Erica Wisner

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since Feb 10, 2009
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Was born, raised, and turned loose on an unsuspecting world.  Originally an educator, now growing into writing & publishing, fire fighting, family care teams, and mountain ecological maintenance.  Prone to extended explanations.  (I like to explain things so that a 5-year-old and her PhD grandparent can both enjoy and 'get it'... no offence meant if you're somewhere in between!)
Okanogan Highlands, Washington
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Recent posts by Erica Wisner

It's cold enough:
We are defrosting our freezer in winter, by setting all the frozen contents outside where they will stay frozen (in coolers for wildlife protection)
and putting hot pans/kettles of water inside the empty freezer to heat it up.

we had a little break where it got warm enough for icicles to drip, and that's when we scrambled to make sure the coolers were full enough that things would not soften.
Now it's back to powder and rock-hard outdoor food cache.

I am trying to go for several miles in the snow for exercise, but my lungs feel pretty weird when I come back in.  Not sure if I'm cleaning them out or scarring them up. 

It's so cold we caught the tenderfoot dog trying to stand on 2 legs to get 2 feet off the snow at once.  Haven't caught him on 1 leg yet.

1 week ago
I was thinking along the same lines as Larry, but maybe using larger irrigation pipe (you can get 2" diameter with some flexibility, reasonably priced), so you can flush your greywater directly away and not store/handle it.
The same laws that condemn urine (which IS almost always considered "black water" and sewage), and what comes out of the sink, tend to be very prohibitive about unlicensed "handling" of sewage.  So if you can plumb the trailer to the sewer line, instead of handling a honey cart, you'll probably be in even better shape for legal concerns.

For handling, I do like the idea of using what the RVers and boat folks have already tested and proved out.  This is not a new problem, just new to you.

Leaving aside the question of whether killing everything in your sewage is a good idea (i don't think it is, for so many reasons...),

I don't think chemicals will completely do away with the smell. 
Ammonia from rotting urine is the strongest odor, and it will still be present even after strong chemicals kill the bacteria.  So will fat-bound odors like putrescine and BO, for the most part.
Not all bacteria is bad (far from it), and not all sterilized water smells good. 
It usually smells like the chemicals (chlorine, iodine), plus any "deodorizers"/perfumes, plus a good part of whatever it smelled like before. 
It is still somewhat toxic too, it just won't give you typhoid, cholera, giardia, or other forms of dysentery.

Boiling or UV-sterilization are the least-toxic ways to treat potable water, and there is not much point to boiling sewage... not only would it stink, but the nutrient content would attract airborne bacteria, and things would be back in action within hours.
UV-sterilization is sometimes used as the final stage for very clear water, but would not work reliably on cloudy/chunky/nutrient-dense material (light just breeds algae in those conditions).

With chunky grey water with food particles, possible grease, and very high nutrient content, I suspect you'd have a hard time totally rinsing down the sides to the point where your material would be disease-free, let alone odor-free. 

I'd definitely go for more frequent emptying, or an instant-empty drain pipe (maybe equipped with a gluck-tolerant bilge pump or what Larry recommended, if it's an uphill run to the nearest sewer access).

The idea of using grey water to water plants, etc. is still workable.
You don't have to let it go down the drain first. 

I have a greywater sink, but sometimes collect water in a bucket at my feet to take to other parts of the garden on the other side of the house.

There is no law against rinsing your dishes into a dishwater pan instead of down the drain, as far as I know. 
There is no law against brushing your teeth and spitting outside... at least I don't think there is.... nor about how to dispose of "spitoon" contents if you do happen to live where public spitting has been outlawed.
There is no law against rinsing a dish into a potted plant, or peeing on one for that matter, as far as I know.  (I don't recommend peeing directly on indoor plants, however, unless they are getting a LOT of water in fairly short order... most places recommend 10:1 or 20:1 water to urine for plant fertilizer.)
I sometimes make "fertilizer" for my houseplants, up to a few times a year. I won't go into further details, but it seems to work.

If you do end up using the tank-and-tote method as you first outlined, I personally would favor getting a fairly small tank, so you have to empty it more frequently, and its easier to transport/get rid of if you end up moving to a different landlords' place some time.  Then play games with yourself (within the bounds of reason and your agreements) to see how little water you can allow down the drain.  If you are using a lot of water you'd empty it daily/every other day.  If you get creative about minimizing water use, and re-using mostly-clean water in appropriate ways, you might be back down to emptying once a week, but a lot smaller job.

Final note: As far as I know, all sewer connections and septic system connections are supposed to have vents / "stand-pipes," because the decomposition of household waste in sewage can cause gas bubbles. 
You don't want the plumbing to build up back pressure into the house. 
For the same reason, I'd recommend against trying to make the tank 100% airtight. 
Vent it above your roof, or at least outside your space, or it will vent itself up your drains (and I imagine that's exactly where you DON'T want the smell).  Make sure that the vent is big enough that liquids "burp" into it, rather than rising up it. 
Sometimes boat and RV toilets have a close-off or check valve, as an added preventer against odors and back-flow.

Lot of water has gone under this bridge already... so to speak.  good luck with finding a solution that makes you, and your landlord, happy and satisfied.
2 months ago
Update on this topic:
- We have seen evidence of creosote in 2 rocket mass heaters now.
One has definitely had at least one chimney fire, and possibly more than one.

Both of the stoves involved had some big, glaring problems as far as proportions, and did not meet the guidelines now published in our Builders Guide book.

In one case, the heater had relatively normal proportions except it had 14 elbows in the pipe between firebox and chimney.  This is roughly double what we would normally recommend, and it causes the exhaust to slow down a lot.  This stove is difficult to light, and touchy to operate. 

