Draft is too good...13NC

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delp

Member
Jan 6, 2009
186
pittsburgh, pa
Short of doing any major mechanical modifications requiring welding, etc., is there any way I might control my too-healthy draft?

Unfortunately, a pipe damper won't work either since I have the 13 tucked into the firebox with about 10" of head room before the adapter disappears up the flue connecting to the liner. I've got Roxul stuffed up the chimney and will (try) to fabricate a block-off plate this summer.

I've got 35+feet of liner and no cap as I left the old, clay chimney pots at the top of the chimney.

Just seems like I'm going through a ton of wood, even with the damper all the way in once things get up to speed.

Maybe it's just the way it is with the 13NC; thoughts?
 
What kind of stove top temps are you seeing with the air completely closed?

How long can you go on a full load w/ the air closed and still have enough hot coals to reload the stove from?

With that much chimney it certainly sounds like you are a candidate for having an excessive draft. The popular thing lately has been to limit the amount of air that the secondary air tubes can get by partially blocking it's intake opening (it's a rectangular opening on the shell of the stove above the primary air opening in the back).

If it's going to be a real pain for you to try and partially block this being where you have it installed, perhaps you could try blocking the dog house (the block that sticks up in the front of the stove and shoots air directly on the coals and sort of resembles a dog house) and air seeing if that gains you much. If you get down and look up at the front corners of your stove on the bottom, then you'll see a few openings that can be covered w/ a magnet. This will reduce the tertiary air to the stove (air to that doghouse I mentioned) and might provide you w/ benefit if you aren't seeing excessive stove top temps.

pen
 
Thanks, Pen. I'm going to need to re-read your response a couple of times and digest it to where I can answer with equally useful and intelligent info...i'll be back...
 
Pen I find your information real interesting. I to have to digest this.
 
does the 13 have the same holes as the 30? I can't check right now stoves a tad warm...
 
FireAnt said:
does the 13 have the same holes as the 30? I can't check right now stoves a tad warm...

My memory says yes, but that may be asking too much of it on a Fri.

pen
 
If the stove is on a pedestal you can't get to the front holes. They are right behind the front right and left leg mounts.
 
Thanks BB, yep, asked too much of it.

pen
 
Thanks! I have the legs.
 
Okay, I'm back with some answers to Pen's questions and comments.

Since the last post, I went through a full burn cycle, and here's what it was. Temp out today is 20º with no wind.

12:10 Stove 325º bed of coals, load with 6-7 med/small splits and one med 1/2 round at rear bottom
12:30 Stove 625º (or, right on the white to red zone line on the Condar "Inferno" thermo). At this point the draft is fully closed
12:45 Stove 700º with big secondaries -not supper dreamy/psychadelic ones but more like mini jets and mostly at the rear-most tube
1:10 Stove 590º
2:10 Stove 525º
3:10 Stove 350º - "phantom logs" at rear or stove. Or, logs burnt to coals that defy gravity and retain their form...Rake these apart and bring all coals to front in a heap around the house o'hound; open draft to squeeze a bit more heat and burn them down for reload.

So, I got about 3.5 hours burn, which seems lame.

Questions:

Is the intake opening for the secondaries on the interior of the firebox or outside the stove behind the built-in heat shield?

Any clever ways to block the dog house air, aluminum foil...or?

Since I have the pedestal, I can't access the other holes mentioned. Thanks, BrotherBart.

If it is what it is then so be it. One factor I can't comment on is wood species --I've now got generic Craigslist "mixed hardwood" and as a total noob, I have no idea what's what. It is dry, though, 12-17% MC on fresh split face. Perhaps not splitting to check moisture is the one thing I could do and have larger splits in the load.

Thanks for the help so far and any comments worth noting.
 
delp said:
Okay, I'm back with some answers to Pen's questions and comments.

Since the last post, I went through a full burn cycle, and here's what it was. Temp out today is 20º with no wind.

12:10 Stove 325º bed of coals, load with 6-7 med/small splits and one med 1/2 round at rear bottom
12:30 Stove 625º (or, right on the white to red zone line on the Condar "Inferno" thermo). At this point the draft is fully closed
12:45 Stove 700º with big secondaries -not supper dreamy/psychadelic ones but more like mini jets and mostly at the rear-most tube
1:10 Stove 590º
2:10 Stove 525º
3:10 Stove 350º - "phantom logs" at rear or stove. Or, logs burnt to coals that defy gravity and retain their form...Rake these apart and bring all coals to front in a heap around the house o'hound; open draft to squeeze a bit more heat and burn them down for reload.

