Burn times

[wg_bent]

One of the big questions in peoples minds when they're purchasing a wood stove is the REAL burn times.

O.k. so here's the mine...Osburn 1800 - about 6 hours on a full load on low... 3 hours on a full load on high.

 

[Sundeep Arole]

These numbers would be worth tabulating. Something like model, insert/stove, firebox size, area of immediate heated space, type of connection to chimney, chimney height, and burn times with a full load on high and on low. Anybody think we should have more info? I've started a spreadsheet. Similar data could be collected for pellet stoves - any idea what parameters might be useful there?

 

[Roospike]

PACIFIFC ENERGY Summit Classic~Porcelain Enamel in “Sunset Red” Free standing stove “our burn times” have been 8-12 hours with coal up to 14 hours on coal heat@ lows of 30 deg.. When it gets 50-60 deg we run 1 log every about every 8 hours to keep the chill out . Heats the whole house and does it very well. 6-8 hours burn time with really good heat @ 20 deg and lower out side and that keeps it 72-75 downstairs and 70-72 up stairs~ * Copied from my other post in pictures *Our house is 100+ years old with storm windows and blown ins in the walls and attic , the house has been redone so it not the same 100 year old house. The logs we burn are normaly the better btu woods abd the most wood i have used at one time is 3 split logs but normaly its just 2 at a time . Like i said the coldest we have had so far is 18 deg at night . The logs are what you would think of logs for about 6 hours and then after that they look like coal logs for the other 4-6 hours. I was very pleased when we ended up getting over 8 hour burns with good heat because i thought “ 8 hour burn time , yeah right” so Pacific Energy says but thats what we have been getting on this stove. We use our full round logs for night burns with a split log ( 1 round 1 split ) and just split logs is the day. I would say our average round logs are 9” across and 16” long and ther will be nothing but ash "after 14 hours" if we let it go without a refire. The top steel plate of the stove is 3/8” thick tho our top is under the out side porcelain plate that 3/8” thick top keep the heat rolling. “Correct me in I’m wrong, but does your model have the auto-thermostat feature?” Yes in the EBT there is a spring that opens the fresh air inlet if you run the damper in the stove too low. You cant go wrong on too low of draft that you set just as long as you get the wood burning at first for 15-30 min before you close down the damper on the stove the auto spring in the burn chamber takes over if more air is needed. We had a high demand from this stove for the $$ we paid and when we started burning wood in it the stove is 4 time better than what we expected. “ Nice porcelain finish - holding up well with stove use? “ we have only had the stove for a short time but so far it keeps its shine and cleans up very well. The “Sunset Red” color does get a bit deeper in color the hotter the stove is and than back to normal when not in use. not much change ...... just a little. picture post thread ---> https://www.hearth.com/talk/threads/93/

 

[saichele]

VC Large WinterWarm - about 6 hrs on full load with low setting. Relightable coals to about 8 hrs. Burning red oak, ash, and beech.

Steve

 

[babalu87]

Got a solid 6 hours last night.

Still trying to learn how this stove burns (just installed it before Thanksgiving) but I packed it pretty good last night at 11pm and at 5 am I had enough coals to get it going again easily.

I could have put a few more logs in so I am eagerly anticipating a 7+ hour burn time

 

[wg_bent]

These numbers would be worth tabulating. Something like model, insert/stove, firebox size, area of immediate heated space, type of connection to chimney, chimney height, and burn times with a full load on high and on low. Anybody think we should have more info? I've started a spreadsheet. Similar data could be collected for pellet stoves - any idea what parameters might be useful there?

Great, after I posted that I had a similar thought.

So.

Osburn 1800i, 1.8cuft, 1500 sqft heated space, Full liner in 0 clearance chimney, 20' tall chimney

Also add -

Type of wood burned - Mixed hardwood
Age of stove - 0
Type of alternate heat source - Oil/hydronic baseboard
State or location - NY

Hmm, Big variation in burn times on those Pacific Summits. One is an insert, the other a freestanding, yet burn times see real different. I'm feeling more of that government study comming on. Elk - get the beer, Eric - get the stack thermometer

 

[Rhone]

Warren, if I remember correctly Roospike throws in actual "logs", as in 9" round unsplit logs like an outdoor furnace. Frank Ivy burns log splits, why the discrepancy in times.

