Secondary Burn

[NSMaple1]

Seems to me any testing of efficiencies is rather defective if stack temperatures are not also part of the testing process.

 

[Whitespider]

So the improved extraction of energy from the wood is shown by testing while greater losses of heat up the flue is a guess that has nothing behind it.

I wouldn't say "nothing behind it."

Maybe it ain't a "test" or scientific, but flue gasses exiting the chimney are definitely warmer by feel... at least by my feel, comparing my two units. That's "something"... ain't it??

How 'bout basic reasoning?? The firebox of my elitist stove is (was) near totally lined with firebrick (refractory brick)... which insulates the steel from heat (it ain't about thermal mass as some believe). Insulating the steel means less heat for it to radiate into the space around it... and, again, it ain't scientific, but my stove heated noticeably better when I removed the bricks from the sides. That's "something"... ain't it?? I mean, the brick keeps more heat in the combustion chamber for more complete combustion, meaning combustion gasses will be hotter, meaning the gasses exiting will be hotter... the (relatively) small uninsulated roof area can only transfer so much. Admittedly, the "glass" door used on an elitist stove does allow heat radiation to escape. That's the primary design purpose of the glass IMO... fire view is just the side benefit (if it means anything to you).

I don't believe the air inlet size means a whole lot to this discussion... the DAKA inlet hole behind the draft blower ain't very big either. The solid wood is being converted into heat energy and gasses... those gasses have a much larger volume than the wood (and incoming air). Well... if you do indeed have more complete combustion, you have a greater volume of combustion gasses (which, as noted above, should be hotter), and those gasses have to go somewhere. That's "something"... ain't it??

Seems to me any testing of efficiencies is rather defective if stack temperatures are not also part of the testing process.

Agreed‼
But remember... we're talking about the Environmental Protection Agency. The whole agenda is defective... they only look at the emissions (combustion efficiency), when it would make much more sense to balance the emissions verses the energy efficiency. Think about it?? If a stove produced 10% more emissions, but was 20% more energy efficient, the total emissions would be less to heat the same area. But it ain't really about emissions or efficiency, that's just the whitewash... it's about regulation and the control/power/money that comes with it.
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[olyman]

You don't have to... it ain't about you Del_, get over it.
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[olyman]

Of course it's not about me good buddy.



.....and pulling numbers out of your arse.

and thats what fairys and gnomes do to your thought pattern???? spend less time in the garden,, honoring them,, and you MIGHT get straightened out.............

 

[Chris-PA]

Seems to me any testing of efficiencies is rather defective if stack temperatures are not also part of the testing process.

The test was not intended to test stove efficiency, it was intended to test particulate emissions. Indirectly it also measures the efficiency of the extraction of energy from the logs.

Now the discussion is about how much of that energy is lost vs. making it into the room. For which we have conjecture rather than data. The stove manufacturers don't even make up numbers for that.

The firebox of my elitist stove is (was) near totally lined with firebrick (refractory brick)

Near totally? Hardly. The bottom and a brick height on the sides. The rest of the steel and the door can radiate, and radiation is the primary means of heat energy transfer from the firebox. It goes up as the 4th power of the temperature difference.

 

[Davej_07]

I'm not one to stand on principles, they never stood on me.........but perhaps we could change the term to "more useable heat"? Obviously you can't extract additional btus from the wood, but no one can argue that you will get "more useable heat" from a stove than say, a prefab fireplace......

 

[slowp]

My elitist, communist, socialist liberal stove heats my house. I know how to run it. Having an insulated house works well. Oh, and the air is piped into the elitist, communist, socialist, liberal, feminist stove from the crawlspace of the house.

Did I mention the clean chimney after several winters of not cleaning? Of course, the gubmint is going to cause an epidemic of some nahsty and take my house away after they run me to a FEMA camp. There will be an exception for those of us who wear UNderwear....wink wink nod nod and leave the secret UN parking spaces open.

 

[Whitespider]

Near totally? Hardly.

