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Wood stove hack-secondary burn tubes added

Nonprophet

Nonprophet

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The Elm looks interesting.

The secondary air tubes do not appear to be in the main air flow channel which is a red flag IMO.

Most stoves today are using an 'air wash' system to keep the glass clean and I don't see that in this stove either.

Still an interesting stove and quite good looking!

Any idea on asking price?

I'm some concerns about parts should something happen to what looks like a very small company.
In his pics, the secondary air tubes are located just under the large interior baffle--with the air "jet holes" pointed towards the underside of the baffle where the smoke and gasses accumulate. In his videos, he's clearly getting secondary burn, so it must be working to at least some degree.

You're right in that I don't see a built in airwash system to keep the glass clean, however I've spoken with a few other Elm Stove owners and they all say the the glass stays clean......so maybe there's something going on there we're not aware of.

Another point of interest is that the glass widow is actually a Pyrex pie plate that can be bought at most stores for about $7.............

I'm with you on the parts thing, however there does seem to be a VERY loyal following for these stoves and he seems to have just about all the parts available. They have a well deserved reputation for being very well built and easy to use and maintain. I especially like the fact that because they're round there are no welds to crack, no high-stress corners etc. Another added benefit of the barrel design is that if you load up the stove for an overnight burn, the splits naturally roll into the center (on top of the coals) as the fire burns......

I saw a guy on another forum who just bought a brand new one. It was a relatively fancy model with the secondary air tubes, nickel plated Elm logo and ash pan, side warming racks, etc. He paid $1,750 for his. Smaller models and ones with less bling are also available, but I don't know the cost on those.

NP
 
Haywire Haywood

Haywire Haywood

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I think it's a very attractive stove, nice departure from the usual box. The only drawbacks I see are that it's very deep front to back with it's 24" capacity, so it wouldn't be very good for the space challenged to install and no ash pan. On the other hand, loading north/south like that would make filling it easy.

Ian
 
Nonprophet

Nonprophet

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I think it's a very attractive stove, nice departure from the usual box. The only drawbacks I see are that it's very deep front to back with it's 24" capacity, so it wouldn't be very good for the space challenged to install and no ash pan. On the other hand, loading north/south like that would make filling it easy.

Ian
Yeah, they're not an ideal stove for the space-challenged, that's for sure! They also don't have any heat shields built in to them, so the clearances aren't so great, but, if you have a spot for them they sure are great stoves!

There's also a smaller 18" model available, as well as a larger 36" model.


NP
 
kees53

kees53

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secondary combustion

Hi all

I am new here, and I fall in this house with the following.

secondary combustion is not as easy then some here predent.

I am busy with my own woodstove in holland to make a insert.

I have some calculations done and it is that a baffle is the best way one of 1.6 sq ft for preheating and 1.5 sq ft for second preheating so it is capable to get enough heat without a very big fire,

You van find a lot in the google search on patents.

I have a french woodstove with a lot of room to make it working, it will be some weeks to complete.

I have seen a couple of pictures with a baffle this has only preheating above the fire, but you need also a vertical baffle behind the fire to help make the air hot.

Some have used pipes I am not very impressed of that because you have to make the fire very hot to let it work.

http://www.cham.co.uk/phoenics/d_polis/d_applic/d_comb/secomb/y263.htm

http://mb-soft.com/juca/print/315.html

and my burn with a smal pipe who don,t work well only when heated heavely.



These link from your site

http://www.arboristsite.com/showthread.php?t=37370&highlight=secondary+burn+tubes

That is the best way, and can be better if the baffle is extended with a backplate of 1.6 sq ft.

Be the way whare is the place this pictures is discussed, because I will use this in my own stove, it is nice and the best way, the hotter the secondary air the better it wil be.

greetz from holland.
 
kees53

kees53

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What is CFM I am dutch so explane.

you need a survace of 1.6 sq feet (bigger is better) for the vertikal baffle and 1.5 sq feet for the upper baffle.

this wil heat the air to more than 500 F.

info on the links.

greetz.
 
Haywire Haywood

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That .uk site was interesting. It looks like an add-on secondary burner. I read something in the last few days about ideally the secondary burn would be a separate chamber so that the heat from the sec. burn wouldn't accelerate primary combustion.

I can't really take the Juca site too seriously. I thought they were actually out of business but I found a current price list there which surprised me. If they would update their site with current pictures and some new web design, it would come across as little more believable. As it is, it looks like they scanned their info in from 1970s brochures and not much more.

Ian
 
Haywire Haywood

Haywire Haywood

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What is CFM I am dutch so explane.

you need a surface of 1.6 sq feet (bigger is better) for the vertikal baffle and 1.5 sq feet for the upper baffle.

this wil heat the air to more than 500 F.

info on the links.

greetz.
Cubic Feet per Minute. A measurement of air flow volume. The .uk site said that for their design you would need the same amount as you have for primary combustion.

Ian
 
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kees53

kees53

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thanks

I read somewhere that secondary air has to be 3 to 5 times of primary, best is
to make it adjustable with holes in the back of the stove like my plans are..

if you burn wood then you have to shut the primary air, only for coals it is needed, when you start then you need primary, after heating shut it down.