Hearthstone Clydesdale Soapstone Insert

Wood: Red Oak, Black Cherry, Ash

Max air setting: fire for 4-5 hours, coals can be found if I dig for up to 8, fans stay on for 6-8 hours
Medium: fire for 6-9 hours, fans stay on for 8-10 hours and keeps my house around 70
Min air setting: I used it once, I don't like how it burns and I can do an overnight burn at medium setting. Fire burned for 9 1/2 hours fans stayed on for 11 but you really need dry wood for any "heat" and it needs to be a rather warm night (mid 40's+) or a very efficient house else lose ground.

 

[Rick]

I have a Hearthstone Bennington.
Double wall for ~ 6', then ~ 18 feet of Secure-Temp ASHT+ chimney.
Mixed hardwood.
After establishing a nice bed of coals (roughly 3 inches thick) i get about 5 hours on a full load. At that point i can still just add more wood without any fuss. After about 6 hours I have to rake the coals and add some smaller splits, etc. At about 7 hours all I have are hot coals. After 8 - 10 hours I have coals mixed in with ash, but enough to re-light the fire. There are coals for at least 12 - 14 hours, but they alone can not restart the fire. I run move stove pretty much wide open, damping down only at night after the wood has turned mostly to coal. I use a lot of wood, but my wood is free. I'm only trying to heat the room that the stove is in, it's 1000 sf on slab, 10' ceilings and uninsulated walls. I can keep that room to about 72 but i lose 5 degrees an hour after I go to bed, so by morning it is 54 degrees, the temp the furnace is set to.

 

[Willhound]

Alright, I've resisted this, but no more . . .


Edit
I just don't buy that you can get 10-12 hour burns in a 3.0 cf firebox. I'd have to see that to believe it. Particularly when the person posting this is saying that they have never put more than 3 splits or 2 splits and a round in the unit at one time.

You put in two splits and you get 8 hours of good heat? That sounds like the world's energy problems are solved.

18 degrees at night, the whole house is 72-75 degrees, burning 2 or 3 splits at a time, max, getting 8 to 10 hours out of each split?

So you burn 6 to 9 pieces of wood a day? And the house is above 72?

Anybody else burning 9 pieces of wood a day and it's below freezing outside and your house is 75?

Please. I don't think anybody who has ever burned wood for heat would believe that.

Edit

And by the way, your understanding of the EBT is exactly backwards.

It doesn't open up to let in more air if you damp down too much.

On the contrary. What it does is damp down the air if the heat in the unit gets too low so that the remaining wood isn't fed too much air.

The alleged purpose of the EBT is to extend the fire burn time. You cannot extend the fire burn time by introducing more air. On the contrary - you extend burn time by reducing the air.

Frank

With all due respect, I think that you may have the EBT thing backwards. In fact it does open at lower temps to let more air in and bring the fire back up to temp if it is damped too low or has burned down too far for the air setting you have it at. Our friend the Chimney Sweep has the explanation and a good diagram at (broken link removed to http://www.chimneysweeponline.com/hoebt.htm) (Willhound's edit - I shouldn't say it "opens at lower temps", it is actually always open at lower temps and closes as temps increase)

This also makes sense in that the EBT will initially be open when you first fire up and provide additional combustion air to get you going. After temp is reached, EBT closes to run the unit off just your front damper, and then re-opens as temps fall to re-ignite as per the explanation. After optimal temps are reached it closes again and the cycle goes on. This is why the Summit has such a great EPA rating as it maintains as much as possible an optimal burn temp, and also makes good use of all available fuel. And, if the thing does ever fail, i.e the spring lets go, it will fail in the open mode, therefore allowing you to still adjust your fire with the front damper until parts come in. That being said, my dealer and installer tells me that he has never seen one fail in the 15 years he's been handling the Summit.

Also, a very good friend has a Summit freestanding and reports similar wood usage and burn characteristics as Roospike. We get very cold here in winter and my buddy reports that he averages around a dozen split and round pieces of dry birch used most days. Sometimes a few less, sometimes a few more, but always between 8 - 15 max. In fact, it was this information that finalized my decision to goi with the Summit insert as it has identical internal construction as the freestanding. He also reports burn times of a good 8 - 10 hours and hot coals up to 12, where he just rakes them around and throws in a few new pieces and gets re-ignition.

