Cudos on the build. When I built one of these I only had one input port and forced the air to traverse the entire unit keeping it under the sun longer and achieving a higher temperature output. Of course as soon as you put a fan on it the length of time is shortened and the temperature will drop. Trying ti find the sweet spot of temperature and flow is the challenge. I perhaps would have either forgone the fan or put it on a speed control. The second idea was pure genius.
I wonder if just having the black aluminium perforated sheets suction cupped to the inside of the window would offer any heat... without the fans and boxes, and if so, would they cause more cold at night?
the black sheet is a black body absorbing solar radiation and would generate the same amount of heat whether it is sandwiched between two sheets of glass or on the inside as you suggested. and no they would not cause more cold at night.
@@rifhc TY for your reply, now I have one other question, if that sheet collects the same amount of heat with or with out being contained, would NOT having any black body, absorb the same amount of heat through the window into the room, pretty much back to where we started? And no I'm not being a smart @22 I really want to know.
@@dojodance When sunlight shines on an object (specifically long wavelengths, infrared), it causes the molecules to vibrate and thereby the object gives off heat. Heat is simply a byproduct. The object can reflect or absorb the radiation depending on material and colour. Remember light is simply radiation just like x-rays, but at different frequencies. If you want to try a simple experiment, go outside and stand in the sunlight with a white t-shirt on. Then try on a black t-shirt. You should be able to feel a difference in temperature between the two. If you don't have a black sheet of aluminum in front of the window, the light will be absorbed by various materials in the room. The objects will reflect and absorb the sunlight differently and consequently emit different amounts of heat. So by placing a black object that has good absorption properties in the direct sunlight we can try to maximize the heat generated. Does this answer your question?
Could we make the same system 1,5 M tall and use convection to have cold air entering the heater in the bottom and hot air going back in the room in the top ?
You could, but if the heat exchanger is working well, the forced air flow from the fans will improve the throughput of warm air going through the device. Also, probably the device is limited to a temperature delta/change so if the device is only capable of increasing the input vs output temp by ~25-39 degrees, you’ll have improved performance by using ‘preheated’ interior air as the input air vs much colder exterior air.
@@Stormsteed Thanks. My idea was actually to take air from the interior (so preheated) and put it back in the interior. But just to use convection and the fact that the hot air tend to be at the top. I think the througput of air doesn't matter much, if the air go slower it will be heated more, so same energy
@@wulfhart2653 I think you need at least one fan to move the air through to take advantage of the heat exchange effect of the box. Think about your hot attic in the summer. You may have open vents in the roof, but the removal of hot air from your attic is greatly improved if you install fan(s).
Putting it inside the window won't help at all because that heat is already inside the house as long as the curtains are open. It needs to go outside, somewhere where it's not blocking a window. Putting the perforated aluminum between the panes will increase losses. Put your hand in front of the exposed glass, and your other hand behind the aluminum and tell me which feels warmer. Also, you're not looking for the highest possible exhaust temps, but best thermal output, which is achieved by more airflow. Looks like good build quality though.
@@blurglide yeah I know what what you said and I'm telling you that it reads the way you did not intend so you should consider phrasing it more precisely instead of being snarky. Help is a very vague term in this context when the guy is trying to heat his home
@@TwoForFlinchin1 Help = make the room warmer than it would otherwise be without the device. This won't help to do that. It'll *work* in that you can put it in a sunbeam and it gets warm, but it won't *help* because that solar energy was already inside the house. If you put this in a glass box outside and blow house air through it, then it'll help. I'm not trying to be snarky. What is unclear?
Wouldn’t that also work with newer windows or one to put a piece of plexiglass over the recessed window box with pixie glass and an N put a hole in and out put a hole cut into a top and bottom respectively in the panel the middle of the aluminum panel in between the window in the way of the pixie glass over the recessed window pane area
Perhaps that is not what passive means in this case. The fan is on or off in this heater. In active heater there would be some thermostates, maybe timers and some other automation. That's what makes it "active".
@Mikowacomet Just a clarification. Active in my mind is the act of expending energy to generate heat. Like burning wood or conducting electricity through metal coils to produce heat. By placing a black body in direct sunlight to produce heat is passive. You are correct that the fans are not passive. When I was using the term passive, it was not meant to describe distributing the heat with the fans. The fans are definitely active. Sorry for the confusion.
A quick note to cut down on confusion. This is an active solar heater. Passive solar doesn't rely on any mechanical aspects (fans or pumps).
Cudos on the build. When I built one of these I only had one input port and forced the air to traverse the entire unit keeping it under the sun longer and achieving a higher temperature output. Of course as soon as you put a fan on it the length of time is shortened and the temperature will drop. Trying ti find the sweet spot of temperature and flow is the challenge. I perhaps would have either forgone the fan or put it on a speed control.
The second idea was pure genius.
This would make a great outdoor food dehydrator.
My question is your choice of fan? A lower cfm fan would slow down the heat draw and leave the air temperature higher during the day.
