Is a disc damper worth installing?

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Dec 8, 2007
55
Chesepeake Bay
I've had ongoing problems getting my Jotul 3 cb to burn anthing above 500 degrees stove-top and I and the stove work hard to get it there, and I rarely, if ever, get secondary burn. I've tried many remedies and gotten all kinds of advice. My stove pipe is double walled six inch and goes straight up the interior about 20 feet to a cathedral ceiling and continues straight through the roof, a pretty powerful draft. The most consistant advice I get is that I'm losing all my heat up the chimney due to the strong draw and that an in-line disc damper would help keep the heat in the stove. First of all, does that sound right and worth the effort? And secondly, can I install a standard six-inch cast-iron disc damper in a six inch double-lined stove pipe? Are they compatible? What do you think before I start tearing things apart? Advice here always welcome and always helpful.
 
I just started burning my F3 this season, and I will say it cruises nicely just about 500* with the primary air closed down all the way and the secondaries are running full tilt. I would think that with your set up, you should have no issue at all hitting 500. I put a key damper on the snout going into my tee when I had my F-100 running, as I thought I was losing heat up the flue. I am still figuring the learning curve, before I start messing with the key damper. I would think that if you had a hard time controlling the fire and it was at a point of running away from you, a damper would be required.

How is your wood situation? I found that the stove likes well seasoned wood. It is actually surprisingly simple to reach cruising temp on a few small splits. If your draft is good, what does the wood look like when it is running? Is is slow to catch and smouldering? You can always buy a bundle of kiln-dried wood from a supermarket, or cut up pallets (be careful, as they pack a punch once going), and see if it runs better. There will be more here posting to help figure it out.

I am going to stay away from the pipe questions as I have a flex liner and not much experience with double wall.
 
My first question is how do you run it? Meaning full load, air open then what ????......... Perhaps it is not really the draft (it certainly could be) but just the learning curve.

Shawn
 
I get my wood from a reputable wood guy. It's mixed, but there is some good oak in it. He has though, been encouraging me to pry open my wallet and get all oak and says that will solve my problem plus I'd go through less than the 3 cords I burn a year. I start my stove with a few small splits, get it going adding larger pieces as I go along, pretty much until it is full., about three good sized 16-17" splits in a stove this size. I burn wide open, get it to max, about 550 on a good day and then damp the intake back about half way or a bit lower and let it cruise until the stove-top temp. falls below 350, which, sadly doesn't seem to take very long-maybe an hour then continue to feed the beast as needed. Of course this varies with the weather but that's my typical routine on an average winter day. At 350 or below my stove (admittedly a bit too small for the house, 1,900 Sq ft. and an "open" floor plan, which I thought would be a good thing in allowing air to curculate, now I'm not so sure) just can't keep up.
Not ready for the expense or hassle(think loving wife) of a larger stove right now so I'm trying to optimize the performance of this one. My fourth year with this stove in new house. Burned wood in previous house for 20 years, no problem.
 
Englishteacher said:
I get my wood from a reputable wood guy. It's mixed, but there is some good oak in it. He has though, been encouraging me to pry open my wallet and get all oak and says that will solve my problem plus I'd go through less than the 3 cords I burn a year. I start my stove with a few small splits, get it going adding larger pieces as I go along, pretty much until it is full., about three good sized 16-17" splits in a stove this size. I burn wide open, get it to max, about 550 on a good day and then damp the intake back about half way or a bit lower and let it cruise until the stove-top temp. falls below 350, which, sadly doesn't seem to take very long-maybe an hour then continue to feed the beast as needed. Of course this varies with the weather but that's my typical routine on an average winter day. At 350 or below my stove (admittedly a bit too small for the house, 1,900 Sq ft. and an "open" floor plan, which I thought would be a good thing in allowing air to circulate, now I'm not so sure) just can't keep up.
Not ready for the expense or hassle(think loving wife) of a larger stove right now so I'm trying to optimize the performance of this one. My fourth year with this stove in new house. Burned wood in previous house for 20 years, no problem.

I do not have this stove but..... it is a secondary burn model so I can speak to that.

First off, you say you got your wood from a reputable dealer. This immediately raises the question is it seasoned? I know the dealer said it was, but that means nothing. I would venture to say 95% of wood dealers call wood seasoned when it isn't. But lets assume that the fuel is properly seasoned...which I doubt....

You burn wide open until it reaches 550 !!!???!!!! That is definitely a problem. With properly seasoned wood, you most likely are sending a ton of heat up the flue that you shouldn't be. Try adjusting the damper back in stages, leave it open until the wood is charred and flaming well, say 20 mins or so, then push back the air 1/3.... wait about 10 minutes for the flames and secondaries to stabilize (keep your eye on the thermo)... then knock it back another 1/3..... wait another 10 minutes then almost all the way back. By doing this you should get much longer and cleaner burns. Todays stoves are designed to use a secondary burn of the gasses of the wood, by leaving it open as long as you are you are letting those gasses escape without being burned.

