rocket stove exhaust: water, carbon dioxide, and what else?

I've seen it repeated many times that a properly designed and operated rocket stove exhausts only water vapor and carbon dioxide.  I'm having a difficult time believing that, though I would be happy to be convinced.

wood is made mostly of carbon and hydrogen and a little oxygen, but that's not all it's made of.  there are other elements in there as well.  some of those, such as calcium and potassium, mostly remain in the stove as ash.  I'm not familiar enough with rocket stoves to know what temperatures are involved in the combustion chamber, but it wouldn't surprise me if K, S, B, Cu, and Zn could all make up small portions of the exhaust.  if it's truly hot in there, in the vicinity of 1000 ºC or more, there could be nitrogen oxides created.  I'm quite sure that all of these things would make up a very small portion of the exhaust, but a portion no less.

I'm not trying to cast doubt on the environmental pedigree of rocket stoves; I'm a big fan rocket stoves.  I do believe that we shouldn't be claiming things that could give opponents of rocket stoves an opportunity to undermine our credibility.

so, am I way out of line?  ignorant?  picking nits?

Per your request,

Wood Smoke Emissions
Burning Issues/Clean Air Revival, Inc.
Draft: Wednesday, June 6, 2001
1
Pollutant Physical
State
Emissions for
g/kg Wood
Carbon Monoxide V 80-370
Methane V 14-25
VOCs (C2-C7) V 7-27
Aldehydes V 0.6 -5.4
Formaldehyde V 0.1- 0.7
Acrolein V 0.02- 0.1
Propionaldehyde V 0.1- 0.3
Butryaldehyde V 0.01-1.7
Acetaldehyde V 0.03 - 0.6
Furfural V 0.2-1.6 1.6
Substituted Furans V 0.15 -1.7
Benzene V 0.6-4.0
Alkyl Benzenes V 1-6
Toluene V 0.15 -1.0
Acetic Acid V 1.8 -2.4
Formic Acid V 0.06-0.08
Nitrogen Oxides (NO,NO2) V 0.2-0.9
Sulfur Dioxide V 0.16-0.24
Methyl chloride V 0.01-0.04
Napthalene V 0.24-1.6
Substituted Napthalenes V/P 0.3-2.1
Oxygenated Monoaromatics V/P 1 - 7
Guaiacol (and derivatives) V/P 0.4-1.6
Phenol (and derivatives) V/P 0.2-0.8
Syringol (and derivatives) V/P 0.7-2.7
Catechol (and derivatives V/P 0.2-0.8
Total Particle Mass P 7-30
Particulate Organic Carbon P 2-20
Oxygenated PAHs V/P 0.15-1
PAHs V/P
Fluorene V/P 4x10-5 - 1.7x10-2
Phenanthrene V/P 2x10-5 - 3.4x10-2
Anthracene V/P 5x10-5 - 2.1x10-5
Methylanthracenes V/P 7xl0-5 - 8x10-5
Fluoranthene V/P 7xl0-4- 4.2xl0-2
Pyrene V/P 8x10-4 - 3.1x10-2
Benzo(a)anthracene V/P 4x10-4 - 2x10-3
Chrysene V/P 5x10-4x10-2
Benzofluoranthenes V/P 6x10-4- 5x10-3
Benzo(e)pyrene V/P 2x10-4 - 4x10-3
Benzo(a)pyrene V/P 3x10-4- 5x10-3
Perylene V/P 5x10-5 - 3x10-3
Ideno(1,2,3-cd)pyrene V/P 2xl0-4- 1.3x10-2
Benz(ghi)perylene V/P 3x10-5- 1.lx10-2
Coronene V/P 8x10-4- 3x10-3
Dibenzo(a,h)pyrene V/P 3x104- lx10-3
Retene V/P 7x10-3 - 3x10-2
Dibenzo(a,h)
anthracene
V/P 2x10-5 - 2xl0-3
Trace Elements
Strontium P 3x10-3 - 1.8xl0-2
Magnesium P 2x10-4 - 3x10-3
Aluminum P 1x10-4 - 2.4x10-2
Silicon P 3x10-4 -3.1x10-2
Sulphur P 1x10-3 - 2.9x10-2
Chlorine P 7x10-4 - 2.1xl0-1
Potassium P 3x10-3 - 8.6x10-2
Calcium P 9x10-4 -1.8x10-2
Titanium P 4x10-5 - 3x10-3
Vanadium P 2x10-5 - 4x10-3
Chromium P 2xl0-5 - 3x10-3
Manganese P 7x10-5 4x10-3
Iron P 3xl0-6 - 5x10-3
Nickle P 1x10-6 - 1x10-3
Copper P 2xl0-4 - 9x10-4
Zinc P 7x10-4 - 8x10-3
Bromine P 7x10-5 - 9x10-4
Lead 1x10-4 - 3x10-3
Particulate Elemental Carbon P 0.3 - 5
Normal alkanes P 1x10-3 - 6x10-3
Cyclic di-and
triterpenoids
P
Dehydroabietic acid P 0.01 - 0.05
Lupenone P 2x10-3 - 8x10-3
Friedelin P 4x10-6 - 2x10-5
Chlorinated Dioxins P 7x10-3 - 7x10-2
Particulate Acidity P 7x10-3 - 7x10-2
Additional wood smoke
emissions found in other
studies
Cresol33 P
Isopimaric acid3 P
Ethylbenzene3 V
Arsenic4 P
Cesium9 P
Cadmium4 P
Molybdenum5 P
Selenium5 P
Carbozole2 P
Acridinee2
Barium
Phosphorus P
Sodium7 P
Phenathrol2
Phenathrene2 V
d10-phenanthrene2 V
Acenapthylene2 V
Nitronaphthalene2 V
d12-chrysene2 V
3-methylcholanthrene2 V
Acenapthene2 V
Indeno (1,2,3,c,d,) pyrene2 V
Molds in wood ash13
Thermoactinomyces
vulgaris 13
S (0.1%),
Penicillium sp mixture 13 S (1/10 wt/vol).
Aspergillus fumigatus13 S (0.1%),
Cladosporium herbarium13 S (1/20 wt/vol),
Micropolyspora faeni13 S (1/50 wt/vol),
Alternaria tenius13 S (1/10 wt/vol),
All pollutants and emission weights taken from A Summary of the Emissions Characterization
and Noncancer Respiratory Effects of Wood Smoke, Timothy V. Larson & Jane Q.Koenig, From
Table 2, EPA-453/R-93-036, 46p. (US EPA December 1993).
Molds based on isolates from wood ash cultures: Greer Laboratories, Lenoir, NC.

