window mounted solar hot air furnace (aluminum soffit based) - twin wall polycarbonate sheet
Good evening, welcome to my "off-grid contest" entry.
I have shown you a product designed to reduce your winter heat and carbon footprint by using the power of the sun for free heating!
There are many projects using the sun to heat the space.
However, most of them are permanently installed flat-panel collectors made of soda cans or aluminum downpipes.
Installing a permanent collector usually means drilling two large holes on the side of your house to lay the pipes.
My Collector is installed outside the window and can be removed when the heating season is over.
The most intrusive part of the installation is to remove the flyscreen of the window.
In addition, the absorption plate based on aluminum soffit is much more efficient than the soda tank or the aluminum lower spray;
For a collector of a given size, you can harvest more heat.
The collector based on aluminum soffit is more expensive than the soda tank collector, but more expensive than the aluminum spray collector.
As an additional bonus, this collector does not require power, a fan or any form of forced air.
The current of the air through the collector is only driven by natural convection.
When the sun heats the air in the collector, it rises and escapes through the output vent.
Therefore, the cold air is sucked into the collector by entering the vent to replace the warm air.
The whole cycle continues without the need for fans.
I suggest you use better quality if you want to do this (more expensive)
I have drawn a chart for you other than this particular item, hopefully this is self-explanatory, but I will start with the intake of cold air. 1)
Breathe in from the cold air in the room from the air inlet at the bottom of the device.
From there, it travels indoors in the cold air until it reaches the chamber in front of the unit exposed to the sun's rays. 2)
In the room behind the polyester glass, the sun shines on the black aluminum sofa and heats it.
When cold air encounters soffit, it warms up when it rises through the perforation.
This rising air is constantly replaced by cold air that sucks in cold air. 3)
The warm air travels through the hot air chamber until it is released to the room through the hot ait outlet.
The collection unit can be hung on the windowsill with air intake and exhaust ports inside and the rest outside the house.
Windows must be single-hanging;
The position where the glass pane slides vertically to open and close the window.
The width of the collector is the same as the width of the window opening.
When the collector hangs on the windowsill, the window can be closed to the collector in order to "clamp" it in place.
After adding some wind and rain stripping to close the small gap, the installation is complete.
The exact size of this box doesn't matter because you have to customize this design to fit your own window.
If you are lucky enough to be able to use a south facing window close to the ground, then I can only say the bigger the better.
The reason is that you can support your collector with the ground and you don't have to worry about the weight.
You should also use thicker materials like 1/2 sheets instead of the 1/4 sheets I use.
But be careful that the collector installed near the ground increases the risk of occlusion.
You should do a solar site survey (link here)
Before building a collector
My Collector hangs on the window on the second floor.
No support below.
Therefore, I have to reduce the weight of it as much as possible.
I chose a shell of 1/4 OSB with very few support frames.
The only frame is a small wooden strip of 3/4x3/4, torn off the board of 1x6.
They are mounted anywhere along the corner where OSB meets two sheets of paper.
The two "L"-shaped sides of the collector are cut into pieces from OSB.
This is important.
If the collector's side is cut into two pieces, there is nothing to keep it in shape, and once you pick it up, it folds up like a book.
The whole thing was assembled with glue and 5/8 "brad nails on the 18 th.
Later, when installing foamboard insulation materials during construction, I nailed everything with a 1/2 Crown nail.
The insulating material used is 1 ''polystyrene.
Some of the people who are familiar with the solar collector reading this may think, "WTF is what he is doing and he should use poly-cyclo-uric acid salt! ".
I know I should use polyiso insulation because polystyrene tends to melt at high temperatures.
However, in search of polyiso, I searched the city for a few days and couldn't find it.
I have to settle for polystyrene, who knows, maybe it will work well.
The Foamboard is simple to install and requires only a knife and a tube of foamboard adhesive.
I tend to tell you that after you glue the board for the first time, you should pull the board off the wood and let it ventilate for five minutes before sticking it back.
However, a few years ago, when I insulated my basement with this kind of thing, I specifically didn't stick them on it after sticking a few panels, and they were as good as other panels.
After insulation, I sealed all the joints with the tuck tape to prevent ventilation.
The last picture shows a foamboard of 4'by 8.
I cut it around!
The partition divides the space in the device into two separate air flow channels.