In the other case, the heater was built using tricks from at least 3 different builders, in a workshop led by someone who subsequently stopped returning calls from the owner.  
Combining tricks from different stove designs, without testing and follow-up, often results in a Frankenstein's monster with functional problems. 
In this case, one trick (not recommended) involved forming the heat riser around wire mesh interior formwork.  When this burned out, the inner lining of the heat riser crumbled away, leaving it much larger than it should have been.  Combined with a too-short feed and some other dimensional errors, this led to the fire burning with a bad fuel-to-air ratio, and to over-powered draft that probably helped draw sparks all the way to the exit chimney to light off the resulting creosote.

- We recommend sticking with proven proportions, and proven combinations of features, wherever possible.  for some reason, a LOT of builders want to re-design the rocket mass heater on paper without much (or any) practice..
- We recommend building a proper chimney, with proper clearances to combustibles, and proper structural installation (three to four screws per joint, through-ceiling and through-roof collars that support the weight of the pipes, etc).  Modern manufactured chimneys, when installed correctly, will protect the surrounding structure in the event of a chimney fire.
- We recommend inspecting any stove or fireplace or working chimney at least once per year, regardless of the length of your heating season.  (Folks in warm climates don't get to stretch it out, because a seldom-used chimney is even more likely to have problems than a routinely-used one.  Folks in very cold climates are welcome to inspect more often if they see fit.)  Remember that DIY chimney maintenance came into fashion within living memory for most of the folks who raised us; get a professional chimney sweep if you can.
- If you find creosote (sticky or crumbly black material) in any masonry heater or rocket mass heater, or its chimney, there is a problem. 
It could be poor design, air leaks/poor construction, poor fuel, or operator error (such as shutting down the fire before the fuel is finished burning).  The problem should be diagnosed and fixed, and the creosote removed, before continuing to use the heater.

2 months ago
Does your heat come with a chimney?
If you heat with wood, coal, straw, dung, or propane, the exhaust has to go somewhere.
Some folks may not realize just how critical a good chimney is to the whole operation.
Off-grid living (and that stove you keep for snow days and emergencies, for that matter) come with chimney installation, maintenance, troubleshooting, and operational safety basics to learn.

I've learned a lot about the history of fire prevention (often learned from specific catastrophic fires, and from "great new ideas" that led to a wave of fires and then a regulation to prevent future ones). 
Some of that's as a heating geek, and more recently I've seen the flip side as a volunteer fire fighter in a tiny rural community. Only a few hundred year-round residents live in our district, yet we've had 3 or 4 chimney fires in the past few years. 
1% per year seems like a really high number for a preventable problem like chimney fires.  And the more I look around, the more it seems like we all think we know how chimneys work, and we really mostly don't.

Chimney fires suck.

One of our worst fires, last winter, happened to a couple who had just cleaned their chimney. 
Possibly some of the creosote got dislodged and settled down at the bottom closer to the heat, possibly some part of the chimney got bumped and ended up with inadequate clearance to the wall or ceiling combustibles.  Possibly the through-wall cleanout access wasn't securely installed, and cleaning opened a gap.  It was impossible to tell after the fire.

Both occupants were on site when it happened, and were lucky in that they had time to move some belongings out of the farthest rooms of the house.   The room with the stove in it already had fire rolling across the ceiling, and the whole structure was a total loss.
He was trying to laugh it off with black humor, she was still shaking from hearing the cat screaming in the attic before it died.

We did what we could, with volunteers from the two closest fire districts, but it wasn't much.  We helped protect some nearby structures, gave them phone numbers to call for emergency housing help.
We had to finish the job with shovels and buckets of ice, as it was -10 F and the fire trucks were freezing faster than they could pump water.

That incident really stuck in my mind. 

Sometimes when I mention chimney fires, folks tell me, "oh yeah, we used to have a chimney fire 2 or 3 times a year, the chimney would be red-hot and my dad would be up on the roof yelling at us to close the stove, if you opened it it would go "boosh" and singe your eyebrows off." 


I twitch now when someone tells me "I built my own chimney even better - I used well casing instead of stovepipe" or some other DIY "improvement" that, for a whole host of reasons, is likely to cause a major fire hazard.

Visible smoke, and mid-winter chimney cleaning, both seem to me now to be early warning signs of a possible, catastrophic, chimney fire. 
Creosote in any form is an early warning sign of a preventable emergency. 

A past chimney fire is not just a warning sign or a close call - it's a preventable emergency that you survived.
Modern, manufactured chimney components are designed to take ONE chimney fire without failure, meaning you might not lose your house just because you had a chimney fire.
Repeated chimney fires can weaken the parts, loosen the joints, and degrade critical insulation and precise (scanty) safety clearances.  Partially-burned and dry wood near chimneys can also become more flammable, easier to catch on fire next time.
Surviving one or two chimney fire does not mean your chimney is 'safe' - it just means you're still alive.

Chimneys and chimney-powered stoves have only been around a few centuries.  By contrast, people have been using fire since there were people - thousands or millions of years.
A few centuries is not a lot of time for us, culturally or evolutionarily, to get used to a new technology and develop common sense awareness of what's safe, smart, or best practices.

Here are a few things I wish more people knew about chimneys.
I'd welcome corrections, additions, or stories from others with chimney experience - installers, sweeps, fire fighters, there are a lot of folks with more experience than me, who may have lessons they don't often bother to share any more.

1) Smoke = unburned fuel = creosote. 
We've been using smoke for generations to drive away mosquitos and insects, and to preserve food. 
A lot of people have a hard time recognizing it as dangerous.  Especially since it "smells so good". 
I know it does - I love smoked jerky and roasts, but we make them in a smoker away from the house.  The local butchers lose their business after their smokehouse caught fire, and burned their refrigerated truck and most of their freezer facility.
Smoke inhalation is also one of the reasons for the high rates of childhood mortality in some outlying regions that still use open-hearth fires indoors.  Smoke inhalation contributes to pneumonia in children and elders, and even the able-bodied can develop a nasty cough from the equivalent of a 400-pack-a-day smoking habit.  Smoke from wildfires and winter hearths contributes to health problems including asthma, respiratory disease, and even heart attacks.