how many of those would be reduced by relatively high temperatures inside a stove and relatively complete combustion?  I would guess that the trace elements won't be affected, but what about some of the more complicated or nasty compounds?

This is easier to read
http://burningissues.org/pdfs/WSComparisontable%209%2001%20.pdf

this is the homepage:

http://burningissues.org/car-www/index.html
this site goes into depth on woodsmoke as a line item, but obviously doesnt adress upstream cost of burining gas (which it claims is 16,000x as clean. Id wager that this is some sort of black math, as it doesnt count the carbon footprint of mining, shipping and industrial infrastructure to get the gas from the ground to the home.

Nor is it likely to consider the ecological benefits of carbon sequestration as provided for by woodlot maintenance.

here it is anyhow.
http://www.burningissues.org/home-heating.htm

to the question:

tel jetson wrote:
how many of those would be reduced by relatively high temperatures inside a stove and relatively complete combustion?  I would guess that the trace elements won't be affected, but what about some of the more complicated or nasty compounds?

I would expect all VOC's and complex organic matter (fungus, bacteria, etc. maybe some sproulate could make it out, and be viabl;e. the stuff can go through outer space, man...) but the most of it will combust in the burn chamber- they are Volatile and that is what volatile gasses to, organizms  are carbon based a and carbon will oxidize at that temp, and gladly give up its H to do it.  These things vaporize or combust and when mixed with oxygen- they oxidize. most of these and the heavy particulate- including traces of strontium- will settle on the horizontal exhausts floor in the clean out.

well, lets take a worst case scnario look at strontium. Strontium levels in woodash gathered from burn samples across new england show levels about 100x EPA toxic disposal minimum.

http://ratical.org/radiation/inetSeries/woodash.txt
(anyone wanna snopes that doggy for me?

so there can be nasty stuff in woodash. that strontium aint going out the flue.

and it doesnt matter what kind of stove you used, its still there.

bot the VOC's,id wager anything that combusts at 900f is broken into simple molecules - and its either float (gas) or sink(solids). if its not burning at that temp, its precipitating into ash. only the stuff that can drain or float at just a hair over STP will make it out. C02, vH20, maybe some random H and O2. it'd have to be lighter than air to make it oput is all im saying. lighter than air.