This is being discussed on another thread... https://www.hearth.com/econtent/index.php/forums/viewthread/82655/

The manufacturer says this unit has a 7 hour burn time... Usually these times are optimistic since they are done under "ideal" conditions. You should though get far longer than an hour while in cruise mode.

I am sure someone here with this specific stove will chime in soon.

There is a a learning curve with a new stove. I am wondering what you were burning in for the 20 years. I would guess either an old stove or an open fireplace?

Don't get frustrated, stay on this forum and ask whatever questions you have. This is a great group of people here, always willing to help.

Shawn
 
Try shutting down the stove earlier and in stages. With that amount of flue, at 400F you should be able to shut it down half-way or until the flames get lazy, but not out. Then, in about 10 minutes, as the fire regains vigor, close it down some more until the flames get lazy. With good dry wood, you should be able to close it down all the way at this point and the stove top temp will climb to around 550-650F. Also, be sure that the little, round-dial, start-up air control on the door front is fully closed.
 
Let me see If I'm getting it.

With a newer secondary-burn stove "burn cycles" are an important key to stove efficiency.

The least efficient method of burning being: burn as much wood that will fit wide open, get quick but short-lasting interior heat wasting both wood and heat.

The air intake is not a hot/cold dial on a refrigoator but a tool to be used to facilitate the most efficent burn cycle and that(counterintuitively to me at least) turning down the air intake at the right times in the cycle actually creates a hotter stove and fire not a cooler one.

Assuming a consistant quality of wood, and that one attends the air intake properly, in an efficent burn cycle what actually effects the heat is not how open or closed the intake is but merely how much fuel was/is in the stove.

Am I getting this?
 
Englishteacher said:
Let me see If I'm getting it.

With a newer secondary-burn stove "burn cycles" are an important key to stove efficiency.

The least efficient method of burning being: burn as much wood that will fit wide open, get quick but short-lasting interior heat wasting both wood and heat.

The air intake is not a hot/cold dial on a refrigoator but a tool to be used to facilitate the most efficent burn cycle and that(counterintuitively to me at least) turning down the air intake at the right times in the cycle actually creates a hotter stove and fire not a cooler one.

Assuming a consistant quality of wood, and that one attends the air intake properly, in an efficent burn cycle what actually effects the heat is not how open or closed the intake is but merely how much fuel was/is in the stove.

Am I getting this?

Yes, I think you are on the right direction. I had one of these stoves at my old house (loved the stove) and I recall that the 3CB has 2 air controls, correct? (For some reason I remember a slid at the bottom from left to right, but isn't there also one on the door?

As other have said, gradually shut down the air....I have a small insert with a small firebox, and around this time of year I use small splits and start shutting the air down gradually once the stove hits 375-400....I say gradually, and then it levels off around 500 or so.

Also, you are in a relatively milder climate, so even though the F3cb might be a little small for the house, I would stick with it as its a great little heater. (Really loved the one in our old house)
 
If that oak you are burning isn't seasoned for 2+ years, it is not dry enough to do what you are asking.

pen
 
Englishteacher said:
Let me see If I'm getting it.

With a newer secondary-burn stove "burn cycles" are an important key to stove efficiency.

Yes most definately

The least efficient method of burning being: burn as much wood that will fit wide open, get quick but short-lasting interior heat wasting both wood and heat.

I would say so... Wide open will burn extremely hot, thermo nuclear hot, but.... you are sending all that heat up and out, which is not the goal.

The air intake is not a hot/cold dial on a refrigoator but a tool to be used to facilitate the most efficent burn cycle and that(counterintuitively to me at least) turning down the air intake at the right times in the cycle actually creates a hotter stove and fire not a cooler one.

Yes with properly seasoned wood. Closing the air down will indeed create a hotter stove. You will be burning all the fuel including the gasses that are flamable. That is what these modern stoves are designed to do.

Assuming a consistant quality of wood, and that one attends the air intake properly, in an efficent burn cycle what actually effects the heat is not how open or closed the intake is but merely how much fuel was/is in the stove.

You MUST have a high quality (read, well, or at least properly seasoned) fuel. Then yes the amount, and type, of fuel will effect the burn time as well as the heat. A fully loaded stove of say Pine will burn extremely hot and extremely fast as compared to a full stove of Oak which will burn freakin hot but also for much longer. The Oak will also coal, in general, better than the Pine, which makes the reload a much more pleasurable experience.

Am I getting this?


Seems to me you are getting it. There is more than just these factors but... now you see broken grasshopper the way of the wood(burning)chuck.
 
I would order a moisture meter from Harbor Freight (or buy one from Lowe's) and test that wood of yours. Any oak that comes from a wood dealer is more than likely pretty green. I wouldnt doubt if its in the high 30's%..... and thats not good.
 
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