re: solar collector design for a solar closet?
19 nov 2002
>...i don't like the tubes embedded in the concrete floor...
you might insulate the basement and fill it with rocks. the floor above
could have a low r-value, or some controllable vents.
>i also do not like the stagnant air of a hydronic radiant heat system.
>they are also much more expensive compared to a forced air system.
>the control systems for hyrodnic that i have seen appear to be fairly
>complicated and computerized. i would prefer a very simple logic
>operated system using a couple of thermostats.
i've seen complicated hyrodnic floor systems with computerized boilers and
lots of zones, but it seems to me they can be simple and inexpensive, with
just one or two zones and no computers. they are great low-power water-air
heat exchangers with lots of thermal conductance and desirable thermal mass.
>no solar attics or solar roofs - the maintenance and potential for
>damage to the roof and interior damage are such that i would not build
>this type of system. snow, hail and tree limbs are enough of a menace
>to a stanard roof.
imagining larger menaces might help...
|judy slavin and her family practiced sailing from san diego to the caribbean
|and back, through the panama canal, twice, before their 5 year cruise around
|the world. in her last communication home, faxed from tonga, before hitting
|a 50 knot gale with 20' seas, she told friends
| this life is by no means stressless. at times i'm more stressed than i ever
| thought i was capable of enduring. you guys probably laugh at this, but
| just think of taking your home through a small pass in the coral with a
| strong current. once you start the approach, there is no turning around...
|their compass 47 cutter, a 30,000 pound, long-fin-keel, performance cruiser,
|was torn open by a freighter at 3 am on november 24 "as a vicious northeast
|gale roared through the rigging," 30 miles at sea, northeast of new zealand.
|"only the wife survived, washed ashore 40 hours later. when she was found,
|suffering from exposure and severe back injuries, she gave the exact
|coordinates of where their boat was plowed under by the ship that had come
|suddenly out of the black night. she was that kind of meticulous sailor."
>a solar space made from half a green house sounds maintainable to me.
it's easier to maintain if it's only 8' tall, eg a lean-to quarter cylinder.
>1 day heat storage - i don't know if that is the exact figure, but
>this is solar assisted house.
the first day may be the hardest, with a much higher required charging rate
than a rarely-discharged cloudy-day store.
>we have had wind chills of -85f and absolute lows of -45f. i am afraid
>of the solar space failing and turning the water wall into an iceberg :-)
you might seek professional help. or do calculations. how long will it
take for an 8' cube of water with r20 walls to freeze solid at -45 f?
plastic film drum liners on shelves might be freeze-tolerant.
>if i could store heat for (most?) of a night, i would be very happy.
>if the house did not fall below 60f at night and used the furnace for
>the morning warm up, that would be good. does efficiency of a solar
>closet improve if the heat stored in the day is used during the night
>so the solar closet (battery) starts from a relatively cool state in
sure, but doing the whole job may not be as hard as you think.
>it seems like if we place a vertical solar collector inside a solar
>space, that would increase the heat gain.
it would decrease the solar heat gain, but increase the temperature.
>without the solar space, the collector is loosing heat back into
>a 20f atmosphere. if the solar collector is in a solar space,
>it would only be loosing heat back into a 80f space. is this correct?
sure, altho i woulda said "losing."
>given the low tempatures here, that would seem prudent to put the
>solar collector inside a solar space. that should shrink the amount
>of glazing down considerably.
using an inexpensive sunspace as a "parasitic heater" can lower the heat
loss from a high-temp solar collector inside and shrink the number of
collectors needed. using the lower-temp air inside the sunspace to heat
a house on an average day can put you further ahead of the game. you
might call this "thermal cogeneration."
>a 4' x 4' x 10'tall solar closet is only 16 sq ft of floor space.
>even two or three (48 sq ft) of these does not seem excessive if it
>could provide much of the house's heat. 104 4" x 10' tubes of water
>in a 4x4ft room sounds ok. even two would be ok.
we might have a sunspace on the south wall of a walk-out basement, with
a room full of 4" water tubes or cylindrical vertical rock gabions made
from 2"x4" welded-wire fencing for overnight heat storage on an average
day, and a waterwall solar closet with its own glazing for cloudy-day
heat storage. the floor above could have vents, and we could release warm
air from the rock room or hot air from the closet as needed to keep the
upstairs living space warm. this might work without fans.