| Topic: |
Science > Physics |
| User: |
"" |
| Date: |
09 Feb 2006 12:49:55 PM |
| Object: |
Solar Ovens |
I'm reading about solar ovens today. They work by reflecting light
into a box with reflective sides, a black bottom, and a sealed glass
top. In nice days they can boil water, and cook food efficiently.
I have an idea I would like help thinking about. The idea is that I
could use solar ovens during the winter to heat my house.
If I set up solar ovens on the inside of my house, facing windows which
took in plenty of sun, they could catch the light comming through the
windows and heat up the oven. The heat in the oven could be used to
heat the house.
I'm not sure of the best way to take the heat from the ovens, and use
it to heat the air in the house. In order for the ovens to get hot,
you would have to keep the air in the ovens contained.
Also, I'm not sure if the ovens would get enough sun from the windows
considering they would be used in the winter, so maybe I should put
them outside and vent the air indoors. If I insulated the ovens, to
keep them warm during the winter, they might work out doors.
Can anyone help me think about this idea?
Thanks!!!
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| User: "" |
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| Title: Re: Solar Ovens |
10 Feb 2006 01:52:55 PM |
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wrote:
I'm reading about solar ovens today. They work by reflecting light
into a box with reflective sides, a black bottom, and a sealed glass
top. In nice days they can boil water, and cook food efficiently.
I have an idea I would like help thinking about. The idea is that I
could use solar ovens during the winter to heat my house.
If I set up solar ovens on the inside of my house, facing windows which
took in plenty of sun, they could catch the light comming through the
windows and heat up the oven. The heat in the oven could be used to
heat the house.
I'm not sure of the best way to take the heat from the ovens, and use
it to heat the air in the house. In order for the ovens to get hot,
you would have to keep the air in the ovens contained.
Also, I'm not sure if the ovens would get enough sun from the windows
considering they would be used in the winter, so maybe I should put
them outside and vent the air indoors. If I insulated the ovens, to
keep them warm during the winter, they might work out doors.
Can anyone help me think about this idea?
Thanks!!!
Just so you know, the "solar oven" idea simply takes a given area
(about 1/2 a square meter to about a square meter) and focuses the
sun's energy (about 1000 W/sq. meter) on a *smaller area* to increase
the temperature (but *only* to this *smaller area*, the focal point).
If you do this on the inside of your house, you'll only notice the
increased temperature as you get closer to your "pot". Total energy
input is the same as if you've never built the solar oven: 1,000
W/m^2.
Now, if you *surrounded* your *house* with mirrors and focused the
sun's rays on your house, now that's a different story... :)
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| User: "" |
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| Title: Re: Solar Ovens |
10 Feb 2006 02:08:58 PM |
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That's not entirely true. Some material is better at absorbing light
and turning it into heat than other material. If you make a solar oven
and paint the bottom black instead of white, the oven will create much
less heat. The same is true with my house. If I'm not using the light
to make heat, it gets wasted.
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| User: "Brian Whatcott" |
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| Title: Re: Solar Ovens |
10 Feb 2006 06:54:20 PM |
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On 10 Feb 2006 12:08:58 -0800, wrote:
That's not entirely true. Some material is better at absorbing light
and turning it into heat than other material. If you make a solar oven
and paint the bottom black instead of white, the oven will create much
less heat. The same is true with my house. If I'm not using the light
to make heat, it gets wasted.
Black surfaces in general absorb radiation better.
White surfaces reflect an appreciable fraction.
But if that light does not bounce back outside, it goes to make the
same amount of heating. It may not be obvious....
Brian Whatcott Altus OK
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| User: "YouGoFirst" |
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| Title: Re: Solar Ovens |
09 Feb 2006 02:28:48 PM |
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I have an idea I would like help thinking about. The idea is that I
could use solar ovens during the winter to heat my house.
If I set up solar ovens on the inside of my house, facing windows which
took in plenty of sun, they could catch the light comming through the
windows and heat up the oven. The heat in the oven could be used to
heat the house.