His installation is also very similar to what Roospike has described, so perhaps the differences are not in the units, but in the individual install circumstances.

Now I have to qualify this by saying that this is the info as supplied to me by my buddy. I'm still waiting for my insert install (supposed to be tomorrow), so once up and running I can join in with my own personal experience.

Willhound

 

[Roospike]

Alright, I've resisted this, but no more . . .

Not to always play the cynic, but I gotta say, wood burns the same anywhere in the world given the same oxygen content of air, right?

So the only thing that is really going to affect your burn time is the amount of wood you have, the type of wood you have, and the amount of draft you have. Right?

For any stove that is 3.0 cubic feet, which most of the big ones are, you are going to have only so much fuel in the firebox. If you burn the fire hot enough to keep it going, you are going to be burning the wood at a certain rate.

I just don't buy that you can get 10-12 hour burns in a 3.0 cf firebox. I'd have to see that to believe it. Particularly when the person posting this is saying that they have never put more than 3 splits or 2 splits and a round in the unit at one time.

You put in two splits and you get 8 hours of good heat? That sounds like the world's energy problems are solved.

18 degrees at night, the whole house is 72-75 degrees, burning 2 or 3 splits at a time, max, getting 8 to 10 hours out of each split?

So you burn 6 to 9 pieces of wood a day? And the house is above 72?

Anybody else burning 9 pieces of wood a day and it's below freezing outside and your house is 75?

Please. I don't think anybody who has ever burned wood for heat would believe that.

What have you got? A flux capacitor in the thing?

And by the way, your understanding of the EBT is exactly backwards.

It doesn't open up to let in more air if you damp down too much.

On the contrary. What it does is damp down the air if the heat in the unit gets too low so that the remaining wood isn't fed too much air.

The alleged purpose of the EBT is to extend the fire burn time. You cannot extend the fire burn time by introducing more air. On the contrary - you extend burn time by reducing the air.

First ... I would like to say , This is going to be my only reply to this statment . I've seen the other threads going on for days pissing back and forth with Frank . Nothing aginst you Frank , I'm just not going to do it. The wood i burn depends on the weather . 50-60 deg I burn mixed woods and splits at that . Over night burns i burn rounds . When i gets colder in the days i burn Red oak - white oak and mix of my other hard woods Ash , locus ect . When colder at night 30's & below i burn "rounds" of red oak , white oak & locus . I do have some softer woods to mix it up a bit and to restart fires in the spring and fall and to get quick heat if needed. I have been burning wood for over 12 years so just because my stove is new does not mean i am new at it. Every house if different as is yours Frank. So when i get 8+ hours of burn time , its logs at first then it goes to coal logs than to coal is we all do. I dont know about your house but this is all the heat i need for 8+ hours . I dont need to keep my stove burning at max all the time to keep my heat. If you cant keep the heat in your house with the wood that has burned for 6+ house and the coal logs after that is still glowing for 4+ hours then you have a house issue not a stove heating and wood burning debate. Last time , Frank , you had to go aginst my wood butning times you said

Our current house is about 2600sf, with 200+ sf in a basement finished space that I refuse to heat in the winter.

I don't have any rounds for this winter, as I bought wood -

Then you mentioned about "it could be the wood" and said something about might be burning softer wood and pine. So Frank , Your wood being bought and unsure of what is it changes things ia little bit. As for the Pacific Energy Summits EBT ( extended burn technology ) This is what "Pacific Energy" told me. The EBT is run throught the bottom of the stove through a different inlet. When the damper is closed down all the way the spring in the EBT unit controls the secondary air to "UP" the air supply through the secondary burn chamber and or "lower" the air supply as needed. When the front air damper is down all the way the EBT controls the air flow. So if this stove didnt have the EBT on it (for example) and you turned down the damper all the way your fire would end up going out or you would have it set too low and have build up iny our pipe. The EBT controls the low burn air supply( UP and DOWN ). It dont just "cut down" the air supply as Frank has stated. Another thing about the PE summit .... If soembody , for some reasion went and put a PE Summit in there "BARN" and said they had to run it on on high all the time and was only getting 4 hour burn times and also didnt know what kind of wood that they had bought , burning only splits .........This means nothing to me and my "HOUSE" with "MY" burn times nor does your burn times and what ever wood you might have Frank. Apples VS apples Frank , you keep throwing Oranges at me.