The modern American would generally be embarrassed by indoor smoke, but tolerates it outdoors. 
We also have the 'scarcity' mindset, coupled to our "rugged independence" lifestyle.  DIY rural buildings, smaller family sizes where one or two people struggle to maintain a household while working for a living, the push for more and cheaper households full of more and cheaper clutter - all this leads to more expensive heating bills (three couples heating three houses use a LOT more fuel than six people heating one house). 
The chore of filling the woodshed or paying the propane bill falls heavily on more and frailer shoulders.  A lot of DIY chimneys and woodstove installations going up in "tiny homes" and trailers, that may not pass muster in a larger, better-equipped household.  A lot of operators are trying out wood heat for the first time, or to save money, or to scrape by, who don't have time to sit by the fire and enjoy the learning curve. And a lot of families and older folks are trying to heat with wood, but don't have enough people in the house to divvy up evening and morning chores, and still get a full night's sleep.

Smoke is an early warning sign of unsafe wood heat, and an unacceptable pollutant in crowded modern cities and crowded neighborhoods.
If you don't have time to learn to operate your wood fire without smoke, consider sticking with automated heat as a back-up until you're ready for full-time homestead life.

2) Chimney Temperatures: Chimneys draw when warm.  Not just warmer than air, but also warmer than the dew point of any liquids in the smoke or exhaust.  (Clean-burning wood exhaust is slightly heavier than air, at the same temperature.)
- A chimney that puts out wood smoke must be over 350 F to be safe, i.e. in order not to condense creosote/tar inside the chimney.  If you are damping down a fire, or burning wet wood slowly, your chimney is probably also getting too cool for safety at the worst possible time.  Modern US woodstove regulations include a minimum chimney temperature - the chimney must be at least 350 F to safely operate.  Most woodstove chimneys operate between 400-600 F, and some may get hotter.  This is hotter than most kitchen ovens, and more than hot enough to start things on fire if it is anywhere close to combustibles.

- A chimney that puts out a cleaner exhaust (like propane, or coal, or a smokeless wood fire produced by burning dry, cured wood nice and hot) will not have creosote, but will still have water in the exhaust, and the chimney can stall if that water condenses while still inside the chimney. 200-300 F is a typical target temperature for masonry heater exhaust, to stay above the dew point of water for reliable draft.

- A chimney that operates close to room temperature, or below room temperature, is at risk for drafting backwards in certain wind and weather conditions.  All chimneys are likely to have start-up problems if they've been unused for a while.  These problems can be worse on warm days, or in warm climates, compared to a frequently-used chimney in a cold-climate home.
Because regulators understand that all chimneys need to be warm to operate safely (or at all), efficiency comparison numbers on different solid-fuel devices can be misleading.

- Starting Tip: Light a twist of newspaper under the chimney opening "to check for draft" before lighting a fire in any fireplace or woodstove.  Not only does this let you check for the correct damper position on unfamiliar chimneys, it also effectively primes the draft.

3) Good Chimneys, Poor Chimneys:
Size matters.
Chimney draw is proportional to the area of the chimney.  It's also related to the temperature, and the height. 
Clogged chimneys draw substantially less.  Short chimneys draw poorly, especially if they are shorter than surrounding buildings that may cause downdrafts and wind eddies.  Cold chimneys draw poorly, and may even "draw" backwards. 
If you like equations, here's the chimney effect (stack or 'flue' effect): ;

- If your chimney tends to blow back when starting the fire, or on bad weather days, it needs improvement.  Consider doing one or all of these things: 
a) Increase the chimney height to 3 to 5 feet above the roof, and 2 feet above anything within 10 feet (nearby roofs, farm structures, etc). 
b) Insulate the chimney where it passes through unheated spaces like the attic, and where it is exposed outside the building.  Make sure the insulation is non-combustible, and matches the chimney manufacturer's recommended installation. 
c) If your chimney has a LOT of exposed height outside the building (like it went out the wall and then up), you will probably need insulated chimney PLUS a "chase," basically a little insulated house for your chimney.  A chimney chase is a lot of work, and it still may not work as reliably as a chimney that was built indoors, near the roof ridge, to begin with. 

- If you are considering what to do for the size, height, and installation location for a new chimney, think seriously about the following factors:

a) A bigger chimney will draw WAY better.  If you're choosing between stoves with a 5", 6", or 8" chimney, the 8" chimney will be about twice as powerful as the 6" one.  The 6" one will be half-again stronger than the 5" one, and twice as powerful as a 4" chimney.  4" chimneys suck, and probably should not be used except for very, very short runs (like maybe a cookstove in a gypsy wagon).  There is such a thing as too-powerful draft, and too much heat for one room. 
The #1 factor is the design size of your stove.  Most stoves are designed for a specific chimney size, which you can see by the size of the connection collar on older stoves.  Get the right size stove or heater for your needs, and the right size chimney for your stove.
Location, location, location.

b) Treat the chimney right, and it will treat you right.  Many people want to stick the chimney up the outside of the house - to get it out of the way, or in the mistaken belief that it's safer "out there."  An outside chimney still needs to stay warm to draft properly, so you'll probably lose a lot more heat with a slap-on chimney, and you may even end up having to build it its own separate house or "chase" to get it to work adequately.  I prefer to put the chimney as central in the building as possible, where it can stay warm when you're not using it, and where any heat it loses is still usefully lost into the building you're trying to heat.
c) There will be fewer leak problems HIGHER on the roof.  An installation down low, near the eaves, has to deal with all the ice, snow, and rain being shed by the entire roof.  A thru-wall installation has to deal with the rain and ice running down the chimney itself, and keep these leaks out of the wall.  If you must go through the wall, try to exit as high as possible, on a gable side (the pointy side, where there is no drip line to dump roof water/ice onto the chimney).
d) There will be fewer structural problems installing a through-roof chimney than an add-on.  Unless your walls are masonry and your roof is thatch, it will probably be far easier to take the chimney straight up between roof rafters, and it will work better.  Attaching a chimney sideways to a wall, with adequate clearance and weight support, all the way up to the height where it gets reliable draft without building-pressure problems, is more of a job than you might think.

