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Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Caruso293, Jan 16, 2013.
Ah, I can't keep up. 1, 4, soon to be more.
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Don't open and close the door so much
Are we taking "face cord" or "true cord" that seems like an awful lot of wood??
Back to the uninsulated liner post, I heard the main reason for one to insulate his liner is to slow creosote formation in the liner by keeping it warm. How can insulating your liner change the way your stove burns? How could it burn longer?
I'll take a shot by saying it creates a better draft from being warmer so it allows the stove to be dialed down more, makes for better secondaries and the fire won't smolder when dialed down. Obviously some chimney's will draft great no matter what due to height but I could see a 15' chimney benefiting from insulation.
I'm on 8 hr cycles and that's with temps about 30 degrees warmer. But we do have some fir mixed in.
Knew it the moment I saw the avitar. Before I noticed the nym.
OK im just askin this cause Im curious and don't think in my mind like your saying. I may be wrong though?? I DO agree a warmer chimney should create better draft. BUT when turning the air down lower do you REALLY increase your burn time? Your dialing air down for a given draft to create a long burn, but if your draft is not as strong you leave the air open a bit more,BUT its not sucking in any more air into the stove at a similar burn rate because the draft is slower so its not sucking in as much air as the stove with a strong draft at that same setting??
Confused you yet or did I explain my thought on this enough for you to understand where im coming from?
No clue, just took a shot. I had never heard it burning less wood before reading Ed's post so I just went with it. My thinking was on a non cat the better the secondaries with less active flames on the wood the longer the load would last since you get better secondaries with a better draft. Of course it's a fine line between the perfect draft, too much or not enough. I was thinking a 15' chimney with insulation or not, my 30' would draft fine with or without. My experience with a non cat and a good draft was not good so I now have a cat stove.
I figured someone smart would answer by now, I was hoping to drum up the answer for Ed.
Well I have a CAT stove at the house. I do have a tube stove at the farm, on a 13ft chimney that's uninsulated and I have yet to burn optimum wood in it yet, needless to say I have not been thrilled with it?
I been married a long time......my advise, put more wood on hog
Hard question to answer. Individual setups are all different. My new Hampton has just over the 12 ft minimum chimney at my elevation. It drafts great. In fact, I put a pipe damper in the double wall stove pipe for emergencies and now find on cold windy nights with a full load, I can get the load settled in with secondaries and close the pipe damper all the way. Go figure...my chimney is 13 feet total.
67 with a wood stove sounds cold. Even one the lowest setting my place is 77 with 30 Deg outside,and i only got 1 stove at home and its in the the basement.
I do two full loads and a half a load. When I get up at 630 I load the stove full. When i get home at around 730 i throw in a few small peaces to get the coals going. That brings her to 500-600, by 10:30 or so I fill it up again, then do it again tomorrow. Each full load i average 8 large splits and a few small ones. On average I go through 16 to 20 pieces a day. I have thousands of like size splits in the back so do the math. lol.
I'll give it a try.
Let's say my chimney is 20 feet tall and my chimney/liner is not insulated. Cold air is denser and heavier than warm, so I will have a good volume of cold exterior air in my chase/chimney. This will keep my uninsulated liner quite a bit cooler than it would be if lined. This cold air is heavy, and will want to stay down in the chimney. If I am burning, the liner will get warm, and that will warm some of the air in the chimney/chase as well. so some of that air will rise and be displaced by cold exterior air. So, I'll have two drafts going, one in the liner, and one in the chase/chimney. The greater the differential between the temp in the chase/chimney and the flue/liner, the greater the draft in the area around (outside) the liner/flue will be. The greater that draft is, the more rapidly the cold air outside will replace the slightly warmed air in the chimney. And the more rapidly it is replaced, the less time it has to warm, and the more cold air you are pulling down into your structure. And the more cold air there is available to cool the insert/flue.
If the flue/insert is insulated, there is much less heat exchange between the flue/insert and the air outside it, within the chimney. So that air does not heat as quickly, and will be sluggish and sit around the liner/flue more. It will very gradually heat, and to a lower temperature. That heated air will rise, but more slowly, and it will be denser because cooler, so there will be less differential between it and the outside air, so the draft will be much lower (I'm talking the draft AROUND the flue/liner. So your flue/liner loses less heat to the outdoors and stays warmer, and the area around the flue/liner stays warmer, so your home should also be a bit warmer.