Chris, the difference in bare steel directly exposed to the combustion chamber is huge (friggin' huge) between my elitist stove (and/or those I've looked at) compared to any of my smoke dragons... past or present. The upper part of my stove is not directly exposed to the combustion chamber... the secondary baffle sits between them (and then there's another steel heat shield between the baffle and the roof). And I did acknowledge the glass door.
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[Chris-PA]

Chris, the difference in bare steel directly exposed to the combustion chamber is huge (friggin' huge) between my elitist stove (and/or those I've looked at) compared to any of my smoke dragons... past or present. The upper part of my stove is not directly exposed to the combustion chamber... the secondary baffle sits between them (and then there's another steel heat shield between the baffle and the roof). And I did acknowledge the glass door.
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This is quite similar to the construction of my Magnolia. The brick is there to maintain the temperature of the fire to keep gasification (is that a word?!) going as long as possible. If we look at just the effect of the firebrick on heat transfer, and assume for the moment that the air inlet and gas flow up the flue are the same, and consider a situation where same energy is being released at the same rate in the fire but one has firebrick and one does not.

All that will happen is that the temperature of the exposed steel will be hotter in the one with firebrick, because that released heat energy has to flow from the higher temp/concentration in the fire to the room. If the bricks block it in one area it will have to flow through the smaller non-insulated areas, which will raise the temperature there - but since radiative heat transfer goes up as the 4th power then as soon as the exposed areas get a little hotter the transfer rate will go up very fast and the total transfer rate from the fire to the room will not be reduced.

So again, I'm not buying that there are more hot gases moving up the flue, or that more heat is moving up there either - certainly not due to the firebrick.

 

[Whitespider]

OK Chris-PA ... so don't buy it then.
But understand, I'm not saying there's zero benefit to the user from the extra heat energy extraction... but, by the nature of a wood fired appliance, I don't believe the "percentage" lost through the stack, of total heat energy extracted, changes all that much. Meaning, extracting more heat energy would increase both realized heat and lost heat, you're not gettin' 100% of the "extra" into your home... I don't see how it would, or could be possible. More heat, is more heat... wherever, and everywhere it goes. No doubt, the "heat exchanger" design of the appliance will effect the percentage... no matter what the combustion configuration.
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[Chris-PA]

Meaning, extracting more heat energy would increase both realized heat and lost heat, you're not gettin' 100% of the "extra" into your home

I agree, you cannot get all of it. If the firebox temps are higher then the amount lost up the flue will probably be higher too. But that is true as well with any stove if you open it up to get the fire hotter, and individual designs will have different heat exchange effectiveness as you say. It's just another way of saying that a stove burning hotter loses a greater quantity of energy up the stack (but not necessarily a greater percentage) - the higher temps still give much greater radiative heat transfer.

I think the issue is whether you gain more by extracting more energy from the wood than you lose by having a higher temperature (and energy transfer rate) during secondary burn. I don't see how recovering the energy in the particulates could be a net negative, and my experience is that it is not.

 

[Whitespider]

...a stove burning hotter loses a greater quantity of energy up the stack (but not necessarily a greater percentage)...
I don't see how recovering the energy in the particulates could be a net negative...

Ah-ha... so we agree than
I was never trying to claim net negative... just more heat out the stack is all.
Although, admittedly, I did leave some of that for the reader to conclude... because... well... ya' know?? Stir the pot and all.
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[Cerran]

http://www.arboristsite.com/communi...l-with-epa-phase-2.267043/page-3#post-5051173


You're talkin' "energy" efficient rather than "combustion" efficient?? Well... I don't know what the numbers are. I'm thinking your numbers are a bit low for the smoke dragon, and even more likely a bit high for the "real world" elitist stove... but let's use them. Even using your numbers it don't change my point...
7000 × 100 × .40 ÷ 12 = 23333 BTU’s per hour (average) for the smoke dragon.
7000 × 50 × .70 ÷ 12 = 204166 BTU’s per hour (average) for the modern stove

You still ain't getting more heat from half the wood... unless, of course, magic is involved.
Like I said, I might buy the same heat from 20%-25% less wood... maybe.
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I never claimed half the wood, however you are getting a lot more heat from the same amount of wood.