4) Air is not Heat
Chimneys work because they draw all the smoke, and a certain amount of the air, out of your home. 
Any functional chimney will cost you a fair amount of warm air.  Maybe not as much as a smoke-hole in the rafters, but still quite a bit.
Some people resent this loss of warm air, and try to damp down the chimney to trap more warm air in the house for comfort.
If your home is lightweight wood and fluff, and does not have heavy masonry or adobe inside to hold the heat, it is easy to think that losing warm air means losing all the heat out of your house. 
However, warm air doesn't actually hold that much heat - air is much better at removing heat, or preventing heat transfer, than at storing it. 

Consider improving the building's "heatability" - slow down heat losses, improve heat storage.
Hopefully you've already sealed drafts near the floor, and insulated or double-lined any cold windows to prevent the cold-air "waterfall" effect (adiabatic flow).
Next (or first, if you're starting fresh), pay attention to insulation, detailing, and airtight sealing of upstairs ceilings, windows, stairwells, attic hatches. 
Invest in good insulation, especially for ceilings and exterior walls.  (Don't insulate the roof itself unless it's designed for it; insulation inside a vapor barrier can trap condensation on the cold outer surface, causing mold and rot problems.)
For fresh air, consider heat-exchanging ventilation ( has designs you can build with pop cans, if you can't afford a mechanical system).
And as far as possible, within the load limits and rental/lease agreements, consider improving good heat storage within the building in terms of thermal mass or strategically-placed heat reservoirs (hot water bottles, insulated warm bricks).

In a few cases, letting the fire burn out and shutting off the chimney before bed (with no remaining unburned fuel in the stove) may actually preserve more heat than trying to maintain an overnight fire.  Particularly if you're unsuccessful - the chimney will still draw air, although a bit slower, even if the fire goes out.

5) RTFM.  Read The [Friendly] Manual.
What kind of chimney do you need?
What kind of appliance are you connecting?
Would you possibly want to change out in future, say a little woodstove now but maybe a cookstove or bigger heater later?

Modern manufactured chimneys come with instructions.  They are free - and most are available online. 
Woodstoves also come with manuals, even for older woodstove models in some cases.
For lined masonry chimneys, fireplaces, and site-built masonry heaters, some come with instructions, but more often the "instructions" are the building code, and the training of your local masonry tradespeople. 
If in doubt, have a professional inspect your masonry chimney, and confirm whether it's ready to use or needs work.  If you're going to the trouble of building a full-height masonry chimney, it's common practice to include 2 or more flues.

Manufactured woodstoves, appliances, and chimneys are designed and tested with care, to maintain safe chimney temperatures and meet community expectations for clean air, safe operation, and durability. 
If your stove or chimney is not rated for coal (mixed-use or "solid fuel" vs "wood burning), or for burning trash (most aren't, any more), or for a 'banked' fire longer than 6-8 hours, you could easily damage it or endanger yourself by thinking outside the box.
Sometimes people don't want to bother with expensive or complicated chimney installation instructions, and are tempted by cheaper "ventless" stoves and appliances, or by a makeshift workaround vent in the same general style. 
Gas logs are the classic example of an appliance that vents right into the room.  Propane/natural gas cookstoves are another. 
These charming appliances are designed to operate for a few minutes to a few hours at a time, with good ventilation (the instructions on some ventless gas logs actually call for opening a window at least 2 square feet in the room while operating the gas log). If you treat the wrong gas log as an "automatic fireplace" that you can run 24/7, or run an unvented cookstove to keep warm, you risk poisoning the indoor air and/or breaking the appliance in dangerous ways.

Likewise, many modern stoves are designed to operate with specific air to fuel ratios, to cut costs by using a minimal thickness of metal and materials, and to improve sales (sometimes at the cost of safety) by spending the available money on looks not longevity.  While your friend's cast-iron stove may be able to burn coal, trash, or hold 'banked' coals overnight, trying the same trick in a different stove can cause serious problems.  RTFM.

Some wood stoves are designed as "camp stoves" or "space heaters."  Some "camp stoves" I've seen are so thin-walled that the makers expect them to burn through within 3-4 years.
Some space heaters are super-basic like a little black box; others are designed with beautiful trim, enamel, glass, low-clearance double wall construction, and general showmanship as a "fire TV" for your parlor or rec room. 
But a "space heater" is still, at its core, a parlor heater or one-room heater.  It is designed to heat while you are in the space with it, not to heat a whole building evenly, and not necessarily to perform automatically while you are gone. 
A space heater will not give the same performance as a whole-house heater, furnace, or boiler. 

It pays to read the product specs, not just the price.

Look for the BTU output, not just the generic "square feet." Square feet are a salesman's number; your realtor and your floor showman speak this number, but it is almost meaningless when it comes to heating performance.  It would mean more to look at last winter's heating bills, or run your home's details through an online heating calculator like this one at

If you want to know the max. BTU output you'll need on the coldest night of the year, use your USDA zone (average extreme low).
If you want to do some math and work out the amount of wood or propane you might burn in a "normal" year, use your Heating Degree Days (HDD) for your local area, or compare last year's bills.  Wood has a lot less energy per pound than oil or propane, so you may be surprised how big a woodshed you need to properly dry and store enough wood.

If they have brick or soapstone tiles "to hold heat," look at the actual thickness of material. 
Rule of thumb is maybe 1" per hour - so a brick liner 1" thick might buy you an hour or two of extra heat.

