IntensiFire? How does it work?

[aparker]

You're best bet would be to approach woodychain directly through his website. I believe that intensifire must be customized for each stove.

As far as modifying the stove, can you give more information about the stove itself? I assume the owner would frown on any permanent modifications so everything would need to be reversible. Still, there may be some improvements that could be applied. It would be good to start a new thread if you wish to discuss modifications, other than intensifire.

[torch]

I looked at his website. Didn't see anything about the IntensiFire. Tried the search function, it got no results. So I figured I'd ask here, since this is where he invited questions. (Besides, he might be interested to know that this discussion of patent research turned into a possible sales lead . Assuming that this thing is a real product and not just vapourware.)

As for the woodstove, like I said, it's a big steel box. I don't have the exact dimensions here at my house, but it's maybe 2' deep and I think deeper than it is wide. It has a step up at the rear, where my old Fisher had baffles, and the flue exits from the rear from that raised section. A hinged front door with intake dampers. There is no fire brick lining. There is no ash pan below. There is no damper on the flue. It sits on 4 legs that in turn are sitting on cinder blocks.

The chimney is new, only because the Fire Department ordered the landlord to replace the old one last spring after the fire. (The old flue exited horizontally, into the cinder block wall. Outside the chimney dropped down into an old wheel rim set in concrete, which served to "join" the horizontal flue to the chimney. )  The new chimney was properly installed by a WETT-certified contractor, but the woodstove is not yet connected to the chimney.

The landlord doesn't care what my son does in the way of improvements about the place, so long as it doesn't cost him any money.

[aparker]

Well, I guess woodychain has made some adjustments since I last visited his website. Too bad. I was looking forward to seeing how he did marketing intensifire. Hopefully, he can respond and put our minds at ease.

You could always try contacting intensifire in New Zealand directly (I think that the purchase price through them would be about $375 US, including shipping, at today's exchange rate, but there would no doubt be some additional fees from the banks).

So, could you fit a batch box inside the big steel box? There have been some very clever adaptations of the basic batchbox. Even just lining the combustion chamber with insulative firebrick (or reasonable facsimile) could improve things. Would there be space in the room for a bell or series of bells? I am thinking of something like Dragon Heaters' Derrick Build Masonry Heater.

[torch]

Well you've given me some more terms to google. Until I find out what batch boxes and bells are, I can't answer your questions intelligently.

[torch]

Ok, I'm back, following a short education. Thanks for those terms, they really helped me learn how much it is that I don't know. The funny thing is that I'm a big fan of Samuel Clemens' body of work, and as I was realizing how similar bells are to some old concepts, I rediscovered his description of old Czarist-era Russian fireplace efficiency. "What's old is new again", I suppose.

I really like that bell idea. I'm not sure if there is enough vertical height available for the Dragon Heater's designs. This old farmhouse has about 6-1/2' to the wood joists in the basement where the furnace is and only slightly more upstairs in the living areas. I'm also not sure about local (Ontario) building code requirements with regards to trying to direct flue gasses downwards. What little training I have (I'm a career company officer with a large metropolitan FD) always stressed that flues should go up.

20 years ago, the Building Code Commission ruled a very similar "high thermal mass masonry heater" design to be illegal (see: www.mah.gov.on.ca/Page8224.aspx ). One of the reasons was the proposed flue design. The current building code has changed so the section numbering is different, but the identical phrasing is still present in the current code:

9.21.2.3. Inclined Chimney Flues

(1) Chimney flues shall not be inclined more than 45° to the vertical

Now, I am far from an expert on this, but on the surface it appears the Ontario Building Code has not yet caught up to current practice or technology. That said, the BCC did soften their stance somewhat in 2001, allowing a similar appeal on the condition that the design and installation was approved by a mechanical engineer (see: www.mah.gov.on.ca/Asset7733.aspx ) (The description in this one sounds very very similar to the Dragon Heater's design, if I understand the concept of bells properly).

Given that the local FD has already issued a compliance order regarding the chimney, and assuming their level of training is similar to my own, I don't think bells will fly here without a lot of very expensive legal wrangling. A shame.

OTOH, I have received virtually no training about woodstove design, the Code merely references a mysterious "CAN/CSA" standard that you can't read unless you buy it, and there was no order relating to the stove itself anyway . So lining it with firebrick and adding something like the IntensiFire are not likely to appear on radar.

If anyone has more up-to-date information about any of the above, I'd love to hear it!

