Jotul Oslo F500 V3 - Automatic secondary air setting

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New Member
Jan 22, 2024
We purchased this stove a few months ago and it has worked great. The last few weeks, it sometimes is hard to get up to temp. The side thermometer seems to have a hard time going above 600 degrees. When we do get it going really good, it will go up from there. My wood is in the 12 to 20 percent range. Should be plenty good.

My main question is about the automatic bypass. Is the door located behind the shield supposed to be fully open or fully closed when up in the 600 degree range? Mine is closed and the cable is loose. My ignorance led me to believe it should wind up tighter instead of getting loose when fired to operating temps. Perhaps my thinking is backwards.

Meanwhile, it's cold outside and I really don't want to shut this down to figure out the operation. Thanks for any info on this function of this stove.
When’s the last time you cleaned the catalyst? Could be getting clogged with ash.
Thanks for the reply Todd. An hour or so before my post, I checked and there was pretty much nothing on the surface of the cat. I pulled out my air compressor and gave it a few short blasts to clean it a bit more inside. One person mentioned the set screw on theirs was loose, so the cable wasn't moving. They didn't get a clear response, or not for OCD me. I don't think I have a home vacuum situation, as when I crack open the side door the stove rarely smokes, but immediately starts to burn really great. I figured I would try to learn about the bypass door so I could rule that out if it is working properly. Also, I guess this is the bypass door. The cable runs to it inside the back cover. The door appears to be sheet metal. At 600 degrees inside burn temp, the cable is really loose.

Again, thanks so much. There are a lot of variables.
The only time I've had a problem with mine not wanting to get back up to temp after adding more wood was when the four air outlet holes in the doghouse were blocked by ashes. I learned to scrape the ashes away from that area whenever I add more wood.
The only time I've had a problem with mine not wanting to get back up to temp after adding more wood was when the four air outlet holes in the doghouse were blocked by ashes. I learned to scrape the ashes away from that area whenever I add more wood.
That's what i do too in the F400.
I bet that is my exact problem. It was cold and we had a fairly deep layer of ash topped by 2 or 3" of red coals.

Is the doghouse area the bulge just behind the air adjustment lever? It still has a lot of red coals going so I can't really see the bottom at all.

The air intake has been a mystery to me. I saw where folks were talking about the incoming air blowing down over the glass, so I assumed the air came in from the top. Doh! This morning I was down to maybe an inch of red coals, so I was able to rake it a bit. Today it ran great. I believe this will solve my ignorance on the issue.

Thanks a ton!
Section 5 of the manual explains how the primary and secondary air inlets work in-depth. Figure 11 is a drawing of both air flows within the stove.

I've included a link to the manual below.

Operation Manual
Yes the Dog house is on the inside of the front middle of the firebox. Right below the door. It provides "Boost Air" to the bottom of the fire. It's not an air intake but an air supply to the front of the fire. It's air does come from the air intake though.
After reading the friendly manual again, studying some figures, I think I finally understand the air inlets into the firebox. I think I'm seeing air manifolds running up inside the front corners from the parts list and the air flow figures. And it looks like there are two panels where the grate goes, forming a manifold where air can be contained as it passes back to front going past the grate on each side. None of this is obvious when looking at the stove.

I had a really nice set of wood stove tools from the 80s. I can't find my rake anywhere. :( I need to make one. I've been using the hook on the poker to shuffle the ash and coals. A rake would help a ton. I have been doing this from the side. I'm not sure I can get that bottom front vent cleared as well as I should. I'm also going stop adding wood any time the coals build up to 3 or 4". Again, blocking that lower front inlet.

Thanks folks. This has been a bit frustrating.
What is the state of the flap/cable when the stove is cold?
The answer to that might take a while. The stove has not been cold for a couple of months and might not be cold for a while, depending on the weather. It is supposed to warm up tomorrow. Maybe I can let the fire die.
From totally cooled down to room temp, took a day... the cable in the back has an arch to it. Totally loose and hangs down maybe an inch of curvature. When it is up to an internal temp of 1000 degrees, the cable gets a bit taught, but is not enough to open the door located center-back-bottom behind the shielding. It doesn't move that door at all.

One person mentioned the set screw was loose on his and was asking how to 'clock' it before tightening. I can't see that mine is loose, but I haven't removed the cover. Mostly I would like to know if this door should open at operating temps.... like 600 degrees and above. We only have the internal thermometer. We should get a stove top one, but just haven't done it yet.

Meanwhile, I vacuumed out the stove including the 3 holes behind the air adjustment lever. I'm getting a much better idea of how this thing works. :)

I should mention this is a new stove. We purchased it in late September and installed in early October.
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@webby3650 have you observed the action of the secondary flapper on your stove? Is there a Jotul tech bulletin on setting this up?
First I’ve heard of this happening. Mine has about an inch of slack when cold. In very short order, the door is wide open when I run it.
After standing on my head for a bit, at 400-450 the door is barely showing a crack at the bottom corner. At 600 to 650, it's up to about 1/2". At 800, it's opened to around an inch on the end opposite the bimetal device, I suppose about as far open as would be needed. I suppose mine is operating as it should. The cable looseness when cool seemed odd or a bit alarming to me.

Thanks a ton, or should I say thanks a cord?