Like Timo said, your house is already a solar oven. If you want the sun to
heat your house more efficiently, you could always put in black flooring in
the areas where the sun comes in. That would help to heat up those rooms.
Another thing you could do is to put in some windows that have a high R
value. You could also install more insulation/better insulation (high R
value) and that way your house wouldn't lose much heat during the day. I
would also suggest growing some large trees on the south side of your home
(assuming you are in the northern hemisphere) so that during the summer you
don't have as much sunlight heating up your house.
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| User: "New Directions In Building Services \Australia" |
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| Title: Re: Solar Ovens |
09 Feb 2006 03:54:23 PM |
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"YouGoFirst" <yougofirst@hotmail.com> wrote in message
news:4CNGf.365187$qk4.140505@bgtnsc05-news.ops.worldnet.att.net...
I have an idea I would like help thinking about. The idea is that I
could use solar ovens during the winter to heat my house.
If I set up solar ovens on the inside of my house, facing windows which
took in plenty of sun, they could catch the light comming through the
windows and heat up the oven. The heat in the oven could be used to
heat the house.
Like Timo said, your house is already a solar oven. If you want the sun
to heat your house more efficiently, you could always put in black
flooring in the areas where the sun comes in. That would help to heat up
those rooms. Another thing you could do is to put in some windows that
have a high R value. You could also install more insulation/better
insulation (high R value) and that way your house wouldn't lose much heat
during the day. I would also suggest growing some large trees on the
south side of your home (assuming you are in the northern hemisphere) so
that during the summer you don't have as much sunlight heating up your
house.
Assuming deciduous trees
If you really want to get into it - borrow, hire, etc. a thermographic
camera and identify where heat/cool's coming in and going out - fix-up
whatever you can and get out the thermographic camera once again - repeat
seasonally until your totally satisfied (If your in Australia, you can pay
us to do it).
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| User: "" |
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| Title: Re: Solar Ovens |
09 Feb 2006 04:36:12 PM |
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Or, I could build one of these into my house:
http://solarcooking.org/wallovn1.htm
(It is a solar oven built into the side of a house)
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| User: "" |
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| Title: Re: Solar Ovens |
09 Feb 2006 03:23:32 PM |
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I just built a solar heater in one of my south facing windows. I used
3 tall mirrors, and placed on of them at an angle with the window and
the two others along the sides of the windows. I then covored up all
the holes with aluminum foil, and put a black piece of metal along the
floor of the heater. I put a tiny fan in the heater to blow the hot
air into the rest of the house, and covored the whole thing in a sheet
for looks.The sun is starting to set now, and it isn't very hot, but
during the day it was cooking in the heater.
What makes you think this isn't going to help heat my house? When the
sun shines in through the windows it mostly just lights the house, and
the heat gets lost. With this system the light gets trapped in the
mirror box, and converted to heat. It then gets used to heat the house.
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| User: "Greg Neill" |
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| Title: Re: Solar Ovens |
09 Feb 2006 03:28:57 PM |
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<learningmagic@gmail.com> wrote in message
news:1139520212.365749.93790@g47g2000cwa.googlegroups.com...
I just built a solar heater in one of my south facing windows. I used
3 tall mirrors, and placed on of them at an angle with the window and
the two others along the sides of the windows. I then covored up all
the holes with aluminum foil, and put a black piece of metal along the
floor of the heater. I put a tiny fan in the heater to blow the hot
air into the rest of the house, and covored the whole thing in a sheet
for looks.The sun is starting to set now, and it isn't very hot, but
during the day it was cooking in the heater.
What makes you think this isn't going to help heat my house? When the
sun shines in through the windows it mostly just lights the house, and
the heat gets lost. With this system the light gets trapped in the
mirror box, and converted to heat. It then gets used to heat the house.
What heat is coming from the solar heater that hadn't
already entered the house?
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| User: "" |
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| Title: Re: Solar Ovens |
09 Feb 2006 03:55:55 PM |
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What heat is coming from the solar heater that hadn't
already entered the house?
