DIY Solar Air Heater Part #6
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- Опубліковано 4 жов 2024
- The long overdue, final instalment, Part #6 of our solar air heater.
This was a tremendously rewarding project.
I learned a lot between the time I started this project and the time I finished it.
The solar air heater I ended with is different than my original plans. As I learned, I altered the design. The size of the heater changed to maximise the use of available materials. I dropped the idea of using a solar-powered panel to power the fan. If I was off the grid, I would have gone that route, but with AC available, the small power consumption of the fan would never justify the cost of a solar power panel. I learned about the different properties of high heat paint, and what brands work on Styrofoam insulation. I learned about the balance between air flow restriction and temperature delta. I ended up changing the design of the heat chamber to reduce restriction and increase CFM. My first unit completed in 2017 produced too much heat and not enough air flow.
It is interesting to re-watch the first video in my series on this topic. Three years ago I stated that “at 12 noon on a sunny winter day at 45 degrees north, my design should produce between 4,600 - 5,000 BTU, somewhere between 1,350 and 1460 watts. I’m pleased to say the final unit is producing that and more.
If I was you I would have one one ever side of your Building, Must say Well Done I was impressed.
i agree. wrapped up in other projects now, but i totally agree.
Thank you so much for finishing this scientific project. I have been following since you started. I had built something out of 2x6's, pop cans. 1/2 of a sliding glass door etc around 2000--2015 ??? If I weren't 76 I might try to copy yours. Instead, I will just enjoy yours and admire it. Thanks for finishing it. I can rest easy. Bill Dawson
Thanks for the feedback. It is been a great learning experience. A week ago I just finished another unit, tweaking the design slightly, and improved efficiency even further. I'll release video seven in the next 10 days. Cheers. Best regards.
Brilliant..! Dwayne..Thank you.
Thank you for taking the time to comment. most appreciated.
Hi, thanks for a great video. Had a thought regarding insulation. The upper outlet is insulated so that the warm air that has left the jars is isolated from the glass. Since you have more than 30 degrees Celsius, you get a cooling effect on the hot air that goes into your workshop. This may increase the effect a bit.
Kind regards Niclas Petersson
Excellent job!
Best instructional video on line. Very Impressive
Thanks for taking the time to comment Sue
Most appreciated
Dwayne
Very informative you saved me the hassle of making any .
Hi Dwayne this is the best project on you tube,good job and good attention to the particulars.
Regards from Italy👍
Thanks for the feedback - very kind. Hello to you in Italy from Canada! Cheers
Excellent thank you for this fantastic job
Enjoyed your show thank you also ideas
Replacea conventional furnace, not really. But augment one, absolutely. Make an otherwise unheated hangar a LOT less uncomfortable, absolutely.
You have a LOT of available sun-facing space on the front of the hangar where you could install more heaters, adapting the design to fit the space of course. As you determined and as so many of these homebrew solar collectors fail to realize, air flow is far more important than temperature. So long as the air going into the space from the heater is warmer than what's already there, it's working well. Big numbers for temps are fun but not that useful, and mean that a lot of heat is getting lost from the heater itself, reradiating back outdoors. I think if you were to install an actual differential control that monitored the temp inside the hangar and turned up the fans accordingly, you could see a tremendous improvement in collector efficiency.
Also: if the hangar door were clear, the sun could shine into the space and heat it directly. No moving parts.
FANTASTIC! Love the video and editing. Love the information and science approach. Love the idea on soooooo many levels. Thank you for putting the time, energy and passion into this. Wish I was watching this with my Dad. The bio-chemist in him would have loved it, too. Looking forward to trying this off-grid without a normal power source! If you have time and inclination, I would love your thoughts/advice/pointers on an off-grid version. Thanks, again, for your enthusiasm and amazing work! 😀
Thank you for taking the time to comment. You are being very kind.
I have wanted to try a complete off-grid project, but there are only so many hours in a day, and too many ideas in my head. I’m currently working on van conversion.
Again, thanks for the feedback. It is very much appreciated.
Kindest regards,
Dwayne
@@LifeIsShortDIY ❤ Thanks for responding! Good luck with the van conversion. I'm looking forward to your video on it!! 😀
that is ingenious pure and simple
That is a dam nice unit. High Quality construction. Probably the best since I been researching.
In your final calculations you confirm it is a 16 watt blower so the max unit from blower would be 141CFM ( can confirm with amazon blower 16 watt is 141cfm unrestricted)
With all the restriction and air turbulence in the pop cans. Guessing getting a max of 60CFM so BTU would be about half of what you calculated.