7000 × 100 × .40 ÷ 12 = 23333 BTU’s per hour (average) for the smoke dragon.
7000 × 50 × .70 ÷ 12 = 204166 BTU’s per hour (average) for the elitist stove.

If you load both stoves with the same amount of wood by your calculations:

7000 x 50 x 0.40 / 12 = 11,666 Btu/hr on average

versus

7000 x 50 * 0.70 / 12 = 20,416 Btu/hr on average

It has nothing to do with magic but rather how much of the products of combustion you burn off. I would make an educated guess on average across most stove models the newer stoves burn approximately 30% less wood for the same heat output.

 

[Ironworker]

The EPA stoves are designed to work better and guess what, they do. Some just dont like them for the simple reason that they feel like the government is forcing them to use a specific stove. It's simple evolution and those that can't adapt will go the way of other species that couldn't or wouldn't adapt, exstinction.

 

[Whitespider]

I would make an educated guess on average across most stove models the newer stoves burn approximately 30% wood for the same heat output.

What?? They use 70% less wood for the same heat??
Now that one I ain't buyin'... no friggin' way‼
(Or was that a typo on your part and you meant 30% less wood?? Which I still believe is a stretch.)

The EPA stoves are designed to work better and guess what, they do.

Well... I'll argue that all day long.
They are designed, out of necessity, to pass the EPA test procedures‼ Whether-or-not they actually work "better" will depend on more variables than I care to get into. For some applications they likely do work "better"... other applications, not so much.
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[Cerran]

What?? They use 70% less wood for the same heat??
Now that one I ain't buyin'... no friggin' way‼
(Or was that a typo on your part and you meant 30% less wood?? Which I still believe is a stretch.)


Well... I'll argue that all day long.
They are designed, out of necessity, to pass the EPA test procedures‼ Whether-or-not they actually work "better" will depend on more variables than I care to get into. For some applications they likely do work "better"... other applications, not so much.
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I think you missed my statement. I did say 30% less wood. You say it's a stretch, but on whole the experience over this board and the hearth boards is that the newer stoves do outperform the old ones in both heat output and wood usage.

Yes they are designed to pass EPA test procedures, but in doing so they also improve upon the old designs and improve efficiency. I have no love for the EPA, but I'm not going to discount that the new stoves work better just because they are EPA approved either.

Lets face it, you're basing your entire opinion on a sample size of one stove.

Good study on stoves to look over:

http://www.google.com/url?sa=t&rct=...URHahYl03U6J_tw&bvm=bv.80642063,d.aWw&cad=rja

I would be very interested to see a side by side comparison of EPA versus non in an output and emissions test.

 

[Whitespider]

Yes they are designed to pass EPA test procedures, but in doing so they also improve upon the old designs and improve efficiency.

By who's standard??
Improved efficiency of what?? Combustion efficiency?? So what?? That means nothing to the "rate" of heating output (i.e., BTUs per hour). Combustion efficiency is a measure of how much wood is consumed (converted to heat energy) over the entire burn cycle... not a measure of heat output.

I'm not going to discount that the new stoves work better just because they are EPA approved either.

I ain't discounting anything... I'm simply saying that an elitist stove ain't the be-all-to-end-all you're saying it is.
You're the one "discounting" that the smoke dragon may be a better choice for certain applications... I've acknowledged several times the elitist stove may be the better choice for certain applications.

Lets face it, you're basing your entire opinion on a sample size of one stove.

NO‼ I am not...
But let me ask you... what sample size (of both types) are you basing your opinion on??
Because, no matter how you slice it, that's all it is... your opinion‼
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[Cerran]

By who's standard??
Improved efficiency of what?? Combustion efficiency?? So what?? That means nothing to the "rate" of heating output (i.e., BTUs per hour). Combustion efficiency is a measure of how much wood is consumed (converted to heat energy) over the entire burn cycle... not a measure of heat output.