All of the sun light that the mirror box converts to heat, that would
otherwise just illuminate the house and eventually escape and get lost
without heating the house at all.
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| User: "Greg Neill" |
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| Title: Re: Solar Ovens |
09 Feb 2006 04:02:07 PM |
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<learningmagic@gmail.com> wrote in message
news:1139522155.569773.324120@f14g2000cwb.googlegroups.com...
What heat is coming from the solar heater that hadn't
already entered the house?
All of the sun light that the mirror box converts to heat, that would
otherwise just illuminate the house and eventually escape and get lost
without heating the house at all.
How would it escape? Some small amount would
reflect back out the window, but the same is
true (perhaps more so) for your solar box, no?
When light illuminates common surfaces (rather than
perfect mirrors), it is partially reflected and
partially absorbed. The absorbed portion is
degraded to heat.
It seems to me that concentrating the heat in the
solar oven only serves to create on spot that's
significantly higher in temperature at the expense
of other areas in the room.
Of course, you could then use this concentration
of heat to move it to remote areas (ducted fans,
for example).
Perhaps you should consider building your solar oven
outside, and ducting warm air in. That way you'll
be bringing in energy that would not have otherwise
entered the house.
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| User: "" |
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| Title: Re: Solar Ovens |
09 Feb 2006 04:22:06 PM |
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Perhaps you should consider building your solar oven
outside, and ducting warm air in. That way you'll
be bringing in energy that would not have otherwise
entered the house.
That was my origonal idea, but the work involved in creating that
system is more than I have time and energy for right now. What I am
doing inside is an expiriment, so I'll get back to you on how well it
works tomorrow when the sun comes back out.
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| User: "Greg Neill" |
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| Title: Re: Solar Ovens |
09 Feb 2006 04:34:24 PM |
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<learningmagic@gmail.com> wrote in message
news:1139523726.108187.103340@f14g2000cwb.googlegroups.com...
Perhaps you should consider building your solar oven
outside, and ducting warm air in. That way you'll
be bringing in energy that would not have otherwise
entered the house.
That was my origonal idea, but the work involved in creating that
system is more than I have time and energy for right now. What I am
doing inside is an expiriment, so I'll get back to you on how well it
works tomorrow when the sun comes back out.
You'll probably want to measure the room's temperature
with and without the set-up. Shut off heating to the
room and keep the door closed to minimize heat sharing
with the rest of the house. You might also put a fan
in the room to mix the air.
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| User: "Spaceman" |
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| Title: Re: Solar Ovens |
09 Feb 2006 04:08:37 PM |
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<learningmagic@gmail.com> wrote in message
news:1139522155.569773.324120@f14g2000cwb.googlegroups.com...
| >What heat is coming from the solar heater that hadn't
| >already entered the house?
|
| All of the sun light that the mirror box converts to heat, that would
| otherwise just illuminate the house and eventually escape and get lost
| without heating the house at all.
I think what you would really want to do is
convert an entire wall (sun side of course)
to be the "solar oven" for best results.
:)
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| User: "" |
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| Title: Re: Solar Ovens |
09 Feb 2006 04:18:08 PM |
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I think what you would really want to do is
convert an entire wall (sun side of course)
to be the "solar oven" for best results.
:)
I wish I could do that, but I don't have the materials, and already
have a house with a good wall I don't want to tear down. Spaceman, do
you have any ideas I could use to improve what I am doing already?
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| User: "Spaceman" |
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| Title: Re: Solar Ovens |
09 Feb 2006 04:49:56 PM |
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<learningmagic@gmail.com> wrote in message
news:1139523487.974771.87470@f14g2000cwb.googlegroups.com...
| >I think what you would really want to do is
| >convert an entire wall (sun side of course)
| >to be the "solar oven" for best results.
| >:)
|
| I wish I could do that, but I don't have the materials, and already
| have a house with a good wall I don't want to tear down. Spaceman, do
| you have any ideas I could use to improve what I am doing already?