Be nice if you had a Anemometer to measure the airflow at the outlet pipe.
Still a dam nice unit. Free heat is free heat but accurate BTU would help to calculate recovery cost.
Currently working on a unit so taking the best of designs. Wish I had the skills and equipment to do your Aluminum frame.
a great and understandable work, thanks!
We love ours in our off grid camp. On a cold Minus 20 day. We can walk into our camp on a sunny day in January and the drinking water we leave in the sink will not be frozen. Only takes 1 hour to warm everything up. Not an entire day. So cost over time for us. Is well improved. Our camp is angled So it collects the sun in winter throughout the entire day. All windows face the sun arch throughout the day. All the windows in winter get a peace of brown insulated foam sprayed brown and hung 1 inch away from the window as we found out leaving one against the window will crack it. We found Brown high heat paint will absorb the most amount of heat better then Black. Our Pop can Heater is 2 feet by 5 ft. Camp is 16 by 38. Single floor. And Works Every well for passive heat on a cold sunny winter day.
I agree, I find if I start my work day in the hangar a little later, say 9:30am, the units have taken the chill out of the building, and no supplementary heat is needed. The solar air heaters have taken the edge off, and continue to warm the building throughout the day. Very pleased.
Great! Saludos desde Argentina
Thanks for the feedback
Appreciated
Cheers
Great video! Please have more videos.😊
Hi Dwayne.. I'm very impressed how you combine theoritical calculations, materials, costs and execution!.. Good lesson on how any project has to be done.
I'm from México and we don't have expensive heating systems.. And electricity is much more expensive here..
This idea is just great for me to bring some heat into my home
Thanks so much!! 😊
That is great to hear Raul.
I hope that works out for you.
FIRST ! :-) GREAT BUILD ! Thank you for sharing ! :-)
it may not heat your building but it would be awesome for my poorly insulated 760 sq ft house. love your videos man! been thinking about building my own but closer to 36 by 48 inch.
Sounds like a great plan. If I was to build another one, I would continue to experiment. I would try aluminum down spouts, painted black, and then stuff the inside of the tubes with crumpled aluminum screen, the same kind of screen you would use on a screen door. I have heard some good results from a few people in Mongolia. Best of luck. Cheers
I like it.me also using the same tools for the measuring the temperature
Very good video. Informative. I will build myself a similar system. Thank you very much appreciated
Great, please share with me what you build. Cheers
I would go with a solar hot water heater and exchanger linked in unison with the unit... water holds heat longer but you would be able to utilize this excellent CFM system you have pushing the warm/hot air. Great video!
I’m interested in your thinking, but unsure how to introduce water to a system that would freeze at night, unless you are suggesting circulating antifreeze as the fluid?
@@LifeIsShortDIY you need a large hot water storage box and some math to figure much volume to keep hot all night.
Pex tubing in the floor to radiate heat up no fan required but the box is tedious to build and the flooring needs notched ,well worth it!
Great video! You can replace the beverage cans with black fiberglass cloth (matte black painted extinguishing cloth) or kevlar cloth (welding protection cloth).
Which has actually been proven to preform better ~ the cloth or the cans ?
The cloth is definitely less work / time.
@@carpenterfamily6198 The cloth makes the construction so fast that you can make several pieces a day. Highest temperatures that I have achieved are more than 110 C, on a day when outside temperature was
-20 C.
@@kansaIainen I have just finished a second unit, tweaking the design to enhance conduction even further. I should have video 7 up in the coming weeks. I am interested in experimenting with different materials as well. Please share more details on the cloth idea.
Cheers
Dwayne
@@dwayneprice956 Here is some pictures of my building my solar air heaters.
www.flickr.com/photos/kansalainen/albums/72157677956243998/with/47242587082/
Excellent 👍
thank you
I've been really excited about building several of these units (albeit with cheaper materials). Going to attempt to hook them to the central heating if the house I'm renting, which hasn't worked in years.
cool. I'd like to see how that works out.
Thanks for the video
Using a mirror as the backing to the cans and using elastomeric coating on the cans and painting them black and adding fresnel lenses to the front of the panel to magnify the heat from the sun it will put out more heat
On your parts list, you forgot to mention how many sodas you had to drink to get the cans. lol What if you attached a mirror with a hinge so you can swing it out when the sun is off to the side?