If you want to cook on it, or build around it with masonry, or heat water with it, or install a damper for air control, make sure that's included in the original manufacturer's design specs.  Call them if you need to, before buying or altering your stove.
One of our favorite sources for general info on wood heat, and stoves, and all things chimney-related is the Chimney Sweep's Library,
A Historical Interlude:
The whole idea of sending the smoke out a chimney, rather than using it to heat the walls or kill insects, was have been a bit of a novelty originally. 

Look up the original meaning of "curfew", and some of the early fire-prevention regulations in Europe and Japan. 
There was even a rule in Ireland that people had to light a smoky fire once a year, and trap the smoke indoors, to fumigate the thatch.
Viking-era homes, like pirate ships, usually had a central hearth where a box of sand held all the necessary tools, including the tripod or trammels to hang pots over the fire.

Victorian cast-iron foundries turned out dozens of "brilliant" heat-saving add-ons for chimneys - from swooping sections of stovepipe designed to snake along the ceiling before exiting the room, to Escher-like heat exchangers with honeycombs of cris-crossing flue pipes.  The biggest problem with all these clever heat-exchangers is they did their job too well: extracted heat from the smoke and, incidentally, helped that smoke to cool and condense into creosote.  Although creosote may not catch on fire for months or years, eventually some cold winter day, someone is going to build a bigger fire, or the last little dribble of creosote is going to reach the wrong part of the stove underneath.
A creosote fire in a curving, long stovepipe section has a distressing tendency to pop it open like a flaming seed-pod, spraying creosote-dripping flames all over supports and ceilings. 

Times change.

If you're going to the trouble of putting in a new chimney, it's worth reading up on the latest specs and recommendations.
There are a couple other home improvements that might be worth considering.

Fire Without Smoke:
- if you need more heat, and particularly overnight heat, have you looked into masonry heaters or rocket mass heaters instead of a conventional wood stove?

They are less well known as yet, but I would love to see more of these tiny masonry heaters become "normal."
Donkey's latest has a lot of charm:
This example heats a 10x30 mini-cabin. 

For bigger structures, you can find gorgeous professional examples on the Masonry Heater Association website (
DIY masonry heater plans are available using with brick (see David Lyle's Book of Masonry Stoves, the back has Russian bell stove plans), with earth and pipe (rocket mass heaters), with combinations of brick and steel (see recent designs called "sidewinder" or "cabin stove", or even with raw adobes and scrap metal.  
Professional installation for any heater or appliance is going to bring the price up, and more so for a site-built project than a quickie installation job.  But there are ways to spend time instead of money, if you really want one.

The main advantage of a masonry heater is that it store heat in masonry mass, so you burn a few hours per day, and you can shut down the chimney draft in between fires.  Saves heat, saves fuel, and saves the worry of "operating" a woodstove while you sleep. 
The main disadvantage is they're huge (in proportion to how much heat you need to store, and for how long).  So it's a bit of trouble to build one in a house that wasn't laid out with masonry heating in mind; more of a remodel project than replacing a standard appliance.

House as Chimney:
- if you are struggling to keep the house warm on a budget, have you considered an audit or inspection that includes the upper part of the house? 
Many people take steps to chase cold drafts at the floor level and windows, but don't realize that a lot of the problem comes from upstairs or ceiling leaks. 
Just like the chimney, a warm house will tend to move air upward and out, through any available openings. 
A good energy audit may recommend sealing attic hatches and behind the ceiling trim, insulating the ceiling (but not the roof, unless it's designed for it), and making sure upstairs windows are just as leak-proofed as downstairs ones.  Occasionally they may find other leaks; hot water leaks are particularly costly, and sometimes electrical appliances can lose significant energy. 
A reputable energy auditor, especially a third-party one who isn't just selling one flavor of weatherstripping or insulation, can help you locate heat leaks with an infrared camera... or you can get your own that attaches to a smart phone for a few hundred bucks, which is a pretty cool Xmas toy for the techie.

The basic concept is, you don't want your house drafting like a chimney.  You want it to trap heat, like a nice winter hat or old-fashioned chafing dish (covered). 
You and your building probably need to breathe a bit, but you don't need to wander the world bare-headed to do so.

House as Oven:
- Some of the original "black stone" dwellings of the Neolithic England did not have chimneys.  Or they were chimneys, depending how you look at it.  The house was built like a classic beehive, with a low door, except that instead of straw it was stone and earth, and instead of bees it was sized for people.  A central hearth fire heated the whole structure, the low doorway helped trap most of the smoke inside, and people presumably spent most of their indoor time sitting low to the ground, breathing the relatively fresh air available below door level.  In warmer climates like Greece the top had a smoke-hole; in some colder areas like the Hebrides, there would be a conscious effort to trap the smoke and not let it escape.  The stone of the house held heat from the fire, radiated it back down into the space, and people presumably figured out how to time the fire and bank it at night so they'd get sufficient fresh air.  A bit like an oven, for people.

- The origin story for the Chinese masonry heaters / platform furnaces known as k'ang says that the earliest cave people heated their caves and food with a fire on a big flat stone, and at night, they would sweep aside the fire and ashes, and sleep on the heated stone.  A bit like a pizza stone for people.

Does this sound dangerous?
Wouldn't you asphyxiate with a smoke-line down to 3' off the floor? 
Wouldn't you burn yourself if you went to bed too soon after cooking dinner?

As David Lyle put it when discussing braziers (like putting a Hibachi under your bathrobe or tablecloth to keep warm), "... much the same as with modern automobiles: It is great if used correctly, mistakes can be fatal.  ...  The ancients knew very well how to use braziers safely.  Nevertheless individuals sometimes failed to do so; they did not bother, or had too much wine and forgot, and so died.  Much the same might be said today of automobile drivers, or wood-stove users."

Some people say "safety obviously comes first, cost is secondary" but absolute safety is hard to actually find.  Roman brasiers were very similar to modern wood stoves (some had water-heating pipes, or air vents underneath, or other features).  All they needed was a chimney.

