I ought to set up a psudo-overnight burn sometime during the day and log it. (Is that a little obsessive?)

 

[Corie]

With all due respect to both of you, it sounds like a lot of the problem is in the chimney system.

I could be wrong, because I am far from an expert, but even though you both have said that your chimneys draft well, you're both describing the conditions that a rapidly cooling external chimney would exhibit. It sounds to me in both cases that the stove is simply operating so efficiently that there just isn't enough heat escaping up the chimney to maintain a strong enough draft.

I could be wrong, and I don't mean to insult either one of you or your setups. But they are both less than ideal and BeGreen is burning the same stove with an all internal chimney and having non of the problems you're both talking about. Of course it is possible that there is an internal defect in both of your stoves. But to me, it sounds like a better chimney system is in order.

On my stove, which is obviously different than yours, I can get stove temperatures well about 600 degrees if the air control is left fully open. This stove is venting into an external Class A chimney though, which may be part of the difference.

 

[KarynAnne]

Maybe, but how could I find out? I don't have any problem at all with smoke puffing back though the side door, which is I guess what I'd expect if I had a chimney problem. Am I missing something? As I'm completely new to this I'd listen to any and all suggestions. I just thought that it was fairly common for Jotul users to experience this. Maybe not though.

 

[begreen]

Good analysis Corie. The chimney system is half the stove. I can easily revive the fire if there is a bed of glowing coals as long as I don't put too large a split on it at first. If the fire has died down, the trick is to put a bed of kindling or small splits down first, then the bigger splits. In about 30-45 minutes the fire will be raging again and then I can think about dampering down for the night.

 

[MoparManLI]

Front air port should not be blocked with wood. You need to make a "cave" of wood around your airport.

It was too cold tonight (5deg above, 20mph winds) to shut it down to check the primary air port, but I tried the above and WOW.

Dug a "trench" in the coals from air port to the firebrick, put in 2 pieces of oak and the top corner temp went from 300 to 600 in less than 15 minutes. Secondary combustion started in a few minutes.

Jotul ought to have something in the manual about this. I used to just clear a small area around the port, now I know better.

 

[begreen]

Yes I agree with you. Jotul needs to have a heads up, especially because this runs contrary to best practice in some other stoves where one rakes the coals forward before adding wood.

 

[MoparManLI]

I could be wrong, because I am far from an expert, but even though you both have said that your chimneys draft well, you're both describing the conditions that a rapidly cooling external chimney would exhibit. It sounds to me in both cases that the stove is simply operating so efficiently that there just isn't enough heat escaping up the chimney to maintain a strong enough draft.

For those that aren't having a problem mabye very strong draft is overcoming the primary air restriction

If there was a port for a manometer we could compare readings to see who's got what.