 

[Roospike]

I'm only trying to heat the room that the stove is in, it's 1000 sf on slab, 10' ceilings and uninsulated walls. I can keep that room to about 72 but i lose 5 degrees an hour after I go to bed, so by morning it is 54 degrees, the temp the furnace is set to.

Wow , where do you live ? I am no builder so i cant understand why a house would be built with uninsulated walls . I was at a house in Florida (1800 sw ft 2 years old $200K ++ ) and they had a central air system in it AND wall A/C's in each bedroom ! I thought this was very strange ,,,, I asked about it thinking the central A/C didnt cover the bedrooms ........But they did . He said there was uninsulated walls in the house and the central A/C cant keep up. Now why in the world would a house be built like that???

 

[Rhone]

I don't want to get into the debate, I thought EBT worked like chimneysweeponline said until I saw the patent itself. Go here and read the "Summary of the invention" EBT Patent which says it works opposite to a bimetallic air control in that it stays closed until the secondary burn can be engaged. At which, it opens engaging the secondary burn. Once the fire has settled & cooled down, the EBT device closes and the secondary burn disengages.

What it appears to do from the patent is prevent flooding the insert with air before it's hot enough to engage the secondary burn, and likewise when the fire is dying and no longer hot enough for secondary burn, prevents flooding it with air then also. Flooding your unit with air before the secondary burn is ready wastes heat out your chimney and slows down when your unit is ready for secondary burn. Likewise, at the end when it's no longer hot enough, it prevents blowing heat out your chimney. It also is either open, or closed. There's no "in-between" state. That's how I interpret the patent, and you can click on the "image" on that page to see the actual EBT itself. I'm no expert on understanding or reading patents.

 

[Rick]

Wow , where do you live?

I live in Connecticut. This room used to be a separate building that housed a wood shop for the homes builder. The people I bought it from attached it to the house with an uninsulated walk way and converted the wood shop into a family room. I didn't realize the walls were uninsulated until this year (my third in the house).

Rick

 

[Roospike]

I don't want to get into the debate, I thought EBT worked like chimneysweeponline said until I saw the patent itself. Go here and read the "Summary of the invention" EBT Patent which says it works opposite to a bimetallic air control in that it stays closed until the secondary burn can be engaged. At which, it opens engaging the secondary burn. Once the fire has settled & cooled down, the EBT device closes and the secondary burn disengages.

What it appears to do from the patent is prevent flooding the insert with air before it's hot enough to engage the secondary burn, and likewise when the fire is dying and no longer hot enough for secondary burn, prevents flooding it with air then also. Flooding your unit with air before the secondary burn is ready wastes heat out your chimney and slows down when your unit is ready for secondary burn. Likewise, at the end when it's no longer hot enough, it prevents blowing heat out your chimney. It also is either open, or closed. There's no "in-between" state. That's how I interpret the patent, and you can click on the diagram.

I think your "right on" The EBT inlet is "under" the stove ( free standing anyway ) at the bottom. Different inlet from the front air supply.

 

[Rhone]

Well, I renege on the idea it controls secondary burn because I just scoped the patent again and there's no mention of secondary burn. What it does say, is that when temperature rises it opens a flap to allow extra air into the combustion chamber (not secondary air supply) and something to the effect of lowest air setting with large units and EPA. Anyway, people can read and interpret the patent as they see fit but it doesn't appear to work like chimneysweeponline seems to suggest.

 

[Willhound]

I dunno. I will admit that in my post above I was slightly off when I said that if the EBT fails it will fail in the open mode therefore allowing you to control the burn with the main damper. In fact, it appears that when the EBT opens up it bypasses the draft control and allows a full shot of air into the burn chamber regardless of where you have your front damper set.

OK, but, my understanding is still that when the fire dies down too low and is operating below a temperature that supports secondary burn, the EBT opens up and allows more air in to increase the burn rate and get temps back up and secondary burn going again. Yes, it burns more wood for this period.

But..once temps are back to optimum and secondary burn re-established, EBT closes, thereby "evening out" the burn rate of the wood, therefore this is where the wood savings comes back into play, unlike a standard stove where you are constantly fiddling with the draft control to get a good burn, but not keeping as good a control on it as the automatic EBT does ? You know, the scenario where you come into the room and see that the fire has died down too far, so you crank all the dampers open to get it going again, and then 30 minutes later, remember to go and shut it down again.

