Jøtul F45 V2 burn times (short) vs. runaway fires

[Upnort]

It seems I really need to shut the stove down sooner but it also seems the risk of doing that smokes me out a bit until it gets up to optimum temp. No fun, especially with mild asthma. I have the two boost holes plugged with random screws that seem to at least cover the hole openings. I haven't filled the stove full because I fear a massive overfiring temp. But I'd also like to get the longer burns and to limit opening the door to just reloads that make those longer burns possible. Also can someone tell/show me a picture of what the Exhaust Deflector looks like on their stove? Is it visible? Because I can't seem to locate mine.

 

[Todd]

It seems I really need to shut the stove down sooner but it also seems the risk of doing that smokes me out a bit until it gets up to optimum temp. No fun, especially with mild asthma. I have the two boost holes plugged with random screws that seem to at least cover the hole openings. I haven't filled the stove full because I fear a massive overfiring temp. But I'd also like to get the longer burns and to limit opening the door to just reloads that make those longer burns possible. Also can someone tell/show me a picture of what the Exhaust Deflector looks like on their stove? Is it visible? Because I can't seem to locate mine.

It’s going to take some trial and error learning your stove. Are you monitoring flue temps? That’s mostly how I judge when to turn the air down. I have a Condar flue probe about 20” above the flue collar.

When I get a fresh load reloaded I burn full air until I see the my thermometer start to rise and I usually cut it back to half air as it climbs into the orange zone or about 400. Then I leave at half air until the temp is in the mid orange range or 500-600 then I adjust the air down further to either a medium low setting or fully shut. There can be a short lag time when doing this and the flames may seem to die a bit before coming back but if you have good dry wood it shouldn’t stall on you.

The exhaust deflector is located at the front top above the glass in front of the baffle. You can stick your hand up there and feel it. It’s kind a just loosely sitting there and I’m not sure exactly what it does, maybe for the glass air wash? Here’s a bad pic of my top off, you can see the metal bar in front of the turbulators, I think that’s the exhaust deflector.

 

[Crab]

This is a pic from a post in another F45 thread. He had pulled off the top so you would be looking down on the stove top. That piece of angle is the exhaust deflector, it hangs from pins that are located above the door. When your stove is cold take a look up there from inside the stove or just feel for it. When I got my F45 home years ago, I did not notice that the deflector was not hung, similar to this pic, it was just laying there and it was blocking the exhaust flow. Eventually I hung it on the studs, my draft increased dramatically. I never have any smoke in the house from my V1 F45. Never open the door for extra draft. I have 22' from stove top to cap one 90 plus the 90 of the tee. Double wall stove pipe and 20' of Olympia Armor/Heavy flex insulated liner.

 

[Upnort]

It’s going to take some trial and error learning your stove. Are you monitoring flue temps? That’s mostly how I judge when to turn the air down. I have a Condar flue probe about 20” above the flue collar.

When I get a fresh load reloaded I burn full air until I see the my thermometer start to rise and I usually cut it back to half air as it climbs into the orange zone or about 400. Then I leave at half air until the temp is in the mid orange range or 500-600 then I adjust the air down further to either a medium low setting or fully shut. There can be a short lag time when doing this and the flames may seem to die a bit before coming back but if you have good dry wood it shouldn’t stall on you.

The exhaust deflector is located at the front top above the glass in front of the baffle. You can stick your hand up there and feel it. It’s kind a just loosely sitting there and I’m not sure exactly what it does, maybe for the glass air wash? Here’s a bad pic of my top off, you can see the metal bar in front of the turbulators, I think that’s the exhaust deflector.

Thank you both! The stove's been running, so I haven't had a chance to look for the exhaust deflector, but I will next time it is cold.

I'm still having issues with the stove climbing beyond 650° most of the time and today it got above 700°. However I have not stocked it full yet because I guess I fear hotter temps and overfiring. When it gets to the hot temps, it sometimes doesn't stay long, but it does eat through the wood. I know I am still learning the stove, but one thing I notice is that shutting down the air from 3/4s closed to fully closed doesn't seem to have any change. It's almost like the setting for 3/4 closed is really as closed as it gets and the rest is just display-sliding, because when I try closing it down past 3/4s and all the way, there is no effect on the flame, which almost always seems to be a bit too strong considering the air that is supposed to be cut off.

