Topics to Explore
Topics to Explore front end alignment Next Book Solar Farm in a small space Minimum
area needed to grow food Body heated space Illustrations Heating Systems Cheap and
simple solar house Cheapest food ever my new heat pump -personal experience
Extreme Garage sale jaunt The Theory of avoided costs New Sources - recently
discovered ZCL last cuts from Book ZCL Cuts Medicaid eligiblity and ZCL
Topics to Explore
Here is a list of topics that the book did not, could not adequately consider due to space
limitations that I intend, in the future, to expand on here:
Extreme Thrift: chapter 2:
Fine points of foraging and dumpster diving. especially more on legal ramifications and
Homeless: chapter 3:
More detail on safe places and methods to set up an urban camp.
Homesteading: chapter 5:
Detailed design ideas for hydroponic solar greenhouses using recycled materials. For
example: use of recycled plastic containers for plants in arrangements that assure
adequate water-nutrient flow through these containers. (A 'Mittlieder' style fill and flush
system may work - rather than the continuous flow method of many hydroponic systems).
More designs for 'short log cabins' incuding attached solar greenhouses and storage
Detailed plans for 'body heated spaces'. (This has been added to the new edition of my
More precise calculations for area needed to grow food for one person for one year. (This
has been added to the new edition of my book).
Comfortable Living: chapter 6:
Framing and floor plans for a ZCL suitable house.
Frame design - and design details for a tandem rider - safe small car.
Society Practicing ZCL: chapter 7:
Design for a universal factory.
front end alignment
front end alignment - zero cost
Here is a do-it-yourself, zero cost front end alignment paraphrased from How to Repair
Your Car by Paul Brand: called a racetrack alignment or ‘stringing the car’ because
during car races when the expensive alignment equipment is not available and an
alignment is needed, string is used to perform the alignment. The procedure is detailed on
page 154 of his book obtainable at libraries.
Here I’ll summarize it: Start on a flat level surface like a garage floor. Point the steering
wheel of the car straight ahead and roll the vehicle back and forth a few times to make
sure the front wheels point straight ahead. Wrap fishing line once around the car at the
level of the center of the tires. Pull it tight and tie it off. Pull the line away from each
wheel and slip a 2 inch diameter pvc pipe up against each tire in vertical position centered
on the tire. The pvc pipe must be long enough to rest on both bulges of each tire.
Use a 6 inch ruler to measure the distance between the fishing line and the tire sidewall
bulge of each tire at the front bulge of each rear tire and the back bulge of each front tire.
The front pair of measurements should be the same. Also, the rear pair should be the
same. If so, you know the vehicle is square and the front-end wheel alignment setting or
toe in are the same. Now you must check the toe-in. Chalk or tape mark the exact center
groove or block on the front of each front tire just below the chassis. Then with a tape
measure, measure across between them. Then roll the car until the marks you made are on
the back side of the front tire just below the chassis. Measure again. For most cars, the
difference should be 1/16 of an inch wider on the back measurement if the alignment is
correct. If not correct, you must loosen clamp bolts or jam nuts on the steering tie rod and
adjust their lengths until they are correct. You must re-measure with each adjustment to
assure the distance is the same from string to tire bulge for each front tire. If not, you
must continue to adjust the tie rods until correct toe-in and tire-to-string distances are
I am outlining a new book expanding on one part of ZERO COST LIVING to be called:
SOLAR FARM ON A HALF ACRE OR LESS (Or possibly 'Solar Homestead') I believe
this concept, outlined in ZCL, deserved an entire book. In this new book I intend to
provide more detailed plans for a farm no bigger than a suburban or even a city lot.
Believe me it can be done.
As described in the book, the Solar Farm is an example of a fully realized 'Personal
or 'P.E.' equivalent in the economic world to the Personal Computer or 'P,C,' in the
Just as the P.C. took the computer out of the hands of the mainframe computers of the big
corporations and put the computer into the hands of everyone, the P.E. will put the
economic system into the hands of everyone, thus freeing folks from dependence on big
business and corporations, whether for jobs or products.
A Solar farm able to provide the residents with all of their food and energy needs could
be created on less than a half acre and I will devote a part of the book to discussing just
how small an area may work for a solar farm.
Here is a peek at that discussion:
Theoretically, with photvoltaic cells now able to operate at a (claimed) 18% efficiency
maybe 1,200 square feet of solar cells could provide enough electricty for home and car
and a small surplus to sell to the utility if efficent appliances are installed in the home.