So, I got about 3.5 hours burn, which seems lame.

Questions:

Is the intake opening for the secondaries on the interior of the firebox or outside the stove behind the built-in heat shield?

Any clever ways to block the dog house air, aluminum foil...or?

Since I have the pedestal, I can't access the other holes mentioned. Thanks, BrotherBart.

If it is what it is then so be it. One factor I can't comment on is wood species --I've now got generic Craigslist "mixed hardwood" and as a total noob, I have no idea what's what. It is dry, though, 12-17% MC on fresh split face. Perhaps not splitting to check moisture is the one thing I could do and have larger splits in the load.

Thanks for the help so far and any comments worth noting.
Delp..weigh out a load before you load..I'm curious as to how much you're getting into that stove.
I doubt you're getting much over 30 pounds.
30lbsx7000btu=210,000btu divided by 3.5 hours would be around 60,000 btu/hour....pretty high output..lets say it's 75% efficient..that would still leave 45,000 btu/hour of usable heat...decent enough.
 
The secondary air intake is a small hole in the back of the bottom of the firebox. If you want to try it without doghouse air just put an appropriate size bolt in the hole in the doghouse.
 
Thanks for the info, BrotherBart. I'll plat around and see if anything of note changes.

HotCoals, cool calculations! I'm definitely not packing the box as most probably do. First, I don't have a chain saw so I can't recut splits so I can loan NS, which I think would allow for more wood. As it is, there are for sure plenty of holes left when I load. I'll try to weigh a load this weekend.
 
delp said:
Okay, I'm back with some answers to Pen's questions and comments.

Since the last post, I went through a full burn cycle, and here's what it was. Temp out today is 20º with no wind.

12:10 Stove 325º bed of coals, load with 6-7 med/small splits and one med 1/2 round at rear bottom
12:30 Stove 625º (or, right on the white to red zone line on the Condar "Inferno" thermo). At this point the draft is fully closed
12:45 Stove 700º with big secondaries -not supper dreamy/psychadelic ones but more like mini jets and mostly at the rear-most tube
1:10 Stove 590º
2:10 Stove 525º
3:10 Stove 350º - "phantom logs" at rear or stove. Or, logs burnt to coals that defy gravity and retain their form...Rake these apart and bring all coals to front in a heap around the house o'hound; open draft to squeeze a bit more heat and burn them down for reload.

So, I got about 3.5 hours burn, which seems lame.

This is how my 13 runs. I have about 18' of chimney straight up. 4 hours of good decent heat is about it before a reload. Thats what I consider a "burn time".
 
HotCoals said:
delp said:
Okay, I'm back with some answers to Pen's questions and comments.

Since the last post, I went through a full burn cycle, and here's what it was. Temp out today is 20º with no wind.

12:10 Stove 325º bed of coals, load with 6-7 med/small splits and one med 1/2 round at rear bottom
12:30 Stove 625º (or, right on the white to red zone line on the Condar "Inferno" thermo). At this point the draft is fully closed
12:45 Stove 700º with big secondaries -not supper dreamy/psychadelic ones but more like mini jets and mostly at the rear-most tube
1:10 Stove 590º
2:10 Stove 525º
3:10 Stove 350º - "phantom logs" at rear or stove. Or, logs burnt to coals that defy gravity and retain their form...Rake these apart and bring all coals to front in a heap around the house o'hound; open draft to squeeze a bit more heat and burn them down for reload.

So, I got about 3.5 hours burn, which seems lame.

Questions:

Is the intake opening for the secondaries on the interior of the firebox or outside the stove behind the built-in heat shield?

Any clever ways to block the dog house air, aluminum foil...or?

Since I have the pedestal, I can't access the other holes mentioned. Thanks, BrotherBart.

If it is what it is then so be it. One factor I can't comment on is wood species --I've now got generic Craigslist "mixed hardwood" and as a total noob, I have no idea what's what. It is dry, though, 12-17% MC on fresh split face. Perhaps not splitting to check moisture is the one thing I could do and have larger splits in the load.