I did this al the time and it works the best, and only for modern stoves with secondary air not for old smoke dragons these need a insert.

some patents here in pdf files so we can learn.
 
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sesmith

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No problems. I did the stove modification in Jan. '08. The black pipe shows no signs of warping or breakdown in any way. The modification did not damage the stove in any way. It did totally change the way the stove burns, and there is much less smoke coming from the old beast than used to. I do have to be a little more careful as it would be easier to overfire the stove now. As far as wood use goes, I'm kind of unsure at this point. I used 6.3 cords last year and 6.25 cords the year before. I can say though, that I started burning wood earlier last year than the year before, and that last year was quite a bit colder than the year before. So my gut feeling is that it is more efficient, but I don't have a good feeling for how much more it might be.
Just wanted to drag this thread out of mothballs to say I finally did some calculations. The modification to the stove increased it's efficiency by about 11%. That was the # after I normalized 1 heating season to the other by taking into consideration the difference in heating degree days between the 2 years, and taking into consideration that I did the modification during the heating season, so it wasn't in all season. Also had to factor in the heating oil I used both years. I couldn't make any comparisons this year, though cause I added a solar air heater into the mix (that, by the way, will be worth 26% or a little more, of my heat).
 
demographic

demographic

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Just wanted to drag this thread out of mothballs to say I finally did some calculations. The modification to the stove increased it's efficiency by about 11%. That was the # after I normalized 1 heating season to the other by taking into consideration the difference in heating degree days between the 2 years, and taking into consideration that I did the modification during the heating season, so it wasn't in all season. Also had to factor in the heating oil I used both years. I couldn't make any comparisons this year, though cause I added a solar air heater into the mix (that, by the way, will be worth 26% or a little more, of my heat).
Solar air heater? We need pictures, and maybe even a different thread about it.

I'm interested now.
 
sesmith

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Solar air heater? We need pictures, and maybe even a different thread about it.

I'm interested now.
How about a link instead. It's the larger of the 2 here. Scott also put in some performance data I collected on mine toward the bottom of the page:

http://www.n3fjp.com/solar/solarhotair.htm

For lots of other solar DIY info check out the following link:

http://www.builditsolar.com/index.htm

This site is kind of the bible of DIY solar. The 2 downspout collectors referenced in the above link are also buried somewhere in the hot air collector page here too.

As far as another thread on the solar stuff, maybe arborsite should have an alternative energy forum where subjects like, solar, wood gasification, wind, insulation and energy conservation, hydroelectric, etc could live. ********** has something like this. They call the "green forum". There's a lot more activity over here, and it would be better to keep it geared more toward energy and heating, and not "what are you going to plant in your organic garden today" kind of thing. (Just my opinion, though).
 
romulus

romulus

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Exchange of ideas needed

Hi to all,

I've asked in another thread, however, no single sole has replied.

I have a Franklin fire box stove, so the doors are not sealed and even may not be sealed since the air intake for burning cannot do for the small openings at the bottom part of the doors. At the top part of the doors, one of the four doors has even a thinner wall at the end to let more air in for combustion.

In order to try the secondary combustion idea, I would have to introduce a vertical baffles to keep the temps high enough (without refractory bricks?!) and perhaps a forcing air blower, say, as produced by Secoh.

Can anybody help me with a piece of advice how to arrange a horizontal baffle with holes instead of tubes. I think the Franklin stove has already an improvised secondary combustion camera, an additional baffle plate with holes added would however better its functioning. But I do not know how to introduce preheated air above the horizontal baffle with holes. Several pics from this website didn't show how to, alas.

I can imagine the way some Tempwood stoves take in air from outside through 2 inlets in the top plate of the stove, so I could put 2 small tubes through the fume output pipe -- for outside air input --- even without any blower. -

Or else, I'd weld a hearth box insert of stainless steel to the available stove with a gap of about 1 inch to the walls of the stove inside, plate-like, with holes above for preheated air supply. I hope that air is a bad warmth conductor, and the refractory brick insulation lining would then not be needed. Has anyone experienced working with plate-like air ducts instead of tubes without lining?

Thanks
 
sesmith

sesmith

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Hi to all,


I have a Franklin fire box stove, so the doors are not sealed and even may not be sealed since the air intake for burning cannot do for the small openings at the bottom part of the doors. At the top part of the doors, one of the four doors has even a thinner wall at the end to let more air in for combustion.

If the stove is not airtight, I can't imagine any benefit of adding secondary air. The problem with a non-airtight stove is that you can't completely control the amount of air coming in, so there would be no need to add additional secondary air. A secondary air system would also not provide any air for combustion if the path of least resistance is a leak elsewhere in the stove.
 
connollyr123456

connollyr123456

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Treemont WoodStove

I have a treemont unit that I am thinking of adding secondary pipes to the unit to increase it efficiency. Is there more on the correct installation of secondary tubes?
 

pook

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silly 2me= intake pipes should be on bottom so to keep the bottom of the load somewhat cooled & not burning
read "nature of fire" blog in my sig.
 
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