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re: mobile home heating
28 jan 1998
dogsnus wrote:
>dion hollenbeck wrote:
>> ok, i have been following this thread for the past week now and i am
>> very puzzled. why should a wood heater be any more dangerous to fire
>> or death by asphyxiation in a mobile than in a regular frame home?
i'm puzzled too. why should a mobile home need any heater (often), since
it's so easy to place it with the long axis east-west and add on a plastic
film sunspace for solar heating? compared to million dollar homeowners, it
seems to me that most mobile home owners might have more appreciation for
some extra floor space and some heating energy savings and less in the way
of fixed ideas about what a home should look like.
>i've got one of the newer, better ones; and they are built,
>much better and fire resistant that the older styles.
i guess it has at least 3 1/2" of insulation. suppose it's 60' long
and 12' wide and 10' tall, and 5% of the floorspace is r2 windows, with
a thermal conductance of about 2160ft^2/r13 = 166 btu/h-f for the walls
and ceiling, and 36ft^2/r2 = 18 for the windows, a total of 184 btu/h-f,
so it needs about 24h(70f-30f)184 = 177k btu to stay warm on an average
december day where i live in pa, when an average of about 1000 btu/ft^2
of sun falls on a south wall.
suppose we enclose it in a half-greenhouse structure, using 24' long $35
curved galvanized pipes or $5 double 1x3 bows on 4' centers, covered with
a single $72 layer of 4-year greenhouse polyethylene film (which lasts a
lot longer if covered with shadecloth in the summertime) or clear
polycarbonate plastic, 24' wide x 60' long. it might look like this
from the east:
. ----
. . 4'
............ the north wall might have
. . . 4' | more insulation (leaves?)
............... covered with plastic film,
.. . ~18' or it might have 180
<-south . . . 55 gallon drums full of
. . .10' | water under the insulation
. . . to make this a kind of
. ............... envelope structure.
.......................................
8' 12'
....................
. . . 8' .
. . . .
. . . .
. . . . 12'
. . . .
. . . .
. . . .
. . ............
. . .
. . .
. . . 60'
. . .
. . .
. . .
. . .
. . .
. . .
. . .
. . .
. . .
. . .
....................
the south wall would collect about 18x60x0.9x1000 = 972k btu/day of heat,
of which 6h(80-30)24x60/r0.8 = 540k might be lost through the glazing,
leaving 972k-540k-177k = 255k btu/day for hot water and cloudy day heat
storage in a box full of water on the roof. the mobile home would need
about 5dx177k = 885k btu for 5 cloudy days in a row, which might come from
885k/(130f-90f) = 22k pounds or 12,000 gallons of water cooling from
130 to 90 f, eg a plywood box full of water 8' wide x 12' long x 4' deep,
lined with a single 20x20' piece of folded up epdm rubber roofing material,
with 2x4 exterior framing and fiberglass insulation. the water might be
warmed by some sort of passive solar collector in the sunspace, eg homemade
"big fins" attached to copper pipes, with a thermosyphoning warm water loop
to the box of water above, like this:
. .
. . . .
aluminum flashing ssbss . . 1/2" . .
.........................o... . copper . .
.........................l... . pipe . .
sstss . . . .
sssss might be a 1/2" x 1/16" . . . .
thick aluminum strip or angle --- . . .
.
| . <--foil-faced foamboard
. on the back side?
...then open it up like this: .
. . .
. . . . .
home depot sells dark- .ssbss . . . .
brown-painted aluminum ~5" ...o... . copper . .
roof flashing for $46.50 ...l... . pipe . .
for a 50'x2'x0.027" roll. .sstss . . . .
. . . . .
. . .
[use courier font.] .
| . this solar collector might be
. 60% efficient heating 120 f
--- . water inside an 80 f sunspace.
where i live, with an average of about 48" of rain per year, the 60x20'
roof could collect an average of about 100 gallons of water a day, which
might be stored in a pond in the sunspace and slowly pumped up to the box.
another part of the sunspace might have an artificial wetland for sewage
treatment, with condensation above that drips back into the rainwater pond.
nick
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