I made a small one years ago, using about 53 cans. I made it to sit on a window ledge in the house. It was an experiment and nobody was going to allow me to drill a hole in the wall so it had to be completely inside. Looking back, I realize I should have set the thermostat higher to kick on the computer fan. I set it at 120-F. I'm in a condo now, but if/when I get a house, I'll build another one using gutter downspouts. No more soda cans. I need to watch my sugar intake. lol
ha ha, love it. thanks for the comments.
Paint with Vantablack. Its the darkest black. It absorbs 98% of all light.
thanks for the tip
Pull indoor air from ceiling area to bottom of heater. Exhaust heated air at 2 ft above floor.
Agreed
my second unit does that. see video 7. cheers
Hello! Congratulations on the very interesting piece of engineering. The presented expertise is valuable. I have a question, and I'm sorry if I missed the information through the project videos:
Have you ever checked the temperature at which the polycarbonate front cover could possibly release some kind of chemical component into the air flow?
An airtight metal path would eliminate such a fear by limiting the exchange to heat exchange. However, the net air volume would be dramatically reduced from the chamber volume to a, let's say, zigzag pipe.
What are your thoughts on 1. The chemical risk and 2. The net air scaled-down?
Many many thanks!
Hi thanks for the question, and sorry for the late reply. The short answer is no. I know I keep the chamber fairly cool, relatively, and this is done with higher CFMs. But to answer your question, no, no consideration to the temperature of the polycarbonate. I can share that if I was to do a “do over” I think I would use glass. The plexiglass does not seem to be keeping up well to the elements. Dozens of hair-line cracks that I have drill-stopped. I will be keeping my eyes open for recycled single pane glass.
My personal experience is best heating is achieved with a slower airflow, that let's the air have more time in the heating tube. Too fast, and the air comes out less warm.
Add lots of thermal mass, and increase the benefits!
I'm a physicist. You DO NOT NEED pop cans!! They DON'T DO ANYTHING!!! Just make an insulated box, with one side glass or polycarbonate, and suspend in the middle depth of it a piece of flat black painted steel window screen! Then add your holes top and bottom with fans at top. It can be built ON an exterior sun-facing wall, and drill holes through the wall top and bottom, or it can free-stand if you put insulated duct hose on it. Line the inside of the box with high-temp foam insulation with an aluminum foil backing facing inward. In summer cover with a cardboard & aluminum foil batten shiny side out.
Yes I have talked with others from Mongolia about using screen. If I ever get around to making a third unit, that would be the next material that I would try.
Cheers
@Colin Mitchell
Nonsense. All you need is black metal screen suspended in the chamber. It can even be layered against the back wall. The fan takes care of the airflow. I've experimented with all these kinds and it doesn't make a bit of difference.
Why not just use 3” black drain tile instead of pop cans?
I learned about solar air heaters about a week ago. I have 2 questions I can't find answer, so hopefully someone here can.
1) if one places solar air heater on the wall like You have here at 12:30, would it not be the same ( or better?) to just install regular window there to let light inside the room?
If area of window and solar air heater are the same, I just cant see benefit of this.
What am I missing here?
In my mind, solar air heater are best utilized placed on such surfaces that are not suitable for windows (like in between 2 windows).
2) at 3:46 you made a restrictor, and I assume there is one on top of cans. Why do you use it, why not letting air circulate in front of cans?
To me it seams air in front of cans will get hot, and I know it will heat the cans, but will start to loose (small, but still usable) heat to front plexiglass.
Am I wrong in assuming that?
Thank You
Unit looks good but how did you come up with CFM? is that the fan rating? Did you use an Anemomete to measure CFM at the outlet? There is a massive amount of air resistance and turbulence in the can design. If you used the fan rated 141 CFM at best you might be getting 60cfm with all the resistance.
I wonder i fyou could put fins on it like a solar cooker and get more heat ?
What about having three inlets with fans?
Maybe I would use aluminum down pipe from gutter instead of pop cans to improve the flow.
Good morning
Thanks for your comment. There is research available online on using a variety of different materials, soup cans, pop cans, downspouts etc. I reviewed what was available (work conducted by others before me) some seven years ago. What I have learned since, largely from my Mongolia audience, is that metal screen has proven to be effective as well. Possibly better than pop cans. If I was building now, I would be exploring that path to compare the results with what I have.
Cheers
Good video. lots of good information where did you get the parts for the thermostat. Thanks
You should use thermal couplers.
