Jason Stewart

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since Sep 10, 2013
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Recent posts by Jason Stewart

Interesting topic. It has taken me back to a few places, and made me consider some new ones.

Perhaps you have some confirmation bias creeping in Donald But I will say I like your approach, before I provide some critique.

Some of the answers you are looking for are. I believe, in places you haven't yet looked. The Woodstove Decathlon had a rocket heater in the mix, the cool Walker Stove, and this was tested alongside a range of other stoves.

The New Zealand method for testing stoves is done in a calorific room, all the energy entering or leaving the room is measured. So changing the useable calorific value of the wood would not change the efficiency of the stove in this test. This alone might cause you to re-evaluate some calculations and inferences you are making. There is one model stove sold in both the USA and New Zealand that tests as 78.5% using, I assume, the British Standard, and 72% with AS/NZS 4012. Am I right in assuming the British Standard uses the stack loss method?

In regard to the reduction in efficiency of water, calcs I did at one point showed the difference between green wood at 50%, and air dry at 20%, is only 6%. This was working out the BTU's to boil water. Also, if you assign a greater calorific value to wood, then the percentage used to boil off the water reduces.

Can I assume that a typical Rocket stove is a lower overall output, and therefore a lower mass of wood used? If so then there is a negative side to the Law of Mass Action to join your positive ones

The second law of thermodynamic may work against some mass heaters. A very hot box made from steel or cast iron gives off heat a lot faster than a warm mass. There are other factors at play arising from this law here that I won't go into here.

FYI the IntensiFire saw 1635°F 2' up the flue, and CO levels started rising exponentially once that temperature dropped below 1380°F. That looks to support the ignition temperature figures published. Note that despite these high flue temperatures the IntensiFire outranked two stoves for efficiency in the Decathlon that have been measured at 80 & 82% (also I assume using the British Standard).
4 years ago
Lenny an interesting response for me to consider.

There are generally two types of question I receive about my product. The first is would The IntensiFire work well in my stove? To which my response is usually a repeat of the laboratory report commented on earlier in this thread, an increase in the heat delivered into your house from every piece of wood you put in your fire from around 50% to about 75%. If they haven't sent me the make and model (which isn't necessarily determinative) I then ask for photographs or drawings, particularly of the inside around the flue exit area.

The second and very common query I get asks "I can't see any information on how it fits to my stove". With the three winters I have been selling these for in New Zealand my interpretation of this question is "I can't see how I can build one for myself". It also contains the presumption that the questioner has the ability to both understand my technology to successfully duplicate it and to know it is possible to convert their stove. I find this type of person usually wastes my time in email exchanges that have even gone to the extreme of some people asking me for plans or they won't buy it! It is actually very simple and thus easy to copy, but not easy to copy it right. I don't want lots of bad copies giving the technology a bad reputation, which has actually happened to me here in New Zealand in a small way.

The question to you Lenny is why wouldn't you want your stove to be 50% more efficient? Some further questions. How old is your stove, or how long has it been inefficient and polluting? How long will your stove last? And do you intend to continue to let it be polluting and inefficient for the rest of its life?

The difficulty I face as the inventor is actually making this affordable but at the same time making it fit the many different models of stove out there. I realised three years ago when I invented this technology its significance that other people would want it. I have continued, unpaid and in debt to date, to solve the problems associated with it while at the same time fighting people that would take of my time and effort for free.

The other question is do you want me to continue to develop this technology towards what at this points seems revolutionary in terms of emissions? Most electricity doesn't even come without an environmental cost so the only sustainable fuel better than zero emission wood is passive solar. Well that I can think of right now. I can't do this unpaid forever.

Yes the technology will fit your stove Lenny but it isn't an off the shelf solution. If you are interested then please PM me some drawings of the internal dimension of the internal structure of the stove. There will have to be custom made components and I have to work out the best way to have these made for you.

BTW I am only just back in New Zealand to finally find out that the challenge of making the Wood Stove Design Challenge pushed me beyond my ability to cope. I didn't realise it but I contracted pneumonia half way through the competition and still have it. Looking forward to some R&R to recover.

PS. There was also a later correction on the rankings. IntensiFire placed 2nd= for affordability and 3rd for innovation.

6 years ago
Hi all,

well I am pleased to inform you all that I won an award at the Wood Stove Design Challenge for the most affordable clean burning technology. It has been a mission doing this on a budget and that probably cost me a better result as I tried to tune a monster Treemont stove with a 60 lb fuel load for the tests. I didn't get a rest so am exhausted from the 7 10 hr + days tuning the stove but a late result with an emissions test(that couldn't really be considered for the results) was rather satisfying as it backed up the zero emission capability of The IntensiFire.