I did place two #8 sized screws in the boost holes. Maybe I need bigger ones.

I'd love to have more control of this stove. I do enjoy it. Except I do seem to have an exhaust issue even though I'm doing everything as I should be regarding preventing smoke from coming into the living space, and my chimney is also as it should be. Wood is dry. So that's why I'm also wondering about that exhaust deflector. Also I do try shutting down the stove sooner than 400STT to try to control the swift climbs over 650°, and sometimes that can cause a smoke smell for a bit. That might be more of the cause than anything but still.

I only have stove top thermometers, but if it means anything, I do have two of them! I have a double-walled pipe from stove to chimney. I don't have tools to install a probe thermometer. (I know I could probably get some but other purchases tend to come first.) Jotul suggests a ST thermometer in their manual, so they must have some use, right?

 

[Upnort]

It’s going to take some trial and error learning your stove. Are you monitoring flue When I get a fresh load reloaded I burn full air until I see the my thermometer start to rise and I usually cut it back to half air as it climbs into the orange zone or about 400. Then I leave at half air until the temp is in the mid orange range or 500-600 then I adjust the air down further to either a medium low setting or fully shut. There can be a short lag time when doing this and the flames may seem to die a bit before coming back but if you have good dry wood it shouldn’t stall on you.

Circling back to this: it doesn't seem like I have the control with my air that you have. Could the air control shutter be loose? It really makes minimal difference when I slide it. The most noticeable difference might be from fully open to 1/4 closed, but after that it doesn't seem to really slow the air down that much. And even then. The little plate that slides over when you close the lever isn't that tight. Is it supposed to be? It sort of just rests there. The lever does move it open/close, but it's a pretty easy slide. (My door gasket is tight and I don't think I need to remove a shim plate yet.)

 

[Todd]

My air slide does that too. If you move it to about 3/4 it’s really fully shut. If you lay down and look underneath you can see the two square holes that the air slide covers. You can also access the primary air mechanism through the dog house. There’s a cover plate with two bolts you remove. When your stove cools down I’d check that and feel for that exhaust deflector while your at it.

 

[Upnort]

Thank you! Regarding putting two bolts or screws in those boost holes to help slow down that air, because those screw/bolts fit their loosely, wouldn't they just get lifted up slightly when that primary air comes through? Because it seems like that primary air comes through with a little bit of force and at least enough to lift up a light loose screw? Unless I am misunderstanding this, which is very likely. Thanks again. You've all been so extremely helpful!

 

[Todd]

I don’t think there’s enough force to lift those screws up but you can also block them from underneath but it’s a little harder to get at.

When I was first experimenting with this I jammed some folded up aluminum foil between those holes and the bottom heat shield to block that air. Then I later thought of the screw idea.

 

[Upnort]

Thank you. It really seems like I don't have much control over the fire. I can't wait for the stove to reach 400°, shut it down a bit, wait for it to reach 500°, shut it down a bit more. It always climbs to over 650° STT and burns don't last that long if I wait much beyond 400° to start closing and even then the stove will always go above 650°. I am only filling it about half full because at this point, I don't want an inferno that won't calm down. I'm burning mostly birch and ash and some maple and oak, but mostly the first three. My fire closed down all the way is still crazy strong. No lazy flames and never any concern the fire will go out if I shut it down too soon. On fresh starts I wait until it gets near 400° before shutting down fully (no waiting in between numbers; if I wait, it roars), but if I wait that long on a reload, the fire just keeps climbing (it keeps climbing no matter what until it's burned thru the fuel). It really seems like the slide control doesn't do anything more once I have it half closed. From half to fully closed has the same effect, which is very little difference on the fire. It's very frustrating. And sometimes it does get a bit smoky when I do shut it down sooner, but it's either that or the high temperatures (even tho it seems like no matter what this stove wants to and will climb above 650° STT). Attaching a photo with the air all the way closed. This is about four good sized splits. Nearing 700° and I can't do anything about it. It does seem to go down after that. Is that just standard? I'd like a whole night burn but I'm not willing to risk an inferno if the temps just keep rising if adding that much wood will have that effect.

 

[Todd]

Have you been able to check your air control mechanism? Maybe it is loose and just needs to be tightened up? If you lay down and look up under there you should be able to tell if the slide is closing properly.