Also a thousand square feet of solar hydroponic greenhouse could provide enough food
to eat and sell and a surplus for extra income. For example such a greenhouse might grow
10 pounds of tomatoes or lettuce per sqaure foot per year, saleable at $1 or more per
pound. So 1,000 sqaure feet may yield you $10,000 per year - a decent income if yo are
practicing the other techniques of extreme frugality.
So a 2000 square foot lot (with your house under the photovoltaic cells and your
hydroponic solar greenhouse attached to the south side) could be large enough to live on
in comfort. Zoning may have building setbacks of 10 feet on the sides and back and 40
feet in front - but still a lot of 60 x 100 feet or 6,000 square feet would accomodate these
requirements. And, if setbacks are less - 5 feet in some locations (and even 0 in some
places) you could live on a very small parcel of land.
Solar Farm in a small space
Solar Farm in a small space
SOLAR FARM - Minimum Land Area
An interesting question, to me and possibly others considering a solar farm is, what is the
smallest area possible that can support a family (in this case a family of 4 people).
After thought and calculations here is my estimate. From my book, 550 square feet is
needed to support one person with enough food for one year give 2 pounds of food grown
per square foot and and about 1,100 pounds of food needed oper person per year (3
pounds per day). So 2,200 square feet of land area is needed for food. A lot of only 50 x
50 feet would be enough.
Now what about a house and accessory buildings? Possibly, put the house and any
accessory buildings up in the air over the garden along the north side of the lot so the
house does not shade the garden. The house would necessarily have to be narrow, perhaps
12 or 14 feet wide. But wait! The roof of the house could be a garden area also if built
strongly enough and designed to be walked on. (I must admit however I don't like flat
roofs. I like simple gable roofs. The roof should at least be, I believe, gently sloped, so it
can be walked on but still drains adequately. Maybe a 5 or 10 degree pitch or perhaps 10
to 1 pitch).
If you have a bike and no car then virtually no parking space is needed.
Or possibly a car could be parked under the house using a 10 x 20 or 200 square foot
space. With a garden is growing on the roof of the house no space need be lost to parking.
So 2,200 square feet is the minimum, right?
Wait a minute! (again). What about solar greenhouses. A solar greenhouse, using
hydroponic growing methods; could produce 5 times the produce of a garden, or maybe
10 pounds of food per square foot over a year. So 1,100 pounds of food per person per
year times 4 people would require, for 4,400 square feet, only 440 square feet of growing
area. Add some area for produce to sell to pay property taxes and other expenses - maybe
another 440 square feet growing 4,400 pounds of produce worth $1 per pound (for beans
or more for other crops - much more for some crops) so $4,400 would be earned by this
method. Enough for most other living costs in a 'Zero Cost Living' lifestyle including
seed, fertilizer, electricity (unless you have photovoltaic panels).
A small simple basic car, easy to repair, getting high miles-per-gallon might almost be
affordable with this greenhouse area. At a minimum such a car would require $1,500 per
year for insurance, repair, legal fees, and fuel.
However, possibly the car could be fueled by rooftop photovoltaic panels and (if a
hybrid) fuel from biomass (biofuel) perhaps methanol produced from plant wastes.
You may want to get your plant wastes off site, saving your onsite wastes as mulch and
compost (if you use some organic farming methods).
But won't your photovoltaic panels shade your greenhouse? And how much area would
be needed for these panels? That is a question I will consider in later.
It would still be much simpler to live where you can get everwhere on a bike, avoiding
the costs, complexities and headaches of a car. The $1,500 (minimum) you need for the
car could be used for vacations or saved for emergencies or ?
In conclusion (for now), excluding area for photovoltaic panels: If the house was entirely
beneath the garden, and the greenhouse covered the entire roof.
possibly under 1000 square feet of area could support a family of 4 living with extreme
Minimum area needed to grow food
Minimum area needed to grow food:
How much space is needed to provide one person with food for one year?
The short answer to this question is surprising.
In a solar greenhouse: 110 square feet
How did I come up with this area:
From my book, a person needs about 3 pounds of food per day and about 1100 pounds
per year. In a garden growing 2 pound sper square foot, 550 square feet of area is needed
to feed one person for one year.