everything else fractionally precipitates. thats the joy of a 40-80 foot long fractional gradient with a small negative pressure generator pushing the combustion to the exhaust port. Laminar flow of these gasses, co-efficient with with thermal mass BTU uptake andits  max cap, fills the mass volume like rilling water fills a swale. minimal turbulence and decreasing temps along the exhaust tunnel leads to relatively complete precipitation of particulates.

yes, theres shitloads of nasty in the woodsmoke. and most of it is catalytically converted, and falls as precipitate in ash, and composes less than .5% of the volume and weight of the original wood. and its full of nasty. 100x the concentraion of strontium as the EPA allows without toxic disposal requirements.

and that happens in much less efficient conventional and pellet stoves as well.

tel jetson wrote:
how many of those would be reduced by relatively high temperatures inside a stove and relatively complete combustion?  I would guess that the trace elements won't be affected, but what about some of the more complicated or nasty compounds?

As I indicated to you via pm, the few milligrams of lead ain't going away, pretty much none of the metals will and wile folks might be prone to think they remain in the ash, they do not and even a product as dense as lead indeed become airborne and airborne lead is an EPA listed hazardous pollutant that exist in the smoke from wood burning. I have no interest in arguing this or providing the math and explanations of fluid dynamics to try and prove this to the non-believer and I would not do so in the manner prescribed by this web space which would just be disruptive and unpleasant for those involved.

Deston Lee wrote:

and it doesnt matter what kind of stove you used, its still there.

Very very true, and unless I am mistaken, at much higher levels than in the typical RMH design as it has some very significant differences that will indeed reduce them or better said contain more of them.

regarding lead

lead has been studied as a combustive product for ages- in fact it was studies from the 60's and 70;s on lead concentration along roads that led reduced and unleaded gasolines.

the location of the hard science is not known to me anymore, but memors says that the lead concentrations were highest with 12 feet of any 2 lane given road way with 500-100 vehicles daily. an normal suburb collector.

outside of 30 ft from roadway, lead levels returned to normal for the region.

along major arterials lead levels may be elevated in soils up to 180ft from the road.

now cosider: the busier the road the faster the cars, the more turbulence in the air.

the lead particluate comes out under pressure. explosive pressure from an internal combustion engine. it litterally explodes from the exhuast at several times atmospheric  pressure into a maelstrom windbeating automobiles.

OTOH, the exhaust coming from a RMH is barely more than one atmosphere in pressure, and is flowing rather than exploding.

whats gonna keep the lead aloft>it only traveled 30 feet away from a road that gets 1000 cars a day. at STP with barely a nudge, the particulate is gonna sink. plunk. somewhere in the fractional gradient of a 80ft long settling exhaust tube/heat exhanger.

wear a dust mask when you sweep your clean out ports!

Deston Lee wrote:

wear a dust mask when you sweep your clean out ports!

And don't let your cats in the room while you're doing it, either.  Can't imagine anything worse than having spent the afternoon cleaning out the stove, then having spent the evening sweeping and vacuuming all the stuff that managed to get all over the floor, then sitting back and finally relaxing, only to have your kid come in and ask, "Have you seen Fluffy?  I can't find her, and I haven't seen her all afternoon."

(Actually, I CAN imagine something worse: the above scenario followed where you get the flashlight and spend 45 minutes taking off the ports and looking inside the tubes, stopping only when your kid comes back in the room to say that she found Fluffy; Fluffy had been taking a nap in one of your dresser drawers when the drawer got closed; and finding out the next day that the cat in fact HAD walked through the ash before getting in with your formerly clean clothes.)

I suppose that we can start with the idea that if somebody is heating their home with 1/8 of the wood (I am trying to break the habit of saying 8 times less - which makes perfect sense to me - take what you have and divide by , then it is fair to say that there is probably 1/8 of most pollutants such as lead.

Now, the next step is that both RMH and conventional start off with smoke to get the system heated up.  But the RMH always rushes to a hottest possible burn.  Further, during the burn, the RMH remains at the hottest possible while the conventional depends on the operator.

Conventional gets creosote and RMH, anecdotally, does not.  This, I think, is a powerful indicator of how much cleaner the RMH is. 

It would be great to be able to get some hard numbers on a few of the more well known pollutants such as CO.  Does a RMH put out less than 1% of the CO that a conventional wood stove puts out?  Does a RMH put out less CO than a candle?