[woodychain]

Sorry for the delays in getting back to you concerning the Intenifire. We did work togetherwith Jason when he stayed at my place for a few months last Fall and used my shop/lab to build some prototypes and help me understand how it works, what needs improvements and how is the best way to market the Intensifire. For you do it yourselfers, I'm sorry, too much too go wrong and too way toooooo much liability. The only way I would feel comfortable providing the Intensifier to the general public would be working together with manufactures incorporating the technology into improving the combustion efficiency of existing product lines like Outdoor Wood Boilers which are currently in the EPA's cross-hairs. We looked at several other products and ideas before I came to the conclusion I now have. We tried converting a wood cookstove which we could never get to work right and could not control the oven, so that was a bust. We'll have to design that from scratch to make it work properly.
Next we installed an Intensifire in a Prefab Zero Clearance Heatilator Fireplace which is not very efficient and did not throw much heat either. The Intensifire does what its name says, INTENSIFY!!! the fireplace got so hot the top of the fireplace was glowing red hot and the tempered glass doors exploded into a million pieces from the heat. That was enough for me to understand the dangers of installing the Intensifire in a product that has a UL ULC listing for clearances to combustibles. That means all UL ULC listings are now void and the product is now a huge liability magnate just looking for a hungry law firm to latch on to it......no thank you my Kiwi friends, in North America we have a sue happy culture looking for a ride of the gravy train....
Next we converted an old Security BIS Panorama Zero Clearance fireplace that did prove to be very promising as it was built heavy enough to take the heat. I would build a fireplace from scratch that was designed specifically for the Intensifire and would be UL and ULC tested so I can offer them to the general public. That idea is now on the back burner as we are currently focused on introducing our own line of wood cookstoves to add to the Obadiah's line of woodstoves. Next will be a fireplace line to compliment or current line of masonry fireplace cookstove conversion units that are unique in they allow folks to convert existing masonry fireplaces quickly and easily themselves without the need to install a fireplace insert and new SS liner to meet UL 1777. They can now enjoy their fireplace with more heat and less wood, they can even cook inside their fireplace with our crane holder which holds a dutch oven or use the adjustable grill.
We also converted a Woodmaster LT90 that was donated to us by Woodmaster to see what we could make happen with it. That project is currently ongoing and confidential, other than what I have shared on one of my websites, cookstoves.net/articles/cookstove-basics/intensifire-clean-burning-tech-improve-stove/
Hope this helps fill in gaps since last time I visited here.

[Vince]

I just wanted
As reading this link cookstoves.net/articles/cookstove-basics/intensifire-clean-burning-tech-improve-stove/ and as a NZER myself find some points in that a tile to be falacious. Like the bit about the boat being rammed unprovoked. Watch the actual footage and the story is different, As were the court findgs. So it makes me worry about other statements of this invention/patent.

[drooster]

Vince ... I didn't see anything about a boat ... 'cos this is about stoves (and I don't click most videos).
Do yo have any details about false claims to do with downdraught/secondary burn?

[firemasternz]

Apr 25, 2016 12:20:27 GMT -8 woodychain said:

"Next we installed an Intensifire in a Prefab Zero Clearance Heatilator Fireplace which is not very efficient and did not throw much heat either. The Intensifire does what its name says, INTENSIFY!!! the fireplace got so hot the top of the fireplace was glowing red hot and the tempered glass doors exploded into a million pieces from the heat. That was enough for me to understand the dangers of installing the Intensifire in a product that has a UL ULC listing for clearances to combustibles. That means all UL ULC listings are now void and the product is now a huge liability magnate just looking for a hungry law firm to latch on to it......no thank you my Kiwi friends, in North America we have a sue happy culture looking for a ride of the gravy train...."

Jason here, inventor of the IntensiFire. I just want to post here to clear up a misconcepton regarding the broken glass. The Heatilator Woody refers to is a fireplace, not a woodstove. It isn't airtight, the doors are just bifold. It doesn't produce a lot of heat either, so the glass is only required to be tempered rather than the more expensive ceramic glass found in Woodstove doors. The glass panel that exploded (one of four panels) was clearly not tempered glass, but ordinary window glass. The way you can tell is how it breaks, tempered glass will shatter into lots of regular sized pieces about a 1/4" in dimension. The breakage Woody refers to was what you would expect from a normal house window, a mix of large pieces and fine shards. 

Yes the IntensiFire gets hot, but not enough to worry ceramic stove glass. 

Also the deal with Woody didn't quite get off the ground. If you an IntensiFire get in touch with me directly please. 

