The DIY Passive Solar Window Heater
The Do It Yourself Passive Solar Window Heater
How To Make A Passive Solar Heater.
This is a very simple and inexpensive project. There are many passive solar heating projects out there, but we must admit, we were very sceptical at first. In the cold November mornings, what help can a simple bit of styrofoam and aluminum foil really provide?
So we decided to make one and see how well it works. This is a very simple project using a couple pieces of styrofoam and some normal kitchen aluminum foil. And a can of black spray paint. The idea was also not to block out the window fully, so the heater was made a bit smaller than the window. This allows a little bit of a view and allows some sunlight to enter the room. If you want, you can fill the window completely with the foam and have even better performance.
How this works: When the sun shines, the black painted area will absorb the heat from the suns rays. Hot air expands and rises. The hot air will leave out the top vent in the heater. This will cause a vacuum and pull cooler air into the heater though the bottom vent. The cooler air will be warmed and the cycle continues as long as the sun is shining.
In the photos above you can see the homemade passive solar window heater.
First choose a south facing window and measure the window frame and decide if you want to cover the window completely or not with your solar heater. If you decide to completely cover the window, you have the added benefit of insulation at night to prevent heat loss. You can also use cardboard or anything else to make this heater if you are not going to insulate the window. Any rigid material that will hold its shape when placed into the window frame will work.
Cover the backing with aluminum foil on one side. Completely cover it and tape it down securely all over. Now simply cut vent holes in the top and at the bottom of your solar heater to allow air to flow freely. The size and position do not need to be exact. Larger openings will allow more air flow. Just make one at the top edge and another at the bottom edge. Tape off the edges of your aluminum foil to keep it secure.
Take the whole thing outside on a warm day and spray paint it all black. It is best to use a high heat paint that will hold up better to the heat of the suns rays. But a cheap can of black paint should work well because this heater will not be closed up. The metal shouldnt get as hot as an enclosed solar heater will.
Place your new homemade passive solar heater into the window that you measured it for and feel the heat. On a sunny day you will actually get a hot flow of air coming out of the top of the solar heater.
By taping a piece of plastic across the top opening of your heater, you can also prevent air flow in the reverse direction and further prevent heat loss when the sun is down. To do this, take a light weight piece of plastic, such as from a shopping bag and tape it on the top only. Leave it hanging freely down over the opening on the top of your heater. This will allow heat to pass through during the sunny hours but block the reverse flow of heat back out during the night.
It is amazing how much heat your new diy passive solar heater will provide. Try it and see for yourself.
Pros and cons of this design.
The positive things are its inexpensive design and cheap materials. Since this is indoors, you can use literally any material to make this heater. It will not be subjected to the elements so it can be made of cardboard. It can also be used to insulate your window and prevent heat loss if styrofoam is used and if the heater is fit tightly into the frame or taped around the sides. And since this is placed inside a window, there is no need for messy holes cut into the side of your home or camper. This is a passive solar heater, so there are no moving parts and literally no maintenance involved.
The only negative point is that you will be sacrificing a window for the heater.
Below is a video showing how to make a passive solar window heater yourself
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