I tested thermal couplers and found them ineffective for my needs. As the season change, it becomes necessary to change the threshold on when this unit comes on and off. By using the part I chose, I can change these settings as needed. Works very well. Thanks for the comment.
4 layers of Aluminium fly screen seems to produce better flow and higher temps according to their experiments on the tube.
thanks for the info. may try that in the future.
Wow it's nice project. I have few questions.
1. How many square (m2) can heat your heater?
2. How long time can be warm? How about the night?
3. Cloudy or snowy day work?
This unit has an approximate area of 1.5 meters. In perfect conditions, it could capture about 2,000 watts. We don’t have perfect conditions, and we are not pointed directly at the sun. I suspect I’m getting somewhere around 1,500 watts when the sun is unobstructed.
One thing that I have learned is that you need to minimize heat loss through the glass. An important way to do that is to keep the absorber temperature as low as useably possible - the cooler the absorber runs, the less heat will be lost out through the glass. A way to keep the absorber cooler while extracting the same amount of energy from the sun is to increase air flow.
Yes, I have seen it run even though cloud cover, but there is no magic here. At best, the sun provides us with 1,360 watts of heat per square meter. Solar air heaters don’t produce heat; they capture whatever heat is available.
@@dwayneprice956 thank you. Good luck 😉
What about connecting it to a sand battery?
The tests you refer to, did they try they type that runs the air through the channels (cans, downspouts etc) up and own and back up rather than just all the individual channels going straight up? Seeing a lot of this.
I like it, but...
what about:
* frame with foam just little more thick edge,
* and double glass,
* with edge of foam (btw, foam strip, 2 notches on it, and a wood strip over, not need to drill the glass/plexy)...
* foam around the necks (inlet - outlet),
* top edge slope, to avoid water - snow...
* small solar panel for the fan... (not sun = not fan = not heat)
* small flap gate-valve, to shut the air flow (avoid heat escape will the sun not shine..)
anyway, congratulations.
so, why not just make more and use down spouts inside?
Ikr. Or at least a length of downspout with a stack of cans on either side screwed to it.
@@johnassal5838 The downspout design looks good and also seems to deliver reasonable results plus make the build easier I like it. Haven't tried myself though
yes...finaly :)
Thanks Dwayne for your video and dedication to the project. I have always been interested in using car windshields as a solar air heater. What do you think?
I see no reason why that wouldn’t work, unless the windshield glass is designed to reflect heat, which might be the case. Something to explore for sure.
I wonder if Tin foil would work?
Heat collected per sq ft will always be the same. To increase flow, increase the number of tubes the air travels through, not the length. Wider would be better for air flow, not taller.
Thanks for the insight.
Trying to understand the placement of the thermostat sensor. It’s in the vent output? The idea being it’s right between the unit and the building? Not quite understanding the rationale. Or does the device read temps on the other side as well? Thanks!
Hi jared, the temperature probe is just inside the exhaust port of the solar air heater. So, right where the air comes into the building. I just drilled a small 1/4 inch hole, and place the probe inside the exhaust port. Kindest regards.
@@LifeIsShortDIY ok. Trying to understand the rationale for this and how it works with the thermostat (about to order one), but I’ll trust it’s working for your goal, you seem to know what you’re doing. Thanks 🙏
the other shorter design is not using a manifold . therefore utilizing airflow from the inside of the cans as well as the
outer which is the entire compartment . the long ingenius design is not using airflow from the actual compartment .
but that can be fixed very easily . what did he change any way ? not gluing the cans together would have been an
improvement and not using the manifold . but the big question is , why use outside cold air ? run air from the inside
of the house with an extra fan . then you have forced air my friend .
What do you do in the summer? I have a detached 2 car garage, and live in an area that gets hot in the summer. I’d love to do this to keep it above freezing in the winder, but I need a way to “turn it off” in summer!
Close off the ducts
What are the dimensions for the unit? Will be building one as well, but might make it bigger to reach around 10btu/hr. Thanks
Reality check: what kind of difference does it make for your building? Is there any real gain? Like you said, in a 9'x12" (3mx4m) it would be of a lot more assistance during the day, but in such a large building, does it even bring it up 1 degree? Or is it feeding a small office in the building?
On a sunny day, that corner of the building is now warmer. I have another one already built that will be installed in the coming weeks in the opposite corner, and two more planned for the area above the hangar door. Should end up with just over 30,000 BTU on the south wall.
What type of paint do you recommend. I’m building a solar pool heater with irrigation tubing.