But wait. A hydroponic solar heated green house could produce 5 times as much food per
square foot or about 10 pounds per square foot per year. Therefore, 1100 pounds of
produce could be grown in an area of 110 square feet or 11 x 10 feet.
This is a theoretical estimate. Actual production will depend on the design, efficiency,
operation, management etc. of a solar greenhouse.
I will expand on this in the future. J.R.D
Expansion: After further consideration I realized this is wrong. The weight of food eaten
is not the key factor. The ENERGY CONTENT of the food you eat determines the food
needed per year.
110 square feet would work if you grew and sold most of your 1100 pounds of food at $1
or $2 per pound - perhaps growing lettuce and then using that money to buy food with a
higher energy content. If you earned $1100 or more that could be sufficient to buy all of
your food for a year: using the $1100 to buy grain or beans or rice or other high energy
(but low cost per pound) content food.
To actually provide all of your own food yourself , growing beans I estimate you would
need 670 square feet of greenhouse space - based on the energy content of beans and the
solar energy conversion efficiency of beans to edible food.
How do I come up with this number.
I will convert calories to Btu or British thermal units because it is easier for me to use this
unit of energy for all calculations. One food calorie is actually 1000 ordinary calories or
one kilocalorie (the dirty secret of the food industry).
One Btu equals about 250 ordinary calories.
One person requires about 3000 food calories per day if eating for health and moderately
active. 3000 food calories equals 3,000,000 energy calories per day divided by 250 equals
about 12,000 Btu per day.
12,000 Btu x 365 equals about 4.4 million Btu per year.
Field grown beans convert solar energy to food at an efficiency of 0.33% or 1/3 of 1 %.
In a hydroponic solar greenouse assume 5 times field grown efficiency or 1.67%
Solar energy gain in the midwest is averages about 450,000 Btu per square foot per year
so a 1000 square foot greenhouse realizes 450 million Btu of solar energy. One percent of
this amount is 4.5 million Btu. 1.67 percent equals 7.51 million Btu.
But you only need 4.4 million Btu per year so the greenhouse can be smaller than 1000
square feet - about 1/3 less or about 670 square feet.
Therefore a hydroponic greenhouse of 670 square feet growing beans might provide
sufficient food for one person for one year.
Doing these calculations for corn, which is only 0.25% efficient or one fourth of one
percent you come up with about 880 square feet.
Doing these calculations for wheat which is only about 0.1% efficient or one tenth of 1
percent you come up with about 2,200 square feet.
For spirulina Algae at 25% efficiency in converting solar energy to food only 88 square
feet of solar greenhouse would be needed.
But consider, as described at the start of this discussion a greenhouse of only 110 square
feet, producing 1,100 pounds of food or 10 pounds per square foot per year - produce that
could be sold for $1 per pound could yield $1,100 - enough to buy low cost high energy
foods for one person for one year: 25 pound sacks of grain at 50 cents a pound for
example, or dry beans for $1 per pound.
110 square feet, the size of an average bedroom. Not much space really.
Body heated space
Body heated space
After reconsideration I have realized that the body heated space calculations and
estimates used in the first printing of my book are not correct. Specifically, one person
could produce 1,500 Btu per hour or 36,000 Btu per day only if he contuously did
strenuous exercise for 24 hours. If this were possible, his food requirements and cost
would tripple over a usual 3000 calorie a day diet.
Trippling your food requirements (and exercising 24 hours a a day) are not the way to
zero cost living.
Correct would be 500 Btu per hour and 12,000 Btu per day, the energy output of a person
at rest. (Exercising in your body heated space could provide a few more thousand Btu).
TO achieve a body heated space with this energy amount is still entirely possible, but not
with a 120 sqaure foot space insulated to R20 (U 0.5) and a temperature difference of 30
degrees (25 f to 65 f) In my reprint of my book I will include a corrected design for a
body heated shed, or room in a house - with an illustration.
Basically insulation must be increased - straw bale walls would provide enough at R 40
(U 0.25) and/or some heat energy must be tapped from the ground (always at 45 f to 55 f
at several feet below grade) as in the 1980's designs for "double wall thermal envelope
As my design illustration will show - a pretty neat and practical structure about the size of
an average bedroom could serve as a body heated space. Connect a group of these
together with shared bathroom and living room/kitchen - and you could have a
moderately sized house heated entirely by the bodies of the occupants. 4 people could
body heat 480 square feet. A larger shared living room and kitchen with a very modest
rocket stove (as Ianto Evans describes in his book) and you are well on your way to a
very inexpensive comfortable zero energy house. (Zoning codes may require 900 or 1000
square feet minimum house size so the kitchen, living, and a bath might equal about 500
square feet - a 25 x 20 foot area). Windows oriented to gain solar energy (with insulating
shuttters) and thermal mass to store collected solar energy could reduce the need to use
the rocket stove to the coldest days of the year.