Hit control minus (-) 10 times and you will see 10 times less from here.  Well maybe it won't recede that far.?

To calculate the difference in producing wood, cutting, moving, storing, moving wood again, (to the burn area): To burn 1/10th wood compared to burning 10x more wood... To realize that the wood supply around me dwindles at the rate of .5 cords a year compared to 5 cords a year...This boggles my mind with thoughts of the person who cuts the .5 cords per year could use hand tools and the 5 cord person most likely wouldn't. (It can be done, but remember your time and effort are involved.)

So if .5 RMH person and 5.0 conventional wood stove person, both use chainsaws, then .5 person is going to use 1/10th number of chainsaw blades 1/10th sharpening the blades... 1/10th gasoline , 1/10th bar oil (do I need to regress to how much is involved in getting the gasoline and oil to the chainsaw). 5.0 is going to require 10X more chainsaws in his lifetime (chain saws require energy to manufacture and cost 5.0 $$$ to buy them).

The 5.0 cord person is going to have to go farther from the cabin each year as the trees nearby are used 10x faster.   1/10th person is keeping 10x more trees to scrub the air of co2. (Not to mention that 1/10th might be using just scrap dead wood.)

Calculating the environmental effects of using the RMH compared to a conventional wood stove, is not a simple undertaking.
The savings go far beyond simple what's -in -the -exhaust calculations.

ronie wrote:
Calculating the environmental effects of using the RMH compared to a conventional wood stove, is not a simple undertaking.
The savings go far beyond simple what's -in -the -exhaust calculations.

I agree completely.  I'm just concerned that when folks make claims about these stoves that turn out to not be true, detractors will jump on those claims and folks who might have been on the fence about them could be scared away.  if this one widespread claim (water and CO[sub]2[/sub]) turns out to be false, the credibility of all the other very real advantages of rocket mass heaters will likely be questioned.

I think the actual and substantiated advantages are impressive enough that hyperbole is not necessary and is in fact detrimental.

I really believed that the gaseous exhaust of wood combustion is CO2 and moisture vapor... I never knew that there was any thing else in the gaseous exhaust.. So i would be interested in what winds up in the ash and what winds up in the atmosphere.

Everything i read, is just the same as Erica said, that the products of wood combustion is CO2 and moisture vapor.  This thread was the first that i heard of all that is in the wood... I imagine that, if the wood has all that in it to start with, then it will return to the environment whether the wood is burned or if the wood decays.

If we get near complete combustion, it might be easier on the environment than natural decay..

ronie wrote:
This boggles my mind with thoughts of the person who cuts the .5 cords per year could use hand tools and the 5 cord person most likely wouldn't. (It can be done, but remember your time and effort are involved.)

In a mass heater, large logs are not needed to extend burn time. So rather than a saw, a lopper could be used to cut small diam stuff... no splitting needed. Pruning can happen at the same time. Drying (seasoning) is faster too. I was thinking a capped 6 inch vent pipe about 3 feet long could be made into a fuel cartridge. drop it into the feed tube and the cap will keep it from acting as a chimney. There might need to be holes at the feed tube level for more air if the corners are not big enough. The the wood can be cut longer than 18in. and the fire need less tending. (though not less monitoring)

tel jetson wrote:
I agree completely.  I'm just concerned that when folks make claims about these stoves that turn out to not be true, detractors will jump on those claims and folks who might have been on the fence about them could be scared away.  if this one widespread claim (water and CO[sub]2[/sub]) turns out to be false, the credibility of all the other very real advantages of rocket mass heaters will likely be questioned.

I think the actual and substantiated advantages are impressive enough that hyperbole is not necessary and is in fact detrimental.

Good points there Tel. I do want everyone to look into the RMH because it is a great improvement in heating technology. (And not be put off because we over state the end product.)

Len wrote:
In a mass heater, large logs are not needed to extend burn time. So rather than a saw, a lopper could be used to cut small diam stuff... no splitting needed. Pruning can happen at the same time. Drying (seasoning) is faster too. I was thinking a capped 6 inch vent pipe about 3 feet long could be made into a fuel cartridge. drop it into the feed tube and the cap will keep it from acting as a chimney. There might need to be holes at the feed tube level for more air if the corners are not big enough. The the wood can be cut longer than 18in. and the fire need less tending. (though not less monitoring)

Len that fuel cell might work - It would add costs to the operation, but then the whole thing is not a lot of money spent for the amount of work it saves. I would be interested to know if you try the fuel cell.