It allows more cold air from the air inlet to enter the heating chamber down along the back of the unit.
It also allows warm air to spread upwards along the top of the unit and is discharged from the room without mixing with the cooler air.
The partition consists of 1/4 'osb with a gasket on each side.
The gasket is made by tearing the 1x6 board into a 1 1/2 "x 3/4" strip.
These strips are glued to the insulation with foamboard adhesive and then secured with a 2'16 specification Brad nail that pops in from the enclosure.
They run along both sides of the collector and stop 1 1/2 from the bottom.
Next, cut two OSB pieces to accommodate the spacers, then glue and nail in the appropriate position.
At the bottom of the collector, a space of 1/2 is set aside allowing cold air to enter the heating chamber.
Now we're talking about business.
Now let's talk about the real meat and potatoes of this whole thing.
The absorbing plate is a plate-
It's like absorbing the sun's light, getting hot, and passing heat to something that flows through its working medium.
In our case, the working medium is air, but it can also be water.
You can use several types of absorber, including solid soffit in the rear-end collector, soda tank, aluminum lower nozzle, ventilated soffit and aluminum window yarn.
I think ventilation soffit is the best option, because it is one of the most effective options in terms of the heat you get, it is easy to build and is cheaper than window screen and downspray.
Ventilated aluminum soffit is known as the hundreds of small hole marks for piercing.
It gets hot when the sun shines on the sofa.
The air is sucked through the perforation and heated during the process.
When you feel free heat on your skin as an occupant of your home, it will warm you and make you happy in the process.
Anyway, the first step in installing soffit is to make the gasket.
They run the entire length of the OSB partition, tilting from 1/2 at the bottom to 3 inch at the top.
I just took some boards of 1 by 6, cut it in length on the Mitter saw, tear it to 3 1/2, and then tear it to length with diagonal lines.
The resulting two parts should be close to the same, with a thickness of 1/2 on one end and 3 inch on the other.
Next, they glue in place with the foamboard adhesive and fix it with 2 inch 16-spec brad nails shot out of the outer film.
The first piece of soffit is cut into length and then a 3/4 lip is bent on the tail at the bottom.
The lips are made by clamping soffit onto my workbench and using the egde of the workbench as a guide as I use a hammer to move along the workpiece.
When installing the first piece of soffit, the lip covers the air gap between soffit and the booster divider.
Two other pieces of soffit were cut and installed.
They are assembled together as you install them on the House.
Each piece has a "tongue" with a "groove" on one edge ".
The groove of the first piece accepts the tongue of the second piece.
Three pieces were used in total.
The 10 feet yuan in hardware store is enough. .
Worth about $17.
After all the soffit was in place, a foamboard cover was made to fit the remaining space and bonded in place with the foamboard adhesive.
Cut a piece of 1/4 'osb into a suitable foam plastic cap with a 1/4 'on the bottom of the lid '.
Now, the absorbing plate has a 1/4 boundary on all four sides.
This is an important function of installing polycarbonate glass and Batten decoration.
Finally, paint the entire absorbing plate black with a few cans of paint.
I should have painted it with a high temperature BBQ, but I didn't find it.
The first thing I do is make a frame on the surface of the collector with 3/8x1/2 bars.
They are 3/8 thick, matched with the thickness of the double-wall polycarbonate glass windows, with a width of 1/2, which can cover the OSB side, while exposing 3/4 of the foamboard around.
It is well known that double glazing has good thermal insulation properties.
In order to keep the insulation between the foamboard and the glass window seamless, the glass window can only be placed on the foamboard all the time.
I cut the glass windows with a special "plastic board" cutting blade with a round saw.
It is 1/4 "1/4" smaller than the opening of the frame to allow expansion.
When cutting, to prevent burrs from forming, it is best to keep the plastic film on both sides.
Make sure you cut so that the cells are oriented vertically.
Only one side can face the light of the sun.
It is usually marked with a plastic film covering it.
After cutting, peel off the corner of the film on the UV-proof side, mark the panel with a masking tape, and peel off the rest of the film.
After cutting, pick up the blow gun from your air compressor and blow out all the dust in each unit of the film.
Then seal both ends with a dust belt (
Also called ventilation tape or ventilation tape).
Then, polycarbonate glass can be laid inside the frame and then fixed with Batten decoration.