Not really
Besides gathering more light to enter the window.
(ugly mirrors outside that only work part time unless
you actually get them to move automatically with the sun)
and maybe,..
You also have the option of building upon the wall with cheap
materials that would still get some of the job done.
It is all a matter of money though sadly.
:(
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| User: "PD" |
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| Title: Re: Solar Ovens |
10 Feb 2006 10:16:39 AM |
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wrote:
What heat is coming from the solar heater that hadn't
already entered the house?
All of the sun light that the mirror box converts to heat, that would
otherwise just illuminate the house and eventually escape and get lost
without heating the house at all.
To *some* extent that's true, but the loss is small. This is the reason
why glass greenhouses work, and you'll note that the inside of the
greenhouse doesn't have to be painted all black for the warming to
occur. The reason for this is that light entering into a greenhouse is
generally downshifted on reflection to be more toward the IR, which
glass is more impervious to. So the light comes in, but it can't escape
through the same route.
Now in your device, the light is trapped and converted and confined to
a small volume, whereas in the house the *same* light is dispersed
through a larger volume. Since the heat is confined to a smaller volume
in the device, it gets *locally* warmer than the surroundings. But if
the device weren't there, the same amount of heat would get deposited,
just in a more distributed way, and so you wouldn't notice a local
temperature increase.
PD
PD
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| User: "" |
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| Title: Re: Solar Ovens |
10 Feb 2006 01:43:49 PM |
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I uploaded some photos of my solar heater to Image Shack.
Outside Reflectors:
http://img270.imageshack.us/img270/8789/solarheater22pn.gif
The Box Inside:
http://img492.imageshack.us/img492/2204/solarheater27bo.gif
I put 3 big reflectors outside of the window, and inside have two
mirrors that direct the light to a tall piece of black metal. The
black metal gets really warm, and heats up the air in the box, which
then escapes out the top of the heater.
The air inside the box is much warmer than the air in the rest of the
room, and I don't feel this is only because the heat is getting
concentrated.
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| User: "Greg Neill" |
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| Title: Re: Solar Ovens |
10 Feb 2006 02:16:25 PM |
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<learningmagic@gmail.com> wrote in message
news:1139600629.555482.128730@g14g2000cwa.googlegroups.com...
I uploaded some photos of my solar heater to Image Shack.
Outside Reflectors:
http://img270.imageshack.us/img270/8789/solarheater22pn.gif
The Box Inside:
http://img492.imageshack.us/img492/2204/solarheater27bo.gif
I put 3 big reflectors outside of the window, and inside have two
mirrors that direct the light to a tall piece of black metal. The
black metal gets really warm, and heats up the air in the box, which
then escapes out the top of the heater.
The air inside the box is much warmer than the air in the rest of the
room, and I don't feel this is only because the heat is getting
concentrated.
Can you think of another explanation then?
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| User: "" |
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| Title: Re: Solar Ovens |
10 Feb 2006 03:31:15 PM |
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Yes. It converts sunlight into usable heat, instead of just
illuminating the room and reflecting the light back outside. The
reflectors bring more light inside, so you get more heat that way as
well. If I were to have the interior of the heater painted white, it
wouldn't generate heat, but because I use black metal the light gets
converted to heat and warms the house more than it would if reflected
off of my white walls and carpets.
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| User: "Spaceman" |
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| Title: Re: Solar Ovens |
10 Feb 2006 03:33:24 PM |
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<learningmagic@gmail.com> wrote in message
news:1139607075.247496.261040@f14g2000cwb.googlegroups.com...
| Yes. It converts sunlight into usable heat, instead of just
| illuminating the room and reflecting the light back outside. The
| reflectors bring more light inside, so you get more heat that way as
| well. If I were to have the interior of the heater painted white, it
| wouldn't generate heat, but because I use black metal the light gets
| converted to heat and warms the house more than it would if reflected
| off of my white walls and carpets.
It is simply storing heat that would not usually be stored
:)
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| User: "tadchem" |
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| Title: Re: Solar Ovens |
09 Feb 2006 05:18:11 PM |
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Apparently you just haven't gotten it yet.