Recent news is that the IntensiFire retrofit has been approved for use in Chile. Check that out on The IntensiFire facebook page. 

I hope you are all well. And the fellow commenting on the maritime affair should go to the trouble of downloading the report from Maritime New Zealand, the authority that investigated it. I won't be commenting further on that matter here. 

[kaiateic]

Thank you Stoker for summarising the thread so well. (See the very first post in the thread.) It is unfortunate that it went off the rails, like it did. Now, few people will read through it. 

Well, I hope some people will look at this thread because I would like to revisit the technical discussion.

Please refer to the marked up drawing in the following google doc.

docs.google.com/document/d/1E_SPF2QUqc031NizKhhyVTIg7qdPc8pdM0A5-tg_TJQ/edit?usp=sharing


The IntensiFire patent describes the secondary combustion zone (5), a flue (11) that extends down into the firebox and an annulus (16) around the flue. According to the patent, the airflow in the annulus is downward (17).


I believe this is wrong. The part of the flue that extends into the firebox is the hottest surface in the apparatus. Any air in contact with it will want to rise rather than fall. Thus, a circulation ( shown in red ) is induced in the firebox where the air rises in the annulus (and maybe even just outside the annulus) and falls near the (cold) exterior walls of the firebox and, in particular, near the primary (cold) air intake (15).


Secondary combustion will take place in the annulus (and maybe even just outside the annulus) at very high temperatures (since there are no cold surfaces to cool it down). After combustion, air exits the annulus and heat is released to the outside surfaces of the firebox.


One interesting thing to note is that this turbulence is not created by the chimney draft, but rather by the temperature difference between the flue and the outside of the firebox.
 

What do you think? Does this make sense?

[Rusticus]

kaiateic - Don't forget that the lower end of the Intensifier assembly is intended to be immersed in the bed of hot coals; that's what makes the garden variety woodstove into a "downdrafter" style of stove and provides the secondary burn conditions, pulling smoke through the hot coal bed to "crack" it, then mix it with fresh preheated secondary air. Thus, air and smoke will be entrained by the draft of the stack gasses as they pass over the lower edge of the annular tube, submerged within the coal bed. It's difficult for me to imagine the combustion conditions under which the stack draft wouldn't cause the flow in the annular space to be in the direction Mr. Stewart indicates in his patent. Only if the flow of stack gasses in the inner pipe were completely separated from the gasses outside of the pipe does the opposite flow seem likely to occur (if, for example, the stack gasses were pulled from under the grate, while the firebox gasses could enter the bottom of the annulus).

The New Zealand version of Mr. Stewart's patent illustrates one embodiment having a separate draft for secondary air through the bottom of the fire box, with the smoke and combustion gases pulled through the coal bed. The two gas streams then mix at the bottom of the Intensifier assembly.

Regulating the flow through the annular space to optimize secondary combustion might be tricky. The alternative form shown in the NZ patent might make this tuning process a bit easier (i.e. some form of damper), though the secondary air would enjoy very little preheating as illustrated in the patent drawing.

As I understand it, Mr. Chain effectively abandoned the retrofit market in the US, due in part to the difficulty of and time required for tuning the device to individual stove models and installations (liability concerns also figured in to his decision). However, if you are motivated, that shouldn't dissuade you from such an investment in tinkering! If the operator can adjust the secondary air from the exterior, then most or all of this fiddling could be shifted off an installer's/vendor's shoulders. Wood stoves being what they are, most of us are accustomed to monkeying with our stoves, anyway. I'd definitely try to find a way to make the secondary combustion mixture externally adjustable.

I am trying to suss out an effective way of adding secondary combustion to my dad's old Daka wood burner (probably a 311 or 411 - it has the over fire door draft spinner), so I am very interested in Mr. Stewart's approach, even if it cannot be directly applied on this stove due to existing internal baffles, etc.

[joseph]

It seems that many of the issues with the IntensiFire is that it was intended as a retrofit. So, basically no one is interested:
Manufacturers only want to sell new stoves, retailers and installers don't want the liability, and do-it-yourselfers won't spend $500 for it.

Also, any "one size fits all" type of retrofit is going to require compromises. So, a DIY person looking to improve a particular stove or a company looking to engineer a new stove is probably not wanting a "one size fits all" solution but one that fits their specific need.

It seems that this device was made the size and shape of a stovepipe to enable selling it as a quick retrofit, but there may be a better way to accomplish the goal (secondary combustion of woodgas, etc) if you aren't trying to sell a quick retrofit.