Any F 602 CB owners out there, how hot ya burning?

[nola mike]

Been chasing hot running on this thing this year. The cook plate at the hot part of the burn likes to hit just over 1K, with just behind that in the upper 800's, which lasts for 15-30 min. I've tried all different things to try to reduce air. Basically, the only thing that will lower it substantially is to close my flue damper completely. But then I get problems with the rest of the burn. I'm using the driest wood that I've had (15% oak) +/- liberty bricks (it doesn't matter if it's straight wood or mixed with bricks), so I'm not sure if that has something to do with it v. prior years. Anyway, wondering what temps the rest of you are running? I know they like to be hot, but this seems hotter than it should be. The flue temps immediately at the stove exit are low 500's; I'm guessing they'd be a lot lower 18" away, which seems reasonable.

 

[webby3650]

Check your glass. I bet you can move it up and down if you try..

 

[nola mike]

Check your glass. I bet you can move it up and down if you try..

Nope. Regasketed numerous times. I've got most of the air wash occluded. Fairly sure at this point that I'm not letting in more air than a new stock setup. Movement up and down of the glass shouldn't affect the amount of air allowed anyway, as near as I can tell.

 

[webby3650]

Nope. Regasketed numerous times. I've got most of the air wash occluded. Fairly sure at this point that I'm not letting in more air than a new stock setup. Movement up and down of the glass shouldn't affect the amount of air allowed anyway, as near as I can tell.

Well it certainly would if the glass is loose. Most of the ones is see have loose glass, it's not fully seated against the glass gasket. Unregulated air coming in around the glass would cause an overfire situation pretty quickly.

 

[nola mike]

Yeah, that's more of a back and forth looseness. Splitting hairs I guess, I know what you're getting at. That isn't it though, I replaced the gasket twice, first time with what the guys at the stove shop gave me, next with a thicker gasket that I had ordered online last year. I'm more curious on how other owners' stoves burn, to see if this is actually abnormal behavior. The stove is very peaky. The max temp doesn't seem dependent on when I shut the air, whether I do it in stages, etc. If I really try to limit it (closing early/closing damper fully) I can keep the peak temps down around 7-800, but I'm almost smoldering then, and will smolder at a much lower temp for the remainder of the burn.

 

[nola mike]

Well, don't know why it took me so long to find this. Rebuilt it last year and had the same issues. This year, fired it up and noticed a gap on the side, right at the front plate. And another one on the other side. They look so obvious, I can't believe I missed them before. Cemented them up, I'll light it tomorrow...hopefully that cures all my ills!

 

[wooduser]

When I was in my role as a gas appliance repairman, I was typically very observant.

When I was repairing other things such as bicycles, I could overlook stuff and later wonder how I'd missed something..

Common DIY experience, at least for me.

 

[begreen]

Well, don't know why it took me so long to find this. Rebuilt it last year and had the same issues. This year, fired it up and noticed a gap on the side, right at the front plate. And another one on the other side. They look so obvious, I can't believe I missed them before. Cemented them up, I'll light it tomorrow...hopefully that cures all my ills!

Is this the one you rebuilt? That leakage could make a big difference.

 

[nola mike]

Is this the one you rebuilt? That leakage could make a big difference.

Yeah, it's the one I rebuilt. The strange thing is I *looked hard* for a leak last year after the rebuild and didn't see one. In all fairness, the leak was only visible from certain angles, but still. IIRC I went around the seams with incense--but maybe I'm just thinking that that's what I should have done; I know I did it around the glass and doors. I finally managed to get it burning a little cooler by using the pipe damper, but never thought that that should be necessary. I'll let y'all know if this fixes it. I'll give it a good test with a bunch of bricks this weekend.

 

[begreen]

Did you cement all the seams when putting the pieces back together?

 

[nola mike]

Yes, but apparently not enough. used 1 or 2 small tubs

 

[nola mike]

Well, that helped until I noticed another leak around the door. Overfire before i noticed. New gasket, got a load in there now.

 

[nola mike]

Still running hot, though less so I think. Very dry oak + a bunch of liberty bricks might just be too much. I closed the pipe damper a bit, which brought it right under control. Didn't have to close it all the way; last year it was borderline even closed all the way. We'll see what happens when it gets colder and the draft increases

 

[nola mike]

Wow. So was still having problems. Didn't see any more obvious leaks, but when using a bellows to restart I noticed smoke puff out the back when I, uh, bellowed. The stove goes together tongue and groove style, and bolts together. When I reassembled, I slathered cement in the groove. However, I didn't pack it into the seams after it was together. Apparently that was a mistake. Not sure how much air was leaking into the combustion chamber v. into the exhaust, but I can't believe that I didn't appreciate it before. I cemented the seams, and it's a different stove. I have much more control now, and at least for the first few fires it's been noticeably less peaky. Same load as above (2 oak 4x4's and 7 liberty bricks), and it actually smoldered with the air all the way closed--that's about as much as I can pack the stove, and it doesn't get much drier than that. Eventually settled in at 800-850 griddle temp and 7-750 peak stovetop temp, which is just about perfect on this stove. I'm going to have to relearn this thing.

 

[begreen]

Normally a good bead of quality stove cement on the grooves before assembly works. There should be enough applied that it oozes inside and out. Finger trowel the inside ooze and also the outside ooze, then wipe around the outside joint clean. That worked for our stove reassembly.

 

[nola mike]

You'd think. Not sure what happened. There were definitely gaps outside, but they didn't look like they communicated. And who knows whether it was just one spot or more. Either way, it's probably good insurance to fill the gaps outside... Looks better too.

 

[nola mike]

So just an update, that was definitely the problem. Now with oak and no bricks I actually run it 1/4-1/2 open to get to 800 griddle temps. Huge difference, much more controllable now.

 

[nola mike]

Well, so that wasn't the end of the story. It was certainly better, but would still run hot. Hard to get under control once it got hot, and I was still using the key damper. While this thing has never been much for the secondary burn, it was at zero this year. I put compressed air through the secondary intake, and smoked around the inside to see where it was coming from. Sure enough, most was leaking around the manifold at the back. Little/no air making it to the front. Sooo...Took it apart yet again.

The manifold was warped and separated from the baffle (supposed to be sealed together to create the secondary air chamber).
The whole chamber wasn't sealed very well coming from the secondary air intake, allowing secondary air to bypass the chamber and enter the firebox directly.

My hypothesis is that the initial seam leakage led to a couple of pretty significant overfires, as well as just overall hot running. That warped the manifold, creating large gaps. I *think* that at that point I was getting a lot more secondary air than I should have. Instead of the pinholes on the manifold restricting air flow into the fire box, I now had essentially no flow restriction through the intake, which is about 6 x 3 cm.

So reassembled yet again, and the secondaries are now working again for the first time in years. Still not anything spectacular, but definitely there. It's running great now, but I've said that before
We'll see how it does once it gets cooler and starts pulling a serious draft...