Great idea with the drip edge, I'm going to make one with solar panels to power the fans.
The cardboard version working is really cool
How do you stop the Plexiglas from yellowing after a couple years? Anybody have any ideas on this. This is a really great project. Well done!!
I wonder if just having the black aluminium perforated sheets suction cupped to the inside of the window would offer any heat... without the fans and boxes, and if so, would they cause more cold at night?
the black sheet is a black body absorbing solar radiation and would generate the same amount of heat whether it is sandwiched between two sheets of glass or on the inside as you suggested. and no they would not cause more cold at night.
@@rifhc TY for your reply, now I have one other question, if that sheet collects the same amount of heat with or with out being contained, would NOT having any black body, absorb the same amount of heat through the window into the room, pretty much back to where we started? And no I'm not being a smart @22 I really want to know.
@@dojodance When sunlight shines on an object (specifically long wavelengths, infrared), it causes the molecules to vibrate and thereby the object gives off heat. Heat is simply a byproduct. The object can reflect or absorb the radiation depending on material and colour. Remember light is simply radiation just like x-rays, but at different frequencies. If you want to try a simple experiment, go outside and stand in the sunlight with a white t-shirt on. Then try on a black t-shirt. You should be able to feel a difference in temperature between the two. If you don't have a black sheet of aluminum in front of the window, the light will be absorbed by various materials in the room. The objects will reflect and absorb the sunlight differently and consequently emit different amounts of heat. So by placing a black object that has good absorption properties in the direct sunlight we can try to maximize the heat generated. Does this answer your question?
Could we make the same system 1,5 M tall and use convection to have cold air entering the heater in the bottom and hot air going back in the room in the top ?
You could, but if the heat exchanger is working well, the forced air flow from the fans will improve the throughput of warm air going through the device. Also, probably the device is limited to a temperature delta/change so if the device is only capable of increasing the input vs output temp by ~25-39 degrees, you’ll have improved performance by using ‘preheated’ interior air as the input air vs much colder exterior air.
@@Stormsteed Thanks. My idea was actually to take air from the interior (so preheated) and put it back in the interior.
But just to use convection and the fact that the hot air tend to be at the top.
I think the througput of air doesn't matter much, if the air go slower it will be heated more, so same energy
@@wulfhart2653 I think you need at least one fan to move the air through to take advantage of the heat exchange effect of the box. Think about your hot attic in the summer. You may have open vents in the roof, but the removal of hot air from your attic is greatly improved if you install fan(s).
Try microfying glass to help heat metal inside
You can get an inline fan on zbay for 13 bucks that will blow 270 CF/min
Very good thanks!
Putting it inside the window won't help at all because that heat is already inside the house as long as the curtains are open. It needs to go outside, somewhere where it's not blocking a window. Putting the perforated aluminum between the panes will increase losses. Put your hand in front of the exposed glass, and your other hand behind the aluminum and tell me which feels warmer. Also, you're not looking for the highest possible exhaust temps, but best thermal output, which is achieved by more airflow. Looks like good build quality though.
It will still work because of the black paint but it won't work as well as not blocking the window
@@TwoForFlinchin1 I said it won't *help*
@@blurglide yeah I know what what you said and I'm telling you that it reads the way you did not intend so you should consider phrasing it more precisely instead of being snarky. Help is a very vague term in this context when the guy is trying to heat his home
@@TwoForFlinchin1 Help = make the room warmer than it would otherwise be without the device. This won't help to do that. It'll *work* in that you can put it in a sunbeam and it gets warm, but it won't *help* because that solar energy was already inside the house. If you put this in a glass box outside and blow house air through it, then it'll help. I'm not trying to be snarky. What is unclear?
Wouldn’t that also work with newer windows or one to put a piece of plexiglass over the recessed window box with pixie glass and an N put a hole in and out put a hole cut into a top and bottom respectively in the panel the middle of the aluminum panel in between the window in the way of the pixie glass over the recessed window pane area
Not passive is it? Passive no mechanical devices...
Perhaps that is not what passive means in this case. The fan is on or off in this heater. In active heater there would be some thermostates, maybe timers and some other automation. That's what makes it "active".
@@Teknopottu Those would make it automated. Passive is basically light shining in a window, or on a collector like this with no fans
@@blurglide That is true. I stand corrected.
@Mikowacomet Just a clarification. Active in my mind is the act of expending energy to generate heat. Like burning wood or conducting electricity through metal coils to produce heat. By placing a black body in direct sunlight to produce heat is passive. You are correct that the fans are not passive. When I was using the term passive, it was not meant to describe distributing the heat with the fans. The fans are definitely active. Sorry for the confusion.
@@rifhc By that definition, all solar energy is passive.
Speak and greek. Thanks
Use white stripes like nature
U have to use micofying glass to help heat the metal inside the box
Why people on You Tube hold their camera so close to the project I'll never know. To close. Poor video.
Video was maybe a bit rough but still informational. Better video than videos both of us made put together.