Ernie Wisner

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since Oct 16, 2009
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Recent posts by Ernie Wisner

Once again we have been asked to weigh in on this subject

I will try to be somewhat brief.
The only metal I know of that will handle the temperature and corrosive gasses in the combustion unit of an RMH for very long is toungston.
Every SS and high temperature steel degrades very quickly at 1200 to 3000 degree's as is found in the  burn unit of a well built RMH.

Test after test conferms this. The metalergy conferms this the chemistry conferms this.

No matter the metal except the one mentioned burns out in ( for an RMH) a very short timeframe. Most will last a few months  some might last a year or two.

At this point I could give you all the sciannce and literature to support my claim but you can find it just as well as I can. So please do so.
The only way to protect the metallic components from failing is to place a barrier of masonry between the fire and the steel. And this only works for a short time since the steel is inside the insulation layer of the burn unit. The metals simply cannot handle the sustained temperature's.

I know it is easy to weld up a burn tunnel and heat riser, I KNOW it looks like it will work fine because all those dirty burning free standing stoves and grills work just fine. But the RMH isn't a Webber or a free standing wood stove with a 5 year life cycle. An RMH is designed to last for more than 100 years with as little maintenance as possible in its life time.

Some folks think that all of these manufactured materials must be good because they must meet industry specifications. The problem is many don't look at how they meet industry specifications. I have never seen a primary boiler that was not lined with some sort of masonry unless it was water jacketed and all of those units either burn dirty or automatically reduce temps when the pressures get high.

Those not lined are also as a rule gas or diesel fired and the chamber is very small with a heat exchanger set up to ensure the temperature never goes a over the boiling point of water.
In those systems nothing  ever gets red hot unless it is some bit of easily replaced sheet stock.

Someone is going to point out founderies that use cast iron crucibles to melt various materials. Yes they do and those cast iron vessels are very very thick and never get exposed to temps above the melting point of the cast iron.
Those Crucibles also are never exposed to actual fire either. Instead a couple of electrodes are put in that arc between And melt the materials. Not to mention   most steel's melt at a far lower temp than cast.
Even with all of this founderies replace crucibles regelerly.

To sum up you can find all the info on what steel will handle, what corrosion resistants it has at what temperature's, how long it can last in a reducing atmosphere, ECT. None of them beat a brick for durability in the environment we are building in an RMH.

There are lots of other problems with steel in the heat but I am limiting things to this one subject.

You are building a stove that has a lifetime steel's lifetime is much shorter in sustained high temperature. So unless you want to replace heat risers and burn tunnel's just about every year steel is a bad choice.

If you can afford an 8 inch toungston heat riser and burn tunnel more power to you, congratulations you have so much money you could use it as fuel..

Some few of you are boiling because all these folks are telling you what to do some have gotten angry enough to write a publication that you don't need to listen to any one on this subject and can have it all YOUR way. You can  but don't expect the folks who are dedicated to making the very best and longest lasting stove possible to be very forgiving when you start talking about how the RMH you built isn't performing up to snuff..

Any way thanks for reading.
7 years ago

the harvesters he designed might work but it is not going to do a darn bit of good unless the plastic can be disposed of. we have enough fleets that we could use this to provide the fuel to clean it up. problem i have seen in all of these schema is the end game. his idea was to bale it up and put it on ships, much of that plastic is from ships dumping recycling over the side because we bale it up and try to send it to china or africa to be reprocessed. price per ton drops and they toss it overboard. turning it into oil again on ship board operating the ship on the plastic makes more sense. IMO getting the fleets to go out and drag up the plastic that is far deeper converting it to fuel and ending the making of plastic with petroleum would be the better idea. there are lots of plant derived oils that arent toxins and nature knows how to deal with.

the other weakness in this is depth; the skimmer only works on the surface but the gyre's are a thousand feet or more deep. that also need to be dealt with, plastic microbeads and the broken down plastic has far nastier effects long tern than just the big stuff. ah well we will continue to throw money at it without fixing anything till we choke the might actually adopt a long term detailed solution.

8 years ago
the free radicals are not good for your plants, co2 concentrations or not. and those in several cases don't recombine in the heat but after the exhaust.

testing: we have discussed putting the protocol funding as a stretch goal for our book kickstarter.

Well we knew this was coming and its here; I don't know how to answer this guy because he is asking for lab results that none of us can afford to pay for at this time if we are dedicated to keeping this in the open market. the only way to satisfy this guy is to become a mainstream commercial concern. with loans and the rest of the trimmings.

I say we put out the information we have from as many sources as we have and why we don't want this going to the commercial world. Erica has a couple grad students that have worked on this in school labs and maybe we can go that way. I do still want to take it to the testing lab in beaverton for testing and its gonna cost us. frankly i suspect it will again be Us that puts up the money out of our little budgets for the testing. Are we all ready to do that? its gonna make several of us live on a shoestring for a while but if we pool the money we can get omni labs to do the test. I suspect the next part of this discussion will be what models we want get tested. I (as i am sure is obvious) want to get the basic brick RMH tested. I would suggest we test a castable and the batch box. however peter and i need to get together and make the batch box a bit smaller so i feel comfortable putting it into a normal house. not to mention that its not been tested in use for a year.

IMO the community needs to discuss this and make a decision on the Core tech. spin offs are fine to go private but I personally dont want to see this tech locked up by some box stove company that wants to remove the competition. This will happen if we break, it's the way business is done these days.