I ain't discounting anything... I'm simply saying that an elitist stove ain't the be-all-to-end-all you're saying it is.
You're the one "discounting" that the smoke dragon may be a better choice for certain applications... I've acknowledged several times the elitist stove may be the better choice for certain applications.


NO‼ I am not...
But let me ask you... what sample size (of both types) are you basing your opinion on??
Because, no matter how you slice it, that's all it is... your opinion‼
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Both improved combustion efficiency and heating efficiency. As for who's standard that would be under any testing method from ASME to CSA.

A older non-reburn stove is not going to be a better choice for almost any application unless you're trying to burn inefficiently or improperly.

(fyi calling it an "elitist" stove just demonstrates bias)

I'm basing my opinion upon the facts and experience with several stoves (7 I've helped replace so far) that I've helped family members and friends replace.

Also I have read the studies and have almost 20 years experience as a professional engineer with solid fuel combustion in boilers and wood energy systems

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CCUQFjAB&url=http://www.epa.gov/ttnchie1/conference/ei17/session4/houck.pdf&ei=xDeGVOSuAcOfyATZqYCwBQ&usg=AFQjCNE_Mu1qzuu1QZCg59UThuRIF6WESQ&sig2=-ZoUSCZttplhhELnsR7n1w&bvm=bv.80642063,d.aWw&cad=rja


http://www.google.com/url?sa=t&rct=...URHahYl03U6J_tw&bvm=bv.80642063,d.aWw&cad=rja

 

[Whitespider]

Both improved combustion efficiency and heating efficiency.

Show me the tests and numbers.
We've already been through that in this thread... there ain't no comparative testing or "proof" of improved heating efficiency, only combustion efficiency.

(fyi calling it an "elitist" stove just demonstrates bias)

Just as the term "smoke dragon" demonstrates the same bias... I'm just playin' along.

I'm basing my opinion upon the facts and experience with several stoves... family members... friends...

Yup, same here.
Admittedly some like the elitist stoves better than others. But almost to a man they "dislike" the same things (compared to the smoke dragon)...

1. During secondary combustion the heat output is difficult to control.
2. When the secondary shuts-down heat output is drastically reduced.
3. They haf'ta "fiddle" with the thing a lot more.
4. Excessive coal build-up during times of high heat demand.

In my opinion, that ain't "better"... or even an improvement‼

Also I have read the studies and have almost 20 years experience as a professional engineer...

Playin' the engineer card holds no weight with me.
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[Cerran]

Show me the tests and numbers.
We've already been through that in this thread... there ain't no comparative testing or "proof" of improved heating efficiency, only combustion efficiency.


Just as the term "smoke dragon" demonstrates the same bias... I'm just playin' along.


Yup, same here.
Admittedly some like the elitist stoves better than others. But almost to a man they "dislike" the same things (compared to the smoke dragon)...

1. During secondary combustion the heat output is difficult to control.
2. When the secondary shuts-down heat output is drastically reduced.
3. They haf'ta "fiddle" with the thing a lot more.
4. Excessive coal build-up during times of high heat demand.

In my opinion, that ain't "better"... or even an improvement‼


Playin' the engineer card holds no weight with me.
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Odd that that list is your same list of complaints about your particular stove. The claim that secondary combustion is hard to control heat output hasn't been the case with any stove I've helped install including:

Quadrafire 3100i
Englander 13NCL
Quadrafire Isle Royale
Kuma Sequoia
Blaze King Princess
Englander 30NC
PE Summit

All of the stoves seem to be easy to control during the peak of the fire when heat output is highest and none have experienced the excessive coal buildup you complain about. The only real complaint I've heard is the minimum turndown on the newer stoves is higher than their non-epa counterparts, but given the goal of emissions reductions this would be expected.

As for the lack of comparative proof, if you sort through the numbers it is there, the newer stoves have lower stack temps (better heating efficiency) and lower emissions indicating more complete combustion (better combustion efficiency).