The chimney doesn't really come into mainstream use until the industrial era - when bricks, chimney flues, and other industrial components become widely available.  You might think that understanding the science and physics involved was a factor - but a lot of modern chimney codes come from hard experience, not scientific forethought.  I think one of the biggest factors in widespread adoption of chimneys is that not only were energy-intensive industrial parts more readily available, but there was more and cheaper energy available for providing the extra heat needed to safely send smoke out the chimney instead of 'saving' it inside the cave/hovel/house. 

I don't know when we started to feel that smoke inhalation was a peril worth the cost of a chimney to avoid. 
Collectively, we still haven't decided that smoke-free lives are worth the cost of a good stove, or a masonry heater, or public funding for wildland forest management.   So you might say we're still not 100% there yet.

Finally, once you have a properly installed chimney, and have checked that it's a good match for your stove and heating goals, there is the question of maintenance.
6) Chimney Maintenance:
Annual inspection, and cleaning if needed, is the industry standard.
Some people recommend monthly inspection during the heating season ... if you have to remove creosote that often, you're probably burning dirtier than you should be.

If you sweep your own chimney, especially if you haven't been trained how to do it, it's easy to think you're fixing the problem when you might be missing the warning signs of a chimney fire.
Creosote is generally a bad sign - and it can be hard for a novice to distinguish between soot, 'crunchy' creosote, and the residue from a chimney fire that burned sticky tar into black bubbly leftovers.

Consider having a professional chimney sweep do an "annual inspection" once or twice, and asking them for a quick inspection lesson.  American chimney sweeps may not be quite as knowledgeable as the ones in the Netherlands who are the legal authority charged with approving new stove installations, but most of them have seen a lot of good and bad installations, and they may be able to recognize an accident waiting to happen just in time to prevent you learning your lesson the hard way.

Be safe.
Warm wishes for many nights of lovely, trouble-free, fireside snuggling over the holidays.

Erica W
2 months ago

Travis Johnson wrote:

Roy Clarke wrote:I think wet wood is a bad idea. It will cool the gases (fuel) and send them up the flue as tar. The tar will condense until, one day you will have a chimney fire.

That is making the assumption that the homeowner does not brush out their chimney. I have never had chimney fire, but then again someone mentioning making sure to brush out their chimney once per year. I was rather shocked. I brush out my chimney once per MONTH in the heating season, sometimes every 2 weeks depending on what I am burning. (Right now I am burning green cedar because it has been fairly warm outside and I just need to take the chill off, so I brush about every 2 weeks.

But every time I build a chimney, I make sure it is very easy to clean out, because one that is easy to clean is one that gets cleaned. No creosote build chimney fire.

I agree, wet wood is a VERY bad idea.  I feel the same way about green wood.

If you have to 'brush out' your chimney multiple times during heating season, you are depositing a lot of creosote - hopefully, it's the chunky, brittle kind, not the sticky-tar kind.
Brushing won't do much to remove sticky creosote, until it gets hot enough to re-cook and/or burn. 

And I definitely don't like the idea that some people "clean" their chimneys by having a chimney fire.  (Nobody here has suggested this, but it's come up in other conversations with locals.)

Chimney fires suck.

As a volunteer fire fighter, one of our worst fires last year was a couple who had just cleaned their chimney. 
It caught on fire anyway - possibly some of the creosote got dislodged and settled down at the bottom closer to the heat, possibly some part of the chimney got bumped and ended up with inadequate clearance to the wall or ceiling combustibles, or maybe a piece was damaged enough that the cleaning broke a joint loose. 
There was not much left of the chimney, or the wall for that matter, for us to find out more for sure.
Both occupants were on site, had time to move some belongings out of the farthest rooms of the house, but the room with the stove in it already had fire rolling across the ceiling, and the whole structure was a total loss.
He was trying to laugh it off with black humor, she was still shaking from hearing the cat dying in the attic.

We did what we could, with volunteers from the two closest fire districts, but it wasn't much we could do. 
We had to finish the job with shovels and buckets of ice, as it was -10 F and the fire trucks were freezing faster than they could pump water.

That incident really stuck in my mind.
It was the 3rd or 4th chimney fire in 2 years, in a district with only a few hundred year-round residents.   (It can be hard to tell a "woodstove fire" from a "chimney fire" if the residents weren't home when it started.)
1% per year does not seem like very good odds on chimney fires. 

I now look at both visible smoke, and mid-winter chimney cleaning, as early warning signs of a possible, catastrophic, chimney fire.

It's not that cleaning it is a bad thing - it's a very good idea. 
However, I can't forget the look on my neighbor's face saying "I just cleaned it" while his house is burning down.

If you know your stove produces creosote the way you run it, and you know this is a bad thing, then cleaning the chimney more often is basically a band-aid. 
I do recommend hiring a trained chimney sweep in to inspect at least once, and show you what to look for.  Some stoves are fine with once-a-year cleaning.  Some stoves do build up fly ash faster.  Peter van den Berg told me about inspecting a Swedish contraflow stove (masonry heater) he'd helped build 17 years prior, and finding out the owners had not cleaned it once in all that time. 

If your inspection shows creosote- not just powdery soot and fly ash, but little crumbly chunks or drippy dribbles of creosote - then you are perpetuating a situation that could lead to a chimney fire sooner or later.
Creosote in any form is an early warning sign of a preventable emergency.

The fundamental problem that causes creosote buildup is running incomplete combustion, in a chimney cold enough to condense the creosote from the smoke. 

Creosote is a very common thing for people to achieve as a side effect, when their goal is "keeping a wood stove going all night."

If your goal was "keeping the house warm all night," or even better "keeping my family warm all night," I have all manner of suggestions, from the frugal to the extravagant, no creosote required.
- masonry heating
- home energy audit / heat loss mitigation
- summer/winter heat design (beyond passive solar)
- personal comforters
- personal heat reservoirs
- home heat storage reservoirs
- saunas, holiday foods, and other lifestyle tricks from the frozen North...