We have all shared everything to keep our development going but none of us have been funded to do R&D! we have done it with our own money We owe no debt to anyone and frankly i like it this way.

I would suggest go look at existing RMH's or put the money where the mouth is, because we have all done that. How much more open can we be? All of the info is out there for all to see. we have not hidden anything other than (with good reason) what we are currently developing. this is not like building some new portable dodad that you can stuff into a box and ship it off to the lab.

Anyhow thats my opinion and would like to hear what everyone else has in mind. we should also get a few of the other movers and shakers in on this discussion. its much more important than just a few can decide.

hmm in other news how the hell are we going to get temp readings in the hottest parts of the stove with it fully built? we are irrigating bricks and vitrifying clay. but so far we haven't any hard temp data (well we do but folks want to see numbers in the assumption they understand what the numbers are saying rather than looking at the physical evidence). Alright i have said enough
thanks all
9 years ago
So now i am logged in with my OWN account
What do folks think?
10 years ago
hi Karl yes its OK to let the prior course dry completely. and yes when you start working on it again you want to wet it and slip it so you get a really good bond. it also works to make sure your later courses are keyed into those holes to make a mechanical bond as well as a material bond.
11 years ago
Well for me your first attempt failed so i think you might need to try saving in a different format. I don't see where your paths are any sort of problem nor that making a raised bed would be very hard at all. However you might consider an air lock type of setup so just incase your stove smokes back you aren't killing to many plants. Exhaust up like a chimney, fry chickens on stove, Bon appetite. you have several options but as erica said running the duct in a bid of wood as your walls for the raised bed works well (personally i like my cob beds because it allows me to make more soil over time). put a slight upward slope in the ducting layout (about 1/4" over 10") and i like to bring the vertical back to the barrel and then up so i cant use a bit of the heat to ensure my draft. you will need to spend a bit of time seeing how much a wet bed varies compared to a dry bed.
ok hope this helped
11 years ago

Matthew Nistico wrote:

1. Since the intake duct will be mated with a more-or-less firm seal to the oustide air kit on my woodstove, then the total length of this duct is added to the total drag on the airflow through the system. Even though my conventional woodstove will likely produce more than enough draw to overcome the added drag - since afterall my woodstove will be blasting 400+ degree exhaust up the chimney - more drag is still more drag; it is still a drain on the efficiency of the system. So why use a "corrugated" dryer vent when I could use a much lower-drag smooth rigid metal duct instead? In the future, when and if I mate this system to my RMH, this should prove even more critical, right?

2. Along those same lines, I understand the importance in RMH design to maintain a consistent cross sectional area at every stage of the air channel through the heater, from beginning to end. As I understand the physics, this is to ensure consistent air flow. Otherwise, the air flow capacity of the entire system would be effectively reduced to the capacity of the single narrowest bottleneck anywhere along its lenght, right? Surely the same logic applies to air flow through my woodstove system (right?). So if that is the case, why attach a 4" intake air duct to a woodstove with a 6" exhaust pipe? And again, even if the woodstove has the draw to power through this restriction, wouldn't this become even more of an issue when attaching to the RMH in the future?

Thoughts, reactions, criticisms, suggestions...?


the little 4 inch intake cant provide the amount of air your fire needs to burn clean in a 6 or 8 inch RMH. it does not need to be smooth for an intake but it does need to be large enough.

Ok we will go into this a little because its important. yes the constant CSA is important in a box stove; surprise!!! your stove has more air intakes than you know many are hidden from you or inaccessible so you cannot block them off. the other thing is that you cannot get your box stove up to clean burning temp without voiding your warranty. the Temp for a good clean burn is 1200 and up. this would make your stove glow really nicely and very quickly void the warranty. So the reality is your stove is starved for air in the first place but now days stoves have more holes in them so you cannot totally shut the stove down to a smolder (Air quality). What most have these days is a catalytic converter to scrub the particles and some of the other nasties out of the exhaust.

another consideration as i said in the above post why would you want to breath stale air?

any how hope this clears a bit up.
11 years ago
why do you want to breath the crappy air yourself?

Its not a trouble to heat the room and your house has to cycle air at a certain rate in any case to allow you to not get sick from all of the off gassing crap and your own breath. I don't think you want to breath all the stagnant crap but most folks soon figure out that a nice clean breath of air is a good thing.
11 years ago
hey guys and gals. kitty litter is not a good choice and nor is any bentonite clay unless you have very carefully worked with it before. its absorption of water is huge and you have to know how to deal with the huge shrinkage as it dries. use an earthen mortar rather than lime because lime and cement burn out. sand and clay do not.

alternatives are brick, stone, and such, cement is not a good idea as it tends to burn out. there are lots of ways to make an RMH look good, including A nice plaster job. if you are thinking the cob cannot take the abuse then build the mass and ducting under your work benches (often this is not used for any real need.)
or if you are short duct it under your floor so you get the benefit of the heat and the cushion of the cob, build it next to the wall and make it look like a wall, Or since it is a work shop and has wood scrap you would do better with a simple pocket rocket that will burn up you waste wood and heat the place.
if you just use the stove when you use the shop you probably want the quick heat option.
hope this helped
11 years ago
time temp and turbulence
you want the turbulence its good for the burn. mixes the air gas makes a nice clean fire.

why are you trying to make a steel stove? its not as easy as stacking bricks and you cant really reuse the materials after you cut them up.
I just dont understand the insistence that metal is somehow better than masonry. each does a job well, its not so good to try and make them do the others job.
11 years ago