Now attach hydroponic solar heated greenhouses to this structure - for food and more
heat energy and you are well on your way to a very inexpensive homestead suuitable for
zero cost living.
Here are 3 illustrations from my book and the front and back covers.
Note that the top two illustrations will be in the revised first edition coming out in about
two weeks (Mid November 2009) - but are not in the current edition. The
5th illustration is in the current book along with 10 others.
Two heating systems have come to my attention recently.
Mini split heat pumps selling for 600 to 1200 dollars. Heat pumps usually are used only
in warmer climates where the temperature seldom gets below about 30 degrees F because
they cannot extract much heat from colder air. However they might work in colder
climates if the evaporator, usually place outside was place in a crawl space or other space
protected from outside air and able to obtain some heat from the ground. Your crawl
space would have to be insulated (perhaps with styrofoam over the perimeter foundation
blocks on the outside and sealed against outside air (closed up - caulked and
weatherstripped openings and vents).
An unheated basement thermally separated from the main floor might also work -
drawing heat from the basement walls and floors as the evaporator works (in effect
cooling down your basement as it exracts heat for the heated main floor).
Another option for evaporator placement - a large solar heated greenhouse on the south
side of your house with insulating shutters closed at night - the floor of the greenhouse
and solar heat stored in thermal mass in your greenhouse would serve as the heat source
to the evaporator.
The usual cold climate heat pump uses underground water pipes or well water as a source
of ground (geothermal) heat to the heat pump. They cost $3,000 or more plus installation.
A mini split system might not heat a large house or poorly insulated house except in mild
weather. Smaller units provide 9,000 to 12,000 Btu per hour of heat. However some units
can spit out 24,000 oto 36,000 Btu of energy per hour which would be enough for most
of the heating season. However (again) these larger units may overburden the capacity of
the crawl space floor to 'wick up' heat from the ground. I just don't know. This idea - of a
crawl space installed evaporator is an idea only (which I am trying in my own home) that
might not work. But in theory it should.
A study of the concept was done by a national laboratory (I don't know which one off the
top of my head -Argonne I think) and a google search typing in 'crawl space heat pump'
should turn it up. The study as I recall concluded that heat was being extracted from the
crawl space walls and floor by the crawl space installed heat pump
Rocket stoves - here I mean rocket stoves of more high tech design than the stoves of
Ianto Evans, and the Cob Cottage Company. Richard Hill of the University of Maine
developed these in the late 1970s and a few were built and sold by a company called
Jetstream and some immitators Look online for details.
The Hill stove used a blower to provide air to the combustion chamber and a 'water
jacket' around the upper half of the wood fuel supply chamber to keep the upper half of
the wood from combusting, and thus control the speed of combustion going on in the
lower half of the chamber - thus providing an even amount of fuel flow and heat - in
effect a carburetor for a wood burning stove. This stove works at high efficiency with
almost no pollution or creosote build up - but is high tech and therefore could be
expensive and difficult to build (unlike the Evans rocket stove).
Cheap and simple solar house
Cheap and simple solar house:
One method to create a cheap and simple solar house suitable for living Zero Cost, as
described in detail in my new book to come out in 2010 is to build (essentially) two- 2 car
garages next to each other - with modifications to make the resulting structure energy
efficient to the point that the heating bill would be ZERO.
Modify the house to incorporate a hydroponic solar greenhouse for food production to eat
and/or sell. Two hundred square feet of greenhouse might provide 2,000 pounds of
produce (at 10 pounds per square foot) worth $2,000 to $4,000 dollars or more per year.
Your food requirements, property taxes (if you build in the right, low tax location and
build a practical no frills house), and some other costs could be met by the income from
As described in my book and elsewhere in this web site, it is possible for one person to
eat well for a few hundred dollars a year.
Additional improvements to the house could reduce or eliminate other expenses such as
the pesky and numerous 'miscellaneous costs' (as I call them) such as furniture, clothing,
media, household, kitchen, bath, yard, and recreation costs.