If you want to *heat* your house during the winter with soalr energy,
you are going to *ahve* to get more sunlight into your house that it
would normally get.
The solar oven you linked to that is built into the side of the house
catches sunlight that is *outside* the house and stores it in the
cookpots. Then when the oven is opened from the inside of the house
and *especially* when the pots are brought inside, the added heat comes
with them.
You may want to try building an *anti-awning* outside a south-facing
window:
(1) Cover a board with reflective material. [cardboard and aluminum
foil will work to prove the principle]
(2) mount the board outside the house with one edge *beneath* the
window
(3) prop the board so that it reflects as much sunlight from the winter
midday into the window [the board should be about as big as the window]
(4) leave the window shades open all day
If you do this right, the *extra* sunlight coming in through a single
window will make the room almost unbearably hot, and with the help of a
simple fan to circulate the heat could heat a three-bedroom house.
It worked for me a few years ago in Brighton Colorado all winter!
Tom Davidson
Richmond, VA
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| User: "" |
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| Title: Re: Solar Ovens |
09 Feb 2006 05:44:15 PM |
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Apparently you just haven't gotten it yet.
If you want to *heat* your house during the winter with soalr energy,
you are going to *ahve* to get more sunlight into your house that it
would normally get.
The solar oven you linked to that is built into the side of the house
catches sunlight that is *outside* the house and stores it in the
cookpots. Then when the oven is opened from the inside of the house
and *especially* when the pots are brought inside, the added heat comes
with them.
You may want to try building an *anti-awning* outside a south-facing
window:
(1) Cover a board with reflective material. [cardboard and aluminum
foil will work to prove the principle]
(2) mount the board outside the house with one edge *beneath* the
window
(3) prop the board so that it reflects as much sunlight from the winter
midday into the window [the board should be about as big as the window]
(4) leave the window shades open all day
If you do this right, the *extra* sunlight coming in through a single
window will make the room almost unbearably hot, and with the help of a
simple fan to circulate the heat could heat a three-bedroom house.
What angle should I prop the board? I have a lot of extra sheet metal
which is way more reflective than aluminum foil I can use. Do I want
it to be at an upward angle to the window ( \.| ) or a downward angle (
_.| ).
Also do you think I could make some of these on the other sides of the
windows as well?
It worked for me a few years ago in Brighton Colorado all winter!
Tom Davidson
Richmond, VA
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| User: "tadchem" |
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| Title: Re: Solar Ovens |
10 Feb 2006 04:19:17 PM |
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wrote:
<snip>
You may want to try building an *anti-awning* outside a south-facing
window:
(1) Cover a board with reflective material. [cardboard and aluminum
foil will work to prove the principle]
(2) mount the board outside the house with one edge *beneath* the
window
(3) prop the board so that it reflects as much sunlight from the winter
midday into the window [the board should be about as big as the window]
(4) leave the window shades open all day
If you do this right, the *extra* sunlight coming in through a single
window will make the room almost unbearably hot, and with the help of a
simple fan to circulate the heat could heat a three-bedroom house.
What angle should I prop the board? I have a lot of extra sheet metal
which is way more reflective than aluminum foil I can use.
"(3) prop the board so that it reflects as much sunlight from the
winter
midday into the window [the board should be about as big as the
window]"
Do I want
it to be at an upward angle to the window ( \.| ) or a downward angle (
_.| ).
I suspect the midday sun in your location is probably *above* the
horizon year-round, so if you are mounting a reflector *beneath* the
window to reflect sunlight through the window, you should probably
angle it to reflect the suinlight *upward*.
The exact angle that will work best will depend on your latitude, the
compass orientation of your house, and any nearby obstacles to
sunlight.
Go outside at noon and adjust it.
Also do you think I could make some of these on the other sides of the
windows as well?