The other scenario that is even more horrifying are the folks who tell me, "oh yeah, we used to have a chimney fire 2 or 3 times a year, my dad would be up on the roof yelling at us what to do." 
THIS IS HORRIFYING.  Please never do this.

If your chimney is well-maintained and well-installed, your house might survive a chimney fire a lot longer than one that was installed wrong, or not maintained.  But it's not the same as "safe."
Modern, manufactured chimney components are designed to take ONE chimney fire without failure, but repeated chimney fires will weaken the parts, loosen the joints, and degrade critical insulation and safety clearances.

I just moved a bunch of this post to a new topic, How Chimneys Work, because it's not really on point for the original post on this thread.
I do think that understanding how chimneys work is vital information to safely operate a woodstove, fire place, or any chimney-equipped heater.

If anyone is successfully keeping a wood stove going all night without causing creosote to build up in the chimney, I'd like to hear your methods.

- Is your wood stove the right tool for the job? 
Most wood burning stoves, especially the cheap ones, are sold as "space heaters," not as a whole-house furnace or heater.

If you have reasons for wanting a light-weight woodstove (under 1 ton) instead of a bigger wood-fired furnace or masonry heater, and you want overnight heat from it, check the specs.
Look for wood stoves that have been tested and rated for a nice long burn. 
Full-sized fire brick liners, or soapstone tile, or heavy iron bodywork might be good indicators of a sturdy stove, built to heat not just for looks.  But the real deal-maker would be the number of hours it's rated to sustain its long burn, when it was certification tested.

Don't be too quick to dismiss masonry heaters for cost or size.  A tiny masonry heater can hold heat all night, and you don't have to keep it burning all night.
Donkey's latest has a lot of charm:
We slept with it for the first week or two after it was built; we'd fire it 4 to 6 hours and then have to stop, and it held the room above 65 for at least 12 hours afterwards.

How much wood could you save if you only had to run the stove half as long/half as often?
A savings of 6+ cords per winter could be $900+ in your pocket each year, or 50+ hours of work you don't have to do between day jobs to prepare for winter.

What is a good stove worth to you?

But this is not a thread about switching to a different stove or heater, sorry.

Do check the specs on your stove, however.  Not all stoves are built equal.
If your model is just not designed for overnight heat, you may want to upgrade, or consider using the backup heater for night times if you have one.


Not all solid fuels are the same.
Some wood stoves are dual-purpose by design; others are not intended for coal (or any other fuels).  A very different/wrong fuel could cause warping, chimney damage, or problems with CO and draft. 
Coal takes more air to burn clean than wood, and can put off a different set of gases.  Dirty coal (the kind with sulfur) was discovered to have weird effects on some types of mortar/chimney cements.  I've seen photos of older masonry chimneys bending to one side, due to which part got more exposure to the sulfur/acid in the prevailing wind. 

If your stove is not designed for burning coal, you might still be able to use wood charcoal for a cleaner burn.
(There are bigger versions of the TLUD that produce charcoal while you cook on wood gas.) 

Charcoal seems like a safer alternative to using green or wet wood as the last load of the night. 
Charcoal can still burn dirty, with CO and organic acids in the exhaust, but you should get less of the really nasty, sticky, sappy volatiles that contribute to the worst creosote problems.


The whole question of what to burn, unattended, while your family sleeps  - I have to admit it kind of gives me the willies.

Having experienced thermal-mass heat, and passive solar heating, I don't think I will go back.  I've camped in the snow with a good foam mat and a sleeping bag.  
I don't really like the idea of any fire burning unattended while I sleep. It even makes me nervous leaving electric cookers or pipe heaters on unattended.  (Rodent+wiring is another fire scenario I've seen and would rather not see again).

I can admire the art of keeping coals alive from the fairy-tale days, of big Russian ovens big enough to shove a witch into, and new fires once a year at Easter. 
But I am happy to live in a part of history where both masonry and matches are cheap.

So I will leave the rest of this thread to others with more relevant experience.
2 months ago
Very cool! 
Great to hear what you're up to.

Are you selling these yet, or still prototyping?

I see your website ( has plans and the super-hot core, but I don't see the aluminum series.
Care to share a link?

2 months ago
Standard building brick usually works on an 8" modular pattern once you add mortar... 3 courses is 8 inches tall, 1 brick is just under 8" long (with mortar, they are 8" apart), and 1 brick is just under 4" wide.

Our bricks were the 3-hole kind, I'd guess they were 3.5 x 7.5 x 2.5 or so (I'd go with "Standard Modular" from the chart above, but they could have been Standard or Series 70, I suppose).

Because of the small size of the fire, and the chimney, the heat extraction balance is critical. 
This heater performed really well in that respect - once dry, it put enough heat out the chimney to get reliable draft, and the chimney was touchably warm but not excessively hot.

Donkey talked about making it a little longer, to have room to center the heat riser - but if you did that, you'd also have more extraction surface.
I might suggest also raising the firebox if you did lengthen the body, to balance out the surface areas, and to make it more convenient to load and operate. 
Ernie had trouble getting the fire started properly (people commented on the smoke on two different occasions) because he is tall, and unable to get down on his knees due to old injuries.

Rough guess as to internal SA based on the pictures:

Main Heat Extraction Surfaces of Bell:
The firebox moulding fills up the first few courses, up to the height of the 'arms' in front by the door, back to the heat riser.
Above that, it's 9 horizontal courses before the bell, and internal dimension is 3 bricks (omitting the half-brick wall thickness front and back), by 1.5 bricks.
So the inside of that chamber would be about 24" by 24" by 12".  SA = 2(24x24)+2(12x24)=1728 sq. inches. 

The inside of the dome is 6 brick-edges tall on each side, by 24" long, so roughly (16"+16") x 24" = 768 sq. inches
The end caps of the dome look to be maybe a square foot each, rough guess, or 300 sq. inches total.