Yeah i bought the best lopper that Lowes had in 2007 and I can stay way ahead of my rocket cooker or rocket heater.

ronie wrote:
Len that fuel cell might work - It would add costs to the operation, but then the whole thing is not a lot of money spent for the amount of work it saves. I would be interested to know if you try the fuel cell.

It will be a while, my Yf is doing full time studies (nursing), so I am doing single parenting pretty much for a while, not much time for projects. I have to build the RMH first.

Yeah i bought the best lopper that Lowes had in 2007 and I can stay way ahead of my rocket cooker or rocket heater.

About what I figured. I think that is the whole point of the RMH.... or any high mass heater. It is not about being more efficient that an iron box. It is about making a heater that can run comfortably at the cleanest burn. As has been said, a good iron box can be run with a high efficiency, but it will make the room to hot, so it is run at a smolder all the time. A mass heater is run as hot and hard as it can be, but the mass keeps the room from over heating. The Mass heater is run for only a few hours in a day and the mass heats the rest of the day. So even assuming that the mass heater and the iron box run at the same efficiency, the one that only runs part time will use less fuel and pollute less than the one that runs full time. Anything that burns a fuel will create pollution. Burning less fuel will create less..... heating a smaller space will make for cleaner air too, as will insulation and high (thermal) mass housing.

While it is true that a lower temp surface on the mass heater will transfer heat slower than a hotter iron surface, the lower temp surface will not scorch the dust in the air. Even these baseboard heaters seem cool enough not to burn the air, I breath better than I did with forced air heating in the last house.

I would like to see a really small mass heater (small burn chamber) that could fit in the average bed room and just burn a few twigs.... maybe with a phase change box for mass... some thing that can keep a room from 80 to 150 sqft at about 66 to 68F for 8 to 10 hours... burn for an hour or so to heat the mass. I try to only heat the rooms I need now with hydro, why not with wood too?

Len wrote:
While it is true that a lower temp surface on the mass heater will transfer heat slower than a hotter iron surface, the lower temp surface will not scorch the dust in the air. Even these baseboard heaters seem cool enough not to burn the air, I breath better than I did with forced air heating in the last house.

This is not uncommon at all. Forced air units are air hogs and will be bringing in about 40-50 cubic foot of outside air per cubic foot of gas burned and a typical forced air furnace uses about 10 cubic foot of gas per running hour that is a lot of cold dry air which by itself would cause breathing issues for some folks.

By burning less, you are bringing less in so you kind of have a win win, less pollution from the burnt dust and less outside dry air entering the space.

The purpose of this video is to give folks an idea of how clean the
exhaust is while running a rocket mass heater in Missoula, Montana.

When we first start it, there will be smoke.  And there was smoke in
the middle of the burn sometimes, but I think that most of that has to
do with things that need more design improvements.  For most of the
time, the exhaust was a lot like what is shown in the video - there is
fire, but no smoke.  Marci Anderson gets her nose right in there.

Another important thing to note is that the temperature of the
exhaust:  see how we have a hot, clean fire burning and guido does not
burn his hand when he puts it in the exhaust.  It feels warm, but not
hot.  We measured it at about 90 degrees when the barrel was at about
850 degrees.

I show the materials being moved by the freecycles folks from the
freecycles HQ in Missoula to Caras Park (downtown Missoula).  Then a
bit of building it.

This rocket mass heater is a prototype for some variations.  A wood
box shows a different aesthetic, a much taller heat riser design,
using dry, loose fill (rocks and sand).  This should be a lighter
design than other rocket mass heaters - so it might be good for places
that have a wood floor.

This might also be the fastest time a rocket mass heater was ever
built:  an hour and fifteen minutes.

paul wheaton wrote:
For most of the time, the exhaust was a lot like what is shown in the video - there is
fire, but no smoke.  Marci Anderson gets her nose right in there.

along the theme of this thread, just because it doesn't smell like smoke and isn't too hot doesn't mean it's a good idea to stick one's face into it.  though it appears relatively complete combustion was achieved, there are likely still some toxic substances in the exhaust.

looks like a fun project otherwise.  good work.