Suit yourself. I found that a single reflector did the job of keeping
the house comfortably warm. I once saw plans for a solar oven for
baking (bread, cookies, etc) that was basically a glass-fronted,
foil-lined box with three such reflectors around it. Properly angled
and faced towards the sun you could easily cook food with it. I don't
think you want *that* much heat, though.
Tom Davidson
Richmond, VA
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| User: "" |
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| Title: Re: Solar Ovens |
11 Feb 2006 11:25:07 AM |
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I have a specific question. My solar heater is tall enough a person
could stand inside, and just wide enough a person could squeze their
shoulders into it. It stretches up a window of the same size, that is
tall and faces the south side of my house.
Right now it is 12:25 and the temperature just above the solar heater,
where I have an opening in the top is 80 degrees farenheight.
Do you think that this heat is going to help warm up the house? When I
put my hand down into the heater it is even warmer. Should I find a
way to blow the air out of the heater, so it circulates into the house?
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| User: "tadchem" |
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| Title: Re: Solar Ovens |
11 Feb 2006 06:25:00 PM |
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wrote:
I have a specific question. My solar heater is tall enough a person
could stand inside, and just wide enough a person could squeze their
shoulders into it. It stretches up a window of the same size, that is
tall and faces the south side of my house.
There's your problem. You need to collect the sunlight from an area
LARGER than the window and let it in through the window.
You are trying to *HEAT* your house.
You are trying to GET the heat from sunlight.
You need to get MORE sunlight into your house than you normally would
for the heat to accumulate inside the house.
If you look at the design of the through-the-wall solar oven you linked
to earlier, the oven collects sunlight *outside* the souse that
normally would not enter the house, and brings it in.
Right now it is 12:25 and the temperature just above the solar heater,
where I have an opening in the top is 80 degrees farenheight.
Do you think that this heat is going to help warm up the house? When I
put my hand down into the heater it is even warmer. Should I find a
way to blow the air out of the heater, so it circulates into the house?
I am not sure how your solar heater is designed, but if you open the
bottom on the outdoor side to let cool air into the hteater, and then
open the top of the window to let the warm air into the house, then
convection should be enough to get the air to flow.
You still need to gather more sunlight than the window would *normally*
gather to get any heating benefit.
Tom Davidson
Richmond, VA
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| User: "Brian Whatcott" |
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| Title: Re: Solar Ovens |
11 Feb 2006 09:57:47 PM |
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On 11 Feb 2006 16:25:00 -0800, "tadchem" <tadchem@comcast.net> wrote:
learningmagic@gmail.com wrote:
I have a specific question. My solar heater is tall enough a person
could stand inside, and just wide enough a person could squeze their
shoulders into it. It stretches up a window of the same size, that is
tall and faces the south side of my house.
There's your problem. You need to collect the sunlight from an area
LARGER than the window and let it in through the window.
You are trying to *HEAT* your house.
You are trying to GET the heat from sunlight.
You need to get MORE sunlight into your house than you normally would
for the heat to accumulate inside the house.
If you look at the design of the through-the-wall solar oven you linked
to earlier, the oven collects sunlight *outside* the souse that
normally would not enter the house, and brings it in.
Right now it is 12:25 and the temperature just above the solar heater,
where I have an opening in the top is 80 degrees farenheight.
Do you think that this heat is going to help warm up the house? When I
put my hand down into the heater it is even warmer. Should I find a
way to blow the air out of the heater, so it circulates into the house?
I am not sure how your solar heater is designed, but if you open the
bottom on the outdoor side to let cool air into the hteater, and then
open the top of the window to let the warm air into the house, then
convection should be enough to get the air to flow.
You still need to gather more sunlight than the window would *normally*
gather to get any heating benefit.
Tom Davidson
Richmond, VA
OK here's a low, low cost solar heating method.
Assuming you have a pitched roof, you put a clothes dryer air exhaust
hose in the peak of the roof , with a little fan sucking this air into
the lower rooms.
Ideally, you control the fan with a little box that senses temperature
of 75+ in the roof peak, and temperature below 71 in the living room
before turning on.