So you may be able to approach Zero Cost Living by building your house in a suitable
location and in the proper way.
You will still have some expenses and so may require a business, job (god forbid),
investments, etc. But they can be modest.
Cheapest food ever
Cheapest food ever
Recently I have discovered what may be the cheapest food ever.
I suspect the Native Americans, Hispanics, and the poor of the southern United States
have know this for a long time.
Eating primarily corn bought by the bushel, I estimate you may be able to eat for about
$44 a year.
Corn bought by the bushel could be home processed into an array of products by
preparing and grinding it to make various products including corn bread, hominy,
porridge, jonnycake,tortillas,pancakes, fritters, hush puppies,muffins,biscuits,cornsticks,
etc. etc. etc.
Corm meal and 'masa harina' (used to make tortillas) can be made from field corn, rather
than Sweet corn. All of these products can be made using field corn - avoiding too much
sugar in the diet - corn can have a high 'glycemic index' or 'glycemic load' if too sweet.
A 50 pound bushel of field corn can be bought for about $4 if bought direct from the
farmer as of December 2009.
Isn't field corn intended for animal food. Indeed it is and very good food for animals it is.
And, in can be good for humans too - after processing for human consumption -
processes such as 'nixtamalization' where the corn is soaked in lime or culinary ash to
11 bushels of corn costing only $44 will feed one person for a year based on the energy
content of corn. As I determined in my book and on this web site (in the previous article)
a person needs about 4.4 million Btu of energy per year. one bushel of field corn contains
about 450,000 Btu so 11 bushels contains 4.5 million Btu of energy.
The book 'The Cornbread Gospels' by Crescent Dragonwagon' goes into details on corn
Of course, eating primarily corn would not be healthy. Best would be to eat it with beans
and various whole grains and whole grain (brown) rice.
Rice has this problem: it can be hight glycemic and so promote diabetes.
Whole grains may have this problem: many folks, perhaps as much as 30 peercent of the
population may be gluten sensitive. Therefore, I believe it is better to stick to beans and
corn as the core of a minimal cost healthy diet. This was the core diet of the Native
CORN, BEANS,GRAINS, RICE - these are the high energy content plant foods that
sustain the poor people of the world. All other are not high in energy content and are
important and vital for health but you would starve if your diet consisted primarily of
these foods - without one of the '4 sisters'. Nuts, salads, tomatoes, berries, fruits, etc. are
not practical as a core basic food for us poor folks (or really cheap when you calculate
their energy content vs. cost).
(The potato to a lesser extent may serve as a 5th sister - as I am reminded by Van Gogh's
painting of 'the potato eaters).
-These other foods are great, healthy and valuable to suppliment your diet - especially
when you can get them in season cheap or free if you forage (such as for wild apples for
example in my region). But the 'four sisters' above are the queens of the human diet.
Meat? It is for the wealthy and foolish. It will make you sick over time if you eat much of
it - heart disease from fat and cholesteral. Wild meat is healthier and leaner and much
better for you. Even 'free range' fed cattle are better with good amounts of omega 3 fatty
acid - not found in feedlot fed cattle.
Meat is expensive when energy content vs. cost is calculated. If you can get it 'free' by
hunting (with efficiency - not by spending vast amoints of $ and time at it) it may be
One final concern about corn. It contains primarily omega 6 fatty acids and to get the
omega 3 you need, (in equal amounts to omega 6) you need to eat flaxseed or fish oil
which are rich in omega 3. I mix ground flaxseed into many of the foods I eat.
my new heat pump -personal experience
my new heat pump -personal experience
I installed a split mini heat pump a month ago (October 2009) putting the 'outside' unit in
my crawl space where it can pick up heat from the ground through the crawl space floor.
It is a 12,000 - Btu per hour unit theoretically able to provide 288,000 Btu of energy per
day - enough to heat my house in all but the coldest weather. The heat pump can provide
3.5 times as much energy as it uses. so for 3,400 Btu of electricity (1 kWh) I get 12,000
Btu or 8,600 'free' Btu of energy per hour.
It cost $700 to purchase on the web and I spent $90 for 3/4 hour of work by a pro to test
and release the r410A fluid.