Thanks for the help so far and any comments worth noting.
Delp..weigh out a load before you load..I'm curious as to how much you're getting into that stove.
I doubt you're getting much over 30 pounds.
30lbsx7000btu=210,000btu divided by 3.5 hours would be around 60,000 btu/hour....pretty high output..lets say it's 75% efficient..that would still leave 45,000 btu/hour of usable heat...decent enough.

If I remember correctly, the 13 is rated at 55,000 BTU's so your numbers are darn close.
 
Were you closing the air down in stages up to 625 or was it wide open until then? By a 400 degree stove top I'd say you should be beginning to start turning things down if you aren't doing so already.

Sorry for my mistake on some of the earlier information on the locations of the secondary and tertiary air intakes. Thanks for the correct info BB. Of all the things I have lost, I miss my mind the most.

pen
 
delp said:
Thanks for the info, BrotherBart. I'll plat around and see if anything of note changes.

HotCoals, cool calculations! I'm definitely not packing the box as most probably do. First, I don't have a chain saw so I can't recut splits so I can loan NS, which I think would allow for more wood. As it is, there are for sure plenty of holes left when I load. I'll try to weigh a load this weekend.

The 13 loves N/S loads. I don't cut all my wood short enough for N/S, to much time and its a pain handling all those small pieces. I burn close to 50% of the time N/S.
 
Pen, Yes, I started (and always do) shutting down the air at around 375-400º by about a 1/4, 450º +/-, close down by 1/2 and anywhere from 500-600 I'm closed down the whole way. The decision is based not just on temp but on what the fire is doing too.

TrailRated -thanks for all the info! Looking forward to being able to load NS, if nothing else to at least see the difference. As it is, I have varying lengths and there are inevitable holes in the load...like a losing game of Tetris...

Well, it seems like draft or not, the 13 is doing what the 13 does --4hrs average burn/heat time. I'm excited to learn to ID the wood I'm burning too so I can appreciate the "good stuff," like black locust, hedge, etc.

Pen, I think that losing one's mind beats wasting one's mind. I think you're fine.

Thanks to all!
 
I have a tall chimney like yours (probably close to 40') with my stove being in the basement and if I'm not careful can end up with the same experience you described, which is basically that you're excessive draft is causing a very intense burn with secondaries blasting like flames out of a gas grill resulting a shorter than optimal burn times. The key for me is to base everything off of the flue temps rather than the stove top temps. If you don't have a thermometer on your stove pipe I would recommend you get a good one and place it 18" up on the pipe. In my experience the flue temp will rise much faster than the stove top temp and if I let the flue temp get too high too fast it will cause an inferno inside the stove. My technique is to start turning down the air supply based on where the flue temp is and how quickly it's getting there. By not letting it get too high too fast I avoid the intense secondaries that blast through the wood. It might take a little bit longer for the stove to come up to temp but you'll get a longer burn at prime temps rather than a shorter burn and higher temps.
 
Thanks for your thoughtful post, albertj03

Unfortunately, I can't really use a flue thermometer because the stove is set right into the old firebox, and I only have about 10" of exposed adapter before it disappears and joins the liner in the flue.

I don't suppose that an IR reading off the surface of that small (and too close to the stove top) adapter would give an accurate (or ballpark) flue temp...?
 
That would be better than guessing. Or you could install a remote reading electronic probe. That's a more expensive option, but has the benefit of adding a high temp alarm.
 
delp said:
Thanks for your thoughtful post, albertj03

Unfortunately, I can't really use a flue thermometer because the stove is set right into the old firebox, and I only have about 10" of exposed adapter before it disappears and joins the liner in the flue.

I don't suppose that an IR reading off the surface of that small (and too close to the stove top) adapter would give an accurate (or ballpark) flue temp...?

Duh! Sorry I missed that your stove pipe is not fully accessible. From your time-line it seems like your stove top temps are rising pretty quickly so you might just try cutting the air back a little sooner than you are now. Another thing you could do is install a damper in that 10" section of pipe to cut the draft down and extent the burn. I installed a Duravent damper this season and it's been a big help for when the stove wants to take off on me. The few times it's happened this season I've been able to close the damper and usually within a few minutes the flue temps will start to back off to an acceptable level.
 
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