That warm air assist from maybe 400 sq feet of solar heated roof
could provide an extra 10 kW of warm air.
Worth 50 cents per hour.
Say $20 / wk. Set against that a $50 set up cost for the blown air.
Brian Whatcott Altus OK
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| User: "tadchem" |
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| Title: Re: Solar Ovens |
12 Feb 2006 12:33:30 PM |
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$20/wk does NOT qualify as 'low cost' when a total investment of a few
dollars (aluminum foil, large used cardboard carton, tape) will heat
your home *all winter*.
Tom Davidson
Richmond, VA
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| User: "Brian Whatcott" |
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| Title: Re: Solar Ovens |
12 Feb 2006 02:35:35 PM |
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On 12 Feb 2006 10:33:30 -0800, "tadchem" <tadchem@comcast.net> wrote:
$20/wk does NOT qualify as 'low cost' when a total investment of a few
dollars (aluminum foil, large used cardboard carton, tape) will heat
your home *all winter*.
Tom Davidson
Richmond, VA
Now hang on a durn minute! I proposed $20/week SAVINGS at a putative
one-time cost of $50 Are you pushing trhe idea of carboard and foil
ovens inside the house still?
Brian Whatcott Altus OK
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| User: "N:dlzc D:aol T:com \dlzc\ N: dlzc1 D:cox" |
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| Title: Re: Solar Ovens |
12 Feb 2006 11:04:11 AM |
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Dear Brian Whatcott:
"Brian Whatcott" <betwys1@sbcglobal.net> wrote in message
news:rubtu1t8a3q6kusj5rvlo3lq9ufejq4vhb@4ax.com...
....
OK here's a low, low cost solar heating method.
Assuming you have a pitched roof, you put a
clothes dryer air exhaust hose in the peak of
the roof , with a little fan sucking this air into
the lower rooms.
Ideally, you control the fan with a little box
that senses temperature of 75+ in the roof
peak, and temperature below 71 in the living
room before turning on.
That warm air assist from maybe 400 sq feet
of solar heated roof could provide an extra
10 kW of warm air.
The problem is, where heating energy costs are high, the
under-the-roof temperature never gets above 45 deg even with the
Sun out. And this intermediate temperature, if harvested, puts
colder air adjacent to the (apparently) poorly insulated ceiling,
providing a net heat loss.
The best solution is to move where it is not that cold in the
winter. But somewhere there is water.
David A. Smith
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| User: "Brian Whatcott" |
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| Title: Re: Solar Ovens |
12 Feb 2006 02:33:14 PM |
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On Sun, 12 Feb 2006 10:04:11 -0700, "N:dlzc D:aol T:com \(dlzc\)" <N:
dlzc1 D:cox T:net@nospam.com> wrote:
Dear Brian Whatcott:
"Brian Whatcott" <betwys1@sbcglobal.net> wrote in message
news:rubtu1t8a3q6kusj5rvlo3lq9ufejq4vhb@4ax.com...
...
OK here's a low, low cost solar heating method.
Assuming you have a pitched roof, you put a
clothes dryer air exhaust hose in the peak of
the roof , with a little fan sucking this air into
the lower rooms.
Ideally, you control the fan with a little box
that senses temperature of 75+ in the roof
peak, and temperature below 71 in the living
room before turning on.
That warm air assist from maybe 400 sq feet
of solar heated roof could provide an extra
10 kW of warm air.
The problem is, where heating energy costs are high, the
under-the-roof temperature never gets above 45 deg even with the
Sun out.
///
David A. Smith
Well, I have done solar heating in a cool climate,
and done roof evaporative water cooling in a hot climate and I've
measured under roof peak temperatures - I found they can get quite
high.
Don't understand why you would never measure more than 45 degF in
Sunlight. I suppose that's equivalent to saying there are places
where the hottest day temperature is less than 40 degF.
That doesn't apply anywhere on Earth as far as I know?
700 watts per sq meter is appreciable - even when you only recover 35%
of it.
Brian Whatcott Altus OK
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