Total of the inside bell surface areas: 2796 square inches, or 19.4 square feet, or 1.83 square meters.

Lesser Extraction Surfaces:
Not sure whether to count the firebox top; that would be an additional 12x24=288 sq. inches.

The heat riser is in there (8" cylinder, extending from the floor up to the rim below the arch); exposed SA about pi*8*24=602 sq. in.  
Not sure whether it counts for surface area; the mix of that and the firebox looked dense enough to store some heat, but they also function as insulation.

Beside the heat riser, the path going down to the chimney is also about 8" long by 4 or 5" wide by about 12" or 13" tall. If we count it, it's roughly 12" by 24" total, another 288 sq. inches
I think Peter sometimes doesn't count the bottom surfaces due to lower temperatures, so we may be able to omit this too.

If we did count all those surfaces too, then we'd have another 1178 square inches, or 8 square feet, or 0.77 square meters.
Total would then be 2.6 square meters / 27.5 square feet / 3974 sq. in.

Plus a bit for the firebox itself, if we like.  That was 18" deep by about 8" tall by 5" wide, so 380 sq. inches or so.
I believe this is usually not counted - however in this build, I think that block of refractory at the bottom was a significant factor in holding heat through the night.

Another calc we could do might be total mass of the system.
A cubic foot of this dense building brick weighs about 125-150 lbs.  A cubic foot of brick would be about 20 bricks. I'll go with 135 lbs/cu ft for estimating.

13 courses x 13 bricks per course + 6 bands x 8 bricks per band = 10 or 11 cu ft of brick.
+ 1 cu ft arch ends and wedges
+ 2 cu ft firebox and heat riser (I'm counting a 5-gal bucket of mix as 1 cu ft. for estimation purposes)
= total of about 14 cu ft. of masonry in this project. 
Thermal Mass (without footing)= 1850 lbs = 0.9 Imperial tons or 0.8 metric tons / 840 kilograms)

Incidentally, for US code purposes, this would definitely qualify as a masonry heater (over 1500 lbs per the US standard description). 
However if someone wanted to build a pre-fab model, it could also squeak in under the definition of a wood burning stove (1980 lbs max). 
If you can pin all that masonry together for shipping, and add a door, and replace the footing brickwork with legs, using not more than 130 lbs of additional steel.

Again, the performance of this stove was lovely - the surfaces got very hot, but not dangerous to touch (a little hotter than I'd want my bath water, however the brick and plaster are less conductive so it was not painful to touch).  Heat storage is figured on mass x heat capacity x difference in temperature, so the hotter you can get the mass (within safety limits), the more heat it stores. 
Donkey really nailed this one, I don't think it would be improved with either more mass, or less mass.  It's probably within 2  cu ft of absolutely optimal, and may be optimal as-is.

I will be interested to see how it does with its final coat of high-fiber plaster... I anticipate that will give it slightly more mass, insulate the existing mass for a slightly higher internal temperature without causing the external temps to become uncomfortable, and may slightly extend the heating curve later into the mornings.

2 months ago
Here are a couple of articles on the methods used in North America:

(I'm guessing that in Chile, you have a lot of the Central/South American masonry methods, and some of the materials and techniques for cold climate conditions may be less common.  However your southern climates are definitely cold enough to benefit from them.  Eurasia still has the advantage of big smeared-out regions of similar climate zones, where a design like your Chinese greenhouse can be copied from east to west.  Chile has the opposite situation, being smeared out from north to south where the appropriate solution in one region may be useless to other regions.)

For those who haven't seen it already, my new favorite article on what a building IS, "001: The Perfect Wall."

I agree with those who have suggested enclosing the space under the floor, by any means necessary.  An exposed floor can have colder temperatures than the outdoor average, due to being shaded, whereas an on-ground floor typically benefits from the soil's stored heat.  Ground temperatures below the surface gradually approach the annual average temperature.  So in my climate, it can be -10 outside and still 40 or 50 degrees F (15 C) in the ground under the house. 

Unless you are storing valuable things in the space, or someone has convinced you to build the house in a hole without adequate drainage, the small amount of added moisture exposure will be less of a concern than the constant heat loss.
In fact a colder surface under the building can contribute to moisture problems, through condensation of indoor moisture (or leaks) in the cold, outer layers of the building materials.

One advantage of the perimeter wall is you have a lot more ways to build it.  You don't need panels if local labor is cheaper.

For a low-tech, possibly local enclosure solution:
You could potentially use a 30-cm foot of dry stone, or concrete block or brick (anything that won't allow moisture to travel upward).
Then use earthen brick or cob (with a LOT of straw and a little clay-mud mixed together) above that.  Monitor to ensure that there is no wicking of moisture up from the ground. 

Another option is to get perlite and mix it with clay or cement, to make insulating cob/concrete.

Even a skirting of wood without insulation will slow air movement, reducing heat lost to evaporation and colder air temperatures.

Part of our home is suspended floors, the rest is on a concrete slab, and every layer we add to our perimeter around the sub-floor space has been worth it. 
Our climate is Okanogan / Okanagan Highlands, USDA zone 4-5, winter low temperatures sometimes as low as -25 F (-30 C), and summer highs up to 105 F (40 C). 
Our valley gets about 12 inches of rain per year, on average; however we rarely have an 'average' year (more common is alternating extremes).
Your problems with temperature may be less, and with damp possibly more, if your climate has marine influence.

Erica W
4 months ago
I've included your post in that forum.

You might also want to post in the appropriate regional forum, for folks looking to connect in your area. 
Seems like folks from Kentucky are posting in the "Midwest, USA" forum.  You might even see an opportunity you like there.

4 months ago
Here are a few images from the L-shaped projects.
(These plans are still marked "draft," but enough people have expressed interest that we're letting them out of the bag so you can get on with your project planning.)

5 months ago