It is a little noisier than I like but still not annoying and I am insulating the crawl space
ceiling to reduce compressor noise from the crawl space. If I did it again I might buy a
unit with a 'rotary' compressor which would cost a little more but be quieter. I can hear
the piston type compressor a little as it runs.
Also I need to build a plenum in the hall ceiling to suck cold air from the floor level of
my house (through the space between my studs and drywall) up to the air intake at the top
of the 'inside' unit of the heat pump. Now the heat output comes from below the unit, not
far from where the air input is on the top of the unit. Consequently the machines turns on
for a few minutes, then off again for a couple minutes, then on - all day. These changes
should let the system run longer on and stay off longer - not 'cycling' so often.
So far I am getting plenty of heat in Late November from this unit - drawing on 55 degree
crawl sapce air rather than cold 30 degree at night outside air which would make the
system operate with less efficiency.
I have learned that conventional heat pump systems for cold climates using water pumps
and pipes in the ground can cost around $20,000 - so the saving for the split mini air-to
air system $790 total (with me doing all the work but the final vacuum pumping, testing
and fluid release) is huge!
More on this later.
Update. March 2010:
Having used the heat pump through one winter I can say it worked well, saving me
money, time, effort and energy.
I burned only 26 bushels of corn, using the corn stove for 3 weeks in January and 3
weeks in February - and the heat pump for the rest of the season. Last year burning corn
only I used 86 bushels of corn. (My first year of burning corn I used 110 bushels but with
better window and attic door insulation and weatherstripping I have been able to cut corn
use). I miss a little (but not much) the exercise of moving and sifting so many bushels. I
don't miss all the cleaning sessions required - three per season - to keep the corn stove
operating. (I still must do one cleaning per season.) I used the corn stove only when the
outside temperature was very cold and I thought the heat pump might not keep up with
the heating demands and heat loss of the house.
Every day that I use the heat pump I use more electricity that the corn stove requires,
BUT NO CORN so I realize a savings per day of about $1 - and none of the work the
corn stove requires.
Here are the numbers:
Average corn use: 2/3 bushel a day or 2/3 x $4 = $2.67 Electric used by corn stove about
12 kWh per day.
Heat Pump electricty use: about 26 kWh per day or 14 more than the corn stove x 12
cents per kWh = $1.68 a savings of 99 cents per day.
Over an entire heating season the heat pump will save the the cost (and trouble) of buying
and handling 60 bushels of corn costing $4 x 60 = $240. The heat pump - running less as
on warmer days will use about $140 more electricity
(1,200 Kwh) than the corn stove requires. Savings = $100 per year.
Adding homemade solar energy systems could cut or eliminate heat pump or corn stove
use on sunny days. 300 or 400 square feet of solar collectors with heat storage might cut
corn stove/ heat pump use in half.
I expect to build this system using soup cans (painted black), black TV dinner trays, scrap
lumber, a few small fans (bought new) such as bathroom ventialtion fans costing $15
each, scraps of vinyl siding, recycled window glass, and possibly 4 or 6 mill clear plastic
costing a few cents per square foot.
So I getting closer and closer to zero cost heating.
I have considered a metal box type wood burning stove on my main floor, and even begin
building a rocket stove in my crawl space. There are plenty of sources of free wood
around, dead ash and elms, pallets, etc. However I am worried about the of the fire safety
of wood burning systems, especially where the flue pipes pass through ceilings, walls or
roofs. Heat pump and corn stoves seem to me to be very safe. (A corn stove burns at a
very low temperature compared to a wood stove - 600 vs. 1500 degrees. The flue pipe of
a corn stove just is't all that hot by the time the smoke passes through the heat exchanger
- in fact there is usually very little smoke).
Then there is the issue of frequent attention required to keep the wood burner going,
cutting wood, carrying wood, etc.
The corn stove may run for a week almost without attention except to remove the clinker
every 12 hours (a 2 minute job) and add 1 and 1/3 bushels of corn every other day.
A masonry fireplace heating system with heat absorbing thermal mass might be ideal for
true zero cost heat, requiring only one hot burn for an hour or two a day to stores heat for
24 hours. But this type of system can cost at least $10,000 and requires a skilled mason
which I am not. The thick mass of fireplace and chimney would - I think assure the safety
of the system.
A rocket stove may be thought of as a kind of poor mans' masonry fireplace. The
homemade system I have begun in my crawl space is an experiment only and I worry I
will burn down my house with it so I may never complete it. If i do I will report on it on
this web site.