7 years ago

Leila Rich wrote:I'm always pleased to see NZers around here
I know nothing about this fire stuff, and apologies if the info's on your site.
My folks are building a new house on the West Coast of the South Island, and the plan to put their old Shacklock woodburning stove/oven in there.
The thing is pretty useless actually; and considering I've used some great ones, it's likely to be the flue/installation/draw etc.
But that's another issue...
Anyway, is your kit suitable for those kind of stoves?
It's pretty warm down there and getting more heat's not a major factor, but the emissions/efficiency certainly is!



Hi Leila,

nice place for your parents to be although they can't mind the rain in those parts. Yes it is possible to retrofit and old range although it wouldn't be off the shelf. It would take a custom engineering to make it fit if they have access to someone with a workshop that could do that. Get them to contact me through my website if you like although my head is going to be around the "Design Challenge" for the next couple of months.
7 years ago
Thanks for the welcome guys. Some good input, ideas and an invitation to chew over.

Dale I would love to license it and then be able to focus solely on R&D, hopefully the Design Challenge will offer up an opportunity or two.

Bill I will discuss that offer of yours with my father as he is coming with me. Actually he is my sponsor in this and has stumped up the patent costs to date. Depending on how things pan out with the stove I hopefully have lined up then I may have a few days before the setup day at the National Mall. We have allowed some time for a bit of sightseeing afterward with the Blueridge Parkway in our sights. I haven't traveled internationally that much, and not at all to America, so I am keen to get a good look around.
7 years ago
A friend was searching for my website today and this site come up on google's first page. I will take the opportunity to answer the question posed in the thread, particularly by Dale.

First up it is a retrofit for a stove, not a stove itself. Although I am keen to see my new designs in production when the means becomes available to me.

As per the "History" tab on the website it has been tested by an independent laboratory in a calorific room with a sample train on the stack. The procedure is NZS 4012 & 4013. The test was only on the low setting and increased the efficiency from 52% to 75%. Those figures are on a wet basis, to get the equivalent dry basis figure for the equivalent USA test add around 7% to those figures. Output was lifted from 4.6Kw to 6.5kw although it peaked at 12Kw while warming up. Emissions were down from 4.5 g/hr to 3.5 g/hr. The test was a learning experience for me and I went home and made it better, particularly on the emissions side.

On the issue of legality, going by the local example in New Zealand it falls between the cracks because no legislator or bureaucrat thought it could be done. It can't be made legal, but it isn't illegal either. Insurance is an issue but there are simple methods to make sure it won't burn your house down. Keep in mind that safety tests are also known as "clearance tests" and are for the most part about the distance between the appliance and your walls to make sure they don't catch fire. They are also a worst case of abuse type scenario not about every day use. I believe a sensible person can work a solution to the issue I have been lobbying for two years now and there is just a brick wall.

Freight: I will freight to the US for the prices advertised. Freight is expensive, probably $80+ NZD but the bigger issue for me is that ground shipping isn't available and air freight doesn't really fit the green image of a product like this. I might have to wear that in the short term with the greater picture in view so I am busy designing out some of the excess weight. If you know of someone looking for a business opportunity, or simply a manufacturing and distribution role for the US send them my way.

Cost: I hope that one day mass production will bring this down and allow me to make further improvement to useability, but a distribution cost has to be factored in. If you buy a cheap second hand stove you will still want The IntensiFire to improve its performance

Yes I am a one man band.

I am a designer and inventor not a businessman, hopefully things will go my way. My hope is that one day I can commit to permaculture on my own block of land. I brew beer from grain in my spare time and got my hands dirty in the weekend planting hop rhizomes. A good little journey because I found out about, then executed, willow water.

Because it isn't a successful venture just yet I deliberately hold back on giving away too much technical information away, even the website information was going beyond my comfort zone. Essentially it is an internal flue extension that turns it into a downdraft burner. When I can draw a comfortable income then I will consider open sourcing it, dreams of riches are not what motivates me. As for how it works I do have some design ideas that I believe are an advance on conventional design, and I will likely advance things further. I had to apply for a second patent this year to cover additional ideas.

Dale your fire advice is excellent and applies to The IntensiFire as well. It gets very hot and I recorded 1100°C before the wires melted out of the thermocouple, hence the name. Masonry stoves are a place I will go one day but in the US alone there are 8 million old stoves to fix up first!

Yes I was at the helm of the Ady Gil when we were rammed by the Shonan Maru II. I had previously spend 10 weeks as a volunteer on Earthrace in the role of Engineer as she toured around New Zealand. I got a last minute call as replacement for the Antarctica campaign. A 25 minute close encounter with three humpbacks on that trip was absolutely amazing. You can find a short clip of that on Animal Planet. Pete Bethune is still a close friend.

I hope some of you come to see me at the Wood Stove Design Challenge in Washington DC, November 16-19th.

Regards

Jason
7 years ago