Batten decoration is 1 1/4 'by 3/4 'strip torn from 1 by 6 boards.
It is cut to fit to be placed around polycarbonate glass in a frame with a midd angle.
The wooden glue and Brad nail fix the slats.
Finally, a circle of external caulking runs inside the batten decoration between the decoration and the glass window.
On the sunny evening the next day, when I got home from work, I decided to hold the collector in the sun to see how good it would be.
I am very satisfied with the initial results.
First, it was late at night, so the sun hung low in the sky far west.
As many low-lying clouds hang around the Sun, collectors rarely receive direct sunlight.
Most of the sunlight reaching the collector is filtered through the thin cloud part.
Also, it was difficult for me to avoid the shadows of the neighbor's cottage, and to avoid a nearby tree and telephone line pole.
Needless to say, the conditions are not ideal.
Nevertheless, things have succeeded.
Even without a fan, there is a considerable amount of warm air rising from the collector's exhaust opening.
However, I read that forced air significantly increased the production of these collectors, so as the sun quickly fell down, I rushed to take apart an old junk computer to take it out (very large)cooling fan.
I quickly made an OSB which is larger than the exhaust port of the collector and drilled a hole in it that is the same size as the fan.
With the OSB sheet above the exhaust opening and the fan passing through the collector and the top, I was surprised by the results.
For a short period of time thereafter, the collector was fully exposed to direct sunlight, and I must say that the heat was being released from that thing.
Feel as much as output (
In terms of temperature and flow rate)
As a forced air heater of 240 V, such as an electric heater installed in my home for space heating.
In other words, when it runs, I feel like my hand is right in front of one of the heaters.
It was overcast again before I took out the thermometer.
The output temperature dropped me a lot.
With the thermometer, I measured a stable 12oC at the air inlet and 20oC at the air outlet.
All have good airflow;
It is similar to the air outlet from the drying machine.
Sorry, I have no way to measure and quantify the airflow.
Therefore, I am also unable to calculate the power of the unit based on the speed at which the unit collects heat energy from the sun.
Still, I believe this collector will provide zero heat to keep the room warm in sunny, sunny winter.
Given that my material costs about $60, depending on the weather, it should pay about three times for itself during each heating season.
Once I have this thing installed on the window, I will see how it heats the room.
In fact, I expect it to perform better in December than it is now in September, as the sun is still tracking fairly high in the sky and at a fairly high angle to the vertical collector.
In December, the low-tracking sun would almost reach the collector directly, increasing the output.
Unfortunately after the dedline of this game, the sun shines on collectors and I will not be at home.
Once I get the results, I will update the issue with my results.
Before I Hang this thing outside my window for all my neighbors to see, I want it to look a bit more "finished" than the OSB box.
So I took a black mark and painted the color on all the parts that were going to be exposed.
Kidding, I used the paint but the paint work was terrible and you might think I was 2 years old and I did use the black mark.
The terrible thing is that from a distance of about 5 m it actually looks half decent.
When I build the window box collector Mk.
I will use good things. one-
The plywood and paint on the sides are really good.
I swear I will even wear a clear coat on it.
The bottom profile of my window is nothing more than adding a suitable size wood under the corner of the unit.
This strap transfers the weight of the unit to the windowsill instead of emphasizing the vinyl trim around the window frame.
The sealing flange is the wood ring around the unit in the second picture.
Round the outer surface of the flange around the foam ventilation sealing tape.
This should create a seal between the flange and the inside frame of the window.
Regarding the results of the second Test, I will be a little simpler.
I had the collector run with the fan for about an hour and check every five minutes or so.
This time it was much earlier than the previous test.
The sun is higher in the sky, and there are no shadows on nearby trees and poles to worry about.
In most tests, however, the sun barely passes through dense clouds.
The result is good.
The heat output remains stable at 29oC with the input of 17oC and the air current is quite strong.
I made a temporary streamer with a sales receipt and attached it to the fan trying to get people to see how much air this thing has.
It's really important for such a big fan.
I am also satisfied with the results of the second Test.
What it tells me is that I can still get a lot of heat available even on clear, cloudy days.
BythatI is a cloudy day without rain, fog or snow.
At some point, the collector does get direct sunlight for a few seconds.
The output temperature quickly rose to 35oC and then fell back quickly.