I think a good comparison is like gas mileage in a car. If you are constantly either on the gas, or on the brakes to control speed you will burn more gas (conventional stove) versus slowly bringing the car up to speed and coasting when you need to control speed (EBT).

Willhound

 

[Roospike]

Wow , where do you live?

I live in Connecticut. This room used to be a separate building that housed a wood shop for the homes builder. The people I bought it from attached it to the house with an uninsulated walk way and converted the wood shop into a family room. I didn't realize the walls were uninsulated until this year (my third in the house).

Rick

My house is 100 + years old , no uninsulated walls when built , back 40+ years ago the walls look to be insulated but has turned to dust at best and was setting at the bottom 1/4 of the walls. We bought the house, remodeled it and took out the plaster and kept the lath boards in , took out what was left of the insulated walls , put up dry wall ( sheet rock ) and had the blown insulate put in from the out side once the house was finished. ( blown in through the out side walls per drilled holes ) The plaster being taken out was a he11 of a job and we just left the oak laths on the oak studs. Maybe you could blow in your insulate. Our cost for all the walls and add 12"+ to the attic was $475. ( two story 1800 sq ft house )

 

[Roospike]

The EBT unit is on the primary air control (see Figure 1 of the patent where this is clearly shown).
Figure 2 of the patent shows the EBT when the unit is cold. The flap is closed, so no air (or reduced air) is going to the primary air supply.
Figure 3 shows the EBT when the unit gets hot and makes the bimetallic coil extend. The flap is open.

OK , To make it basic , your telling us that when you have the damper open getting the wood burning and cranking on the heat that the EBT is "OPEN" = stove is hot . Alsoy your telling us that when you turn the damper down to low ( stove cools ) the EBT then is closed. Sooooo there would be no point to a EBT unit than Frank . Anyway. for everybody elses info , When running the stove this is what i see in the fire box . When burning wood at where ever on the damper except LOW the air is comming in from the front air inlet under the front door and also the top air wash system that is hooked to the front , at the front and NO air that can be seen comming from the top of the secondary burn chamber that is hooked to the back of the stove. Now , When the front damper is CLOSED or all the way on low i see no air pushing from the front of the air inlet ( low air comming in ). all the air is now comming from the top of the secondary burn chamber that is hooked to the back of the stoves air supply . Soooo , that means to me that there must be a second air supply comming in when the front damper is set to low . Whre is this second air supply comming from ? Hummmm , Aw .. Maybe the EBT has kicked OPEN to burn the smoke that is now comming from the wood because the main air damper is now set on low. There are two different air supplies, The main damper from the front and the EBT damper from underside of the stove. I can see this because i have a freestanding wood stove , this would be a little hard to see when you own an insert. What you say Frank just does not make any sence.

 

[Rhone]

The EBT is automatic regardless of where you set the damper. What I gathered from Franks post is that lets say you set the damper, doesn't matter max or min. Well, it doesn't allow "full air" into your unit until your fire is hot. Once it's hot THEN the EBT opens up automatically letting in an air boost and NOW you're at more air while the fire is going good. As your fire dies down, the EBT closes automatically letting in less air to your fire to extend its burn.

If you look at (broken link removed) it's the part numbered 14. It looks like the boost air comes in from the bottom front, I see no channels going to the top or rear off the EBT. Anyway, that's how I see it now and I may not be correct. But, that goes along with what you're saying. You say the air comes in from the bottom front except on minimum burn. That looks like where the EBT lets in its boost air. There's also air coming out the air wash & secondary burn regardless of the EBT status. On lowest burn you mention the air doesn't come from the front, maybe because it stays too cool for the EBT to open so all your air comes in from the top out your airwash & secondary burn. What's interesting is, I bet that keeps your glass cleaner as low burns are notorious for dirtying up glass. Actually, it's low burns and starting a fire before it really kicks in. The EBT appears to direct all the air so it comes out only through the air wash & secondary burn in those two cases and probably contributes significantly to cleaner glass. After looking at the patent and understanding how it works I think cleaner glass is its purpose! What's interesting is that when it does open and boost air during the "hottest phases" of a fire, that's the phase that cleans the glass. Boosting air during those times is more likely to burn off any debris that's collected on it. Hmm... sounds like there's an ulterior motive of the EBT. It directs most of the air down the airwash during the beginning of a fire and on minimum burns, the dirtiest parts of a fire so keeps it cleaner. Then, it boosts the air during the hottest phase of a fire the part that burns off debris on your glass to keep it clean. I'm going on a whim here, but I think its purpose is to keep and maintain clean glass. Ingenious, the patent doesn't appear to say anything of that nature but after hearing you describe it in action and how the patent is I can't see how that wouldn't be its main purpose, the fact they say the main purpose is extending your fire and helps EPA levels to me is secondary to how it keeps your glass clear. Hmm....