Now, let suppose that with this 20 foot chimney and an uninsulated flue/liner, I am able to shut the air down to just open a fraction, and I get a good secondary or cat burn. I have a certain size opening letting air into the stove.The air is being pulled into the stove by the draft created by the air exiting up the chimney at a given speed. The cold air around my flue/liner is cooling the inside air in the flue/liner somewhat, and doing so more the colder it is out, because not only is the outside air colder to begin with, but also the differential between the inside and outside is greater, creating a greater draft around the flue and moving more cold particles by it each moment, and each particle passing along it is exchanging heat with it and cooling it a bit. So the possible draft inside my liner is kept somewhat lower by the cooling of the exhaust gases as they rise. The cooler they are, the less excited the particles in the air are, and the slower the air moves. The slower it moves up, the slower air is pulled into the stove. The slower air moves into my firebox, the less the volume of air that enters it in a given time., The less air that enters and leaves, the less oxygen in the stove in a given time,. The less oxygen in the stove the less fuel for burning the wood. The less fuel for burning the wood, the more unburned gases escape up the flue. The less oxygen inthe firebox, the cooler the burn will be, and the more primary as opposed to secondary burning will take place. More potential heat will be lost up your chimney, less heat over the length of the burn will warm your home. The slower the air moves up your insert, the more time it is in contact with the cooling exterior chimney air, and the more it cools and slows down, and the more likely your are to have creosote formation.
Now, if you line that flue/insert, and shut the air down on your 20 foot liner to the same setting, you are able to keep most of the warmth in the flue from meeting the colder chimney air. This keeps the chimney air from heating so fast, so it stays stiller longer, is displaced less frequently, moves along the flue taking heat away from the flue more slowly, keeps that area warmer and thus the home somewhat warmer than with an uninsulated liner. It also greatly reduces the amount the outside air is able to cool your flue, so it lets you maintain a higher stack temperature, which means that at the same setting (air opening), you will have hotter air leaving the flue. The hotter air is more excited and moves faster. It pulls more air into the firebox much more quickly though the same size opening. The air moving much more quickly though the same size opening brings with its increased volume more oxygen. There is now plenty of oxygen as fuel to let all the gases burn. The gases burn really hot, and the depleted air and burn byproducts are hot and move rapidly out of the firebox and up the flue, as new air/oxygen is introduced.
Now you are able to close the air down further, maybe half way or the remaining possible amount, or maybe all of it, depending on your set up. Hypothetically, lets say you close it enough so that the opening is small enough to let the same volume of air into the firebox that you let in at the larger opening/slower draft. So now you don't have a richer amount of fuel, you have the same amount. But you do have it moving through the firebox faster, so it burns the volatile gases that are high in the firebox really well, but it doesn't sit very long on the logs, so it doesn't have time to burn them as much. So, while you get a really efficient burn, you also get a longer burn.
That's what I think happens, more or less.
rideau,rdust thank you both fot the responses, I'll PM you guys so I dont take over the thread.
That is if your near the stove!! But my bedroom on warm nights is just 70F and will normally be in the 67 range. Cold nights its close to 61 in the mourning. But i am as far away from the stove as you could get and there is no wall insulation in my house. I could not sleep with it 75 in my bedroom, unless i just use a sheet and small blanket maybe? But the point is that everyones house is different as well as thier sleeping conditions.
It all depends on the house size and outside temp.
No stove is going to heat this place at 2600sf (not including the basement)from the basement.
When it is single digits out with 0 or below wind chill, what we wake up to, is what we have. 65 this morning when I got up.
At 30 degrees outside, yeah sure I can have this place around 77 downstairs, upstairs even warmer, but that is too damn hot for me.
The insert is doing just fine.
My bedroom stays about 70 and its 2 floors up from the stove. I do need 2 fans to circulate the air or my stove floor would be 90 and the next 2 floors up much colder.
Your insert is in the basement?
For some reason i can get the house a lot hotter with the wood stove rated at 75000 BTUS than the coal stoker boiler rated at 90000 BTs. So it seems either the wood stove is under rated or vice versa.
Maybe your coal isn't as well seasoned as it should be ha!
It is crap, this year ,a lot of ash for not so much heat. THere is one place that always has good stuff,but it gets so hot it cracks the grate every year without fail. My wood is 3 year seasoned oak ,premium stuff.
Believe it or not...yes lol He's my fiance