I agree with Tel Jetson. I'm completely convinced that rocket mass heaters are the way forward and Ill probably not ever try to heat a house in a different way again. But Carbon Monoxide is a really dangerous, unnoticed and silent killer that all combustion produces and I would love to see more research and awareness on it's presence or possible presence when building rocket mass heaters. Just stating that burning less wood will cause less dangerous gasses is not enough because even a small amount in the house is damaging. It would be nice if somewhere in the future there is enough substantial evidence that proves that rmh's are not only environment and money savers but also much more safe...has anybody yet put a carbon monoxide detector close to the exhaust?

I think if you want to make it even better everybody should be advised to take safety into consideration and to put a carbon monoxide monitor inside, close to the heater and one outside close to the exhaust, if that doesn't reach above all windows.
And that might be a bit of an expense but when everybody is starting to build their own that could safe lives.

Newbie wondering if anybody ever bothered to ask Chemistry Dept at UM campus in Missoula to see if any seniors would be interested in firing up GC/MS and other fun analytic tools and methods to collect and analyze actual samples from Paul's RMH?  Maybe its just the chemist in me, but it'd be nice (and easy) to actually KNOW what exactly is coming out the stack and what's the composition of what little ash remains in system.  Y'all have an embarrassment of riches when it comes to potential collaborators on this kind of little research project.  UM lists the following research centers (in addition to just Chem Dept in general) who might have someone with some interest in following this up:  Center for Biomolecular Structure and Dynamics; Center for Environmental Health Sciences; Center for Integrated Research on the Environment (CIRE); Center for Natural Resources & Environmental Policy; Bolle Center for People and Forests; Montana Biotechnology Center; and the Montana Institute on Ecosystems (IoE).  I'm pretty sure there's someone at UM looking for a small little research project, like a senior project for BS in Chem.  Characterization of particulates released would be of special interest, I'd think.  It'd be nice to be able to point to actual analysis results, rather than arguing only from supposition.  As I have not yet found such analysis results for RMH being reported, I assume that either it hasn't been done or that my Google-search-engine skills are failing.

Peter van den Berg in the Netherlands has done considerable RMH research and testing with a professional Testo 330/2 gas analyzer. This does not get into particulate or ash analysis, but it does show CO and CO2 levels in the exhaust, among other things, and the best designs give very low CO levels during the body of a combustion run, with spikes at start and end.
https://permies.com/t/72398/Peter-van-den-Berg-graph
https://permies.com/t/40/55532/Batch-rocket-resource

I'm sure some government researcher has done analysis on woodstove emissions; the fact that RMHs burn so much hotter than ordinary woodstoves would indicate that noxious chemicals that might be emitted are burned up. I have seen lists of incomplete wood combustion byproducts and their combustion temperatures, and nearly all would be burned up in RMH core temps. The very hottest experimental RMHs may be able to reach temperatures above 2300F, which would burn nitrogen to create NOx compounds, so practical versions would want to avoid such extreme temperatures. The ideal operating range would be 1800-2000F which burns pretty much all noxious compounds while not creating new ones.

Glenn, that flue gas analyzer only has three distinct sensors for three substances.  That's good, in general, for testing for dangerous situations, but for really making the case for benefits of RMH, a more in-depth analysis of what ALL the stuff there in the sample going up the stovepipe (or left behind in the ash pit) just can't be beat.  I suspect y'all will be happy you tried this.  A GC/MS (Gas Chromatograph/Mass Spectrometer) will give a detailed analysis of essentially ALL the substances (molecules) in the sample, it's shown as a graph plotting molecular weight against amount of the substance detected, so it shows a ragged line with a bunch of "peaks" for each and every molecular weight in the range selected for analysis.  The peak tells the chemist how much of the substance(s) of that molecular weight were present in the sample.  It gives a whole lot more info about exactly what's in the sample.  

This is the perfect size project for an undergraduate student to run as part of a practical advanced analytic chemistry lab (usually an independent study or senior  project that runs for an academic quarter or semester) under faculty supervision.  Seriously, my old profs would have thanked you for bringing this kind of practical problem to them.  Only costs the owner of the RMH a little time and attention when the Prof and student(s) come to get info on the problem and to collect samples (ash, flue gases, and maybe some of the wood going in).  Good chance to give 'em a very short earbug about permaculture and why RMH matters vs. traditional combustion heating systems.  Prof may have some other (better?) tests on which I'm not up-to-date.    (My chem ed was just a BS and many decades ago, so I'm just going on memory of actually running the instruments of that time in school labs and at work in hospital laboratory.  I switched to a WHOLE 'nother line of work shortly after completing that degree.  Long story.....)           -jimh.