 

[quads]

Make/model: ? Fondly referred to as "Old Smokey". No EBT, ESP, or any other funky mechanisms.
Firebox size: A little smaller than a VW Bug?
Heated space: Whole house is 900 sq.ft.
Chimney height: About 4 sections of cleaning rod.
Type of wood burned: Mostly black oak, some white, usually seasoned, depends on when I cut it.
Age of stove: 30+ years.
Length of burn: Easily throws heat for 8 hours at below 0*F outside temps (which it has been lately), or twice that if I make her smolder and very little heat output.
Type of alternate heat source: Summer.
State or location: The northern tier.

 

[adrpga498]

OK first, apologies to Roo.

I suffer from behaving like a child on an intermittent basis.

My last post was one example.

That written, I still have to respectfully wonder if you aren't exagerating a bit. Willhound's added data has made me wonder whether I'm wrong, however. I note this particularly in light of Roo's setup, which to me is the ideal setup with a perfectly chosen stove.

But I note the following - at 10 pieces a day, which is more than you say you're using, you need about 1,500 pieces to burn through 5 months of winter. So I went and checked my wood pile, and 15 pieces gets you about to 5'. So you need a row 100 pieces long and 15 pieces high. Which is about 33 feet long by 5 feet high. Figure 16" lengths, as you noted, and you get 33x5x1.33=219 cubic feet. Which is 1.7 cords of wood.

Seems to me that there are two ways to heat a house with 1.7 cords of wood.

1. Have a 1,000 sf house.
2. Have a super duper insulated house like BeGreen's friend with double 2x4 (8") well insulated walls.

Better yet, however, I could do a quick BTU calculation. Just randomly weight 10 splits. Then do a BTU calculation for Oak, then extrapolate over 24 hours. I won't do it, but I'd wager that the result would be 30-40k BTU equivalent, which ain't going to heat a standard house.

RooSpike, you did your setup right, and I apologize for accusing you of hyperbole.

NOW FINALLY, with regard to the patent, I'm going to make my final post here on Hearth.com about that patent - because it's near and dear to my heart. I can promise you that I know more about that patent than anybody at Pacific Energy who picks up the phone or any Pacific Energy dealer, with the possible exception of Paul Erickson, and I'd still know more than him about what the patent claim coverage is although he'd know more than me about the science.

I have just read it for about the 4th time.

I don't claim to be an expert on much, but I'll note this.

I am an expert on patents.

If you want to know what the patent is for, read Claim 1.

It clearly describes how the flap functions. The flap is closed when the unit is cold. It opens when the unit warms. It closes back down when the unit gets cold again. Very simple. It's purpose is single - it reduces the primary air supply at the front of the unit when the fire starts to burn down to prolong the fire.

Guys, think about it. It's extended burn technology. Not clean burn. Not better burn. Simply, extended. The only way to extend a burn is to make sure that you reduce O2 to the fire so that is burns more slowly.

The EBT unit is on the primary air control (see Figure 1 of the patent where this is clearly shown).
Figure 2 of the patent shows the EBT when the unit is cold. The flap is closed, so no air (or reduced air) is going to the primary air supply.
Figure 3 shows the EBT when the unit gets hot and makes the bimetallic coil extend. The flap is open.

The background section of the patent offers . . .

"Traditionally all bi-metals are configured to close air inlets when the temperature rises. Thus, as the temperature rises, the fuel consumption increases, the bi-metal senses the temperature rise and begins to close the air inlet."

The summary of the invention adds. . .
"The control system [of this invention] works opposite to the traditional bi-metal control systems because when the temperature rises the bi-metal opens the flap against gravity, thus additional air intially increases stove temperature which causese the bi-metal control to continue opening the flap."

So this is really pretty simple. The unit gets hot, the spring springs, and more air is fed in. The unit cools down, the spring unsprings, and less air is fed in, extending the burn.

That's it. The Chimney Sweep description is wrong. Whatever anybody else heard is wrong. Whatever the person at PE said on the phone is wrong. Whatever the dealer said is wrong.

I would comfortably stake my professional reputation on my interpration of U.S. Patent 6,041,770 to Erickson.

The patent is extremely clear about what the unit does.


Will hound, you're going to love this insert. I wish you the best with it.


For the rest of yooz guys, take care - I've got 6 weeks worth of work I need to catch up on before I drown.

Read the book I sent Steve - it tells a tale.

Frank,

There's a third way to heat your home with 1.7 cords of wood, and I'm surprized that it escaped you: Establish 50-55 degrees as your comfort level.

Dylan

LOL
Dylan , your the best. Short & to the point.

 

[Willhound]

OK first, apologies to Roo.

EDIT

If you want to know what the patent is for, read Claim 1.

It clearly describes how the flap functions. The flap is closed when the unit is cold. It opens when the unit warms. It closes back down when the unit gets cold again. Very simple. It's purpose is single - it reduces the primary air supply at the front of the unit when the fire starts to burn down to prolong the fire.

Guys, think about it. It's extended burn technology. Not clean burn. Not better burn. Simply, extended. The only way to extend a burn is to make sure that you reduce O2 to the fire so that is burns more slowly.


So this is really pretty simple. The unit gets hot, the spring springs, and more air is fed in. The unit cools down, the spring unsprings, and less air is fed in, extending the burn.

That's it. The Chimney Sweep description is wrong. Whatever anybody else heard is wrong. Whatever the person at PE said on the phone is wrong. Whatever the dealer said is wrong.

EDIT

I guess Frank that we'll just have to agree to disagree on this one. I know that you said in your last post that this was as far as you would go with this, but to make one last point, I have to agree with Roospike on this one. If the purpose of the EBT was to continue to cut off air as the stove cools, then it really serves no purpose. You could do the same thing by leaving the damper on the lowest setting. Yes, I too read the patent, and while I do not profess to be a patent expert, I think that there is a point that you are missing if you read the patent carefully. Because of the dual lever design of the flap, at no time does the EBT "reduce" the amount of air. When EBT is not activated the stove is relying on air from the damper handle on the front of the stove, right? The owner can crank it wide open to make things take off, or damp it right down to slow down the burn. When EBT kicks in, it closes off the air supply from the owner controlled damper and allows a fully open supply of fresh air from under the unit. More air than you had with just the damper set. Why? Because you need to EXTEND the burn, as you point out. By allowing in more air, it allows the fire to continue to combust at a decent rate. Otherwise, you might as well just damp it down all the way and conserve your wood, because it will just smolder all night long and most of the wood will still be there in the morning. Yes, it extends the burn...by keeping it burning.

Willhound

 

[BrotherBart]

Make/model: ? Fondly referred to as "Old Smokey". No EBT, ESP, or any other funky mechanisms.
Firebox size: A little smaller than a VW Bug?
Heated space: Whole house is 900 sq.ft.
Chimney height: About 4 sections of cleaning rod.
Type of wood burned: Mostly black oak, some white, usually seasoned, depends on when I cut it.
Age of stove: 30+ years.
Length of burn: Easily throws heat for 8 hours at below 0*F outside temps (which it has been lately), or twice that if I make her smolder and very little heat output.
Type of alternate heat source: Summer.
State or location: The northern tier.

Thank God I'm not the only dinosaur on the Forum. I bet your stove has the same four temperatures Big Brownie has:

1. Cold
2. Hot
3. Really hot
4. Holy #$%& call the Volunteers when you get to the neighbor's house Martha!

And burn time:

Can till can't.

 

[bruce]

harman tl 200
on a full load 10/11 hr on low set with great heat and plenty to start over again, filled it today at 6:30 am, got home at 5:30 pm, and off we go again, house almost always above 70 unless below 0

 

[Roospike]

harman tl 200
on a full load 10/11 hr on low set with great heat and plenty to start over again, filled it today at 6:30 am, got home at 5:30 pm, and off we go again, house almost always above 70 unless below 0

Very nice stove . I found the site -----> (broken link removed to http://harmanstoves.com/products.asp)