Hi,
I used heat flat-black heat resistant spray paint, similar to what you would use on a BBQ.
Cheers
What temperature is the interior of the shop while the unit is producing 35degrees c? Is there any other heat source in the shop?
Great build Dwayne. I wonder if you could use this idea for an engine pre-heater? Still weather dependent I suppose! Lots of fun to watch. I look forward to your next project.
Neat idea, but all flights would have to happen on sunny days with no departures before noon. :-)
This was great! Gave me a lot of ideas. Really appreciate the effort.
What software were you using for illustrations?
Hi, thanks for the feedback. I use a variety of editing tools, depending upon the need:
• Google Earth (topographical overlays and fly-by animations)
• Corel Photo-Paint X5 (picture editing and video mask creations)
• Corel VideoStudio X9 (primary video editing tool)
• Free Cam Build 27159 (screen capture utility)
• Windows Live Movie Maker Version 2011 (used for video file conversions)
• Google SketchUp Version 8 (3D modeling & animation)
• Microsoft Voice Recorder Version 10 (recording narrative)
Hope that helps. Thanks again for the feedback.
Kindest regards,
Dwayne
Hi. What with pressure drop (many small hols in cans)? In Your Calculate is fan performance from products sticker?
Hi, was wondering the same. In his final calculations, confirms it is a 16w fan so max airflow would be the 141 cfm unrestricted.
The 90 degree airflow turns and pop cans internal design will create a lot of air flow restriction and turbulence. If I had to guess be about 60 cfm at outlet.
I bought a cheap $15 amazon Anemometer to test the outflow when I get mine done.
Not sure how accurate a $15 anemometer will be. Could check the airflow out of a unrestricted blow and compare to name plate rating.
That would be assuming the China made blower name plate rating is accurate.
It is the nicest frame built I have seen so far in my research.
What about summers. Do you take them off or something?
Thanks for the question
I simply unplug them in the summer. Air continues to rise and vent through the system, with little or no impact on the overall temperature in the hangar. I also use the summer time to do basic maintenance. One of my two units has developed some cracks in the Plexiglas which I have had to stop-drill. Not sure why one has cracked while the other has not. On both units I oversized the holes to ensure the screws placed no stress on the Plexiglas. Still trying to figure that one out. Dwayne
@@LifeIsShortDIY thank you for your feedback.
Merhaba
Elinize sağlık bende kendi evime yapmak istiyorum bir sorum olacak yapmış olduğunuz çerçeve içine ısı dağılmaması için izocam veya taş yünü koysak daha etkili olurmu
Paneli halen kullaniyormusunus, şunuda yapsaydım daha iyi sonuç alırdım dediğiniz birşey varmı acaba 🤔
Merhaba, sorunuz için çok teşekkür ederim.
Difernet iç malzemeleri konusunda fazla tecrübem yok. Sizi, sizin için en iyi olanı keşfetmeye ve görmeye teşvik ediyorum. Sonuçlarınızı duymayı çok isterim. Hepimiz birbirimizin deneylerinden faydalanıyoruz.
Saygılarla
Dwayne
Started watching this video. Not all the way through but looking at the temperature graph with the different styles for airflow. When you installed the cans in each row, did you offset the cans so they wouldn't all line up with the holes or did you line them up? If offset, it may act as an airflow restrictor so air is heated up in each can for a bit longer before going to the next can. Just curious on what you did.
Watched part 7 where you used 4-hole cans as well as fully cut-off tops and bottoms. Great idea for flow control.
At work we use a lot of different types of heat exchangers to either warm up a process or cool a process. One heat exchanger that we use at work uses the warmed up liquid from one process and sends it over to another exchanger to get even hotter. I'm wondering if it would be possible to warm up another solar can heater with heated air from the first pumping into it or if there is a threshold that is reached where the air cannot be heated anymore. Or maybe use the heated air to reroute back to the original to increase the heated air.
@@nickl8985 I love that kind of thinking. What I have learned from using the units in our hangar, is I don’t want more heat, I want more units. If I had an entire wall of these things it would make a dramatic difference. The building is 40’ x 44’ with 12’ ceilings. Assuming you have sun, one of these units is all that you would need for a well insulated 9’x 12’ shop. I knew that going in. what they do in a large hangar is take the “edge off”. It is really amazing when you have a cold winter day, -20C, but sunny, and it is above zero in the hangar. Cheers
Infrared laser thermometer cannot measure air temperature, only surface temperature.
Agreed
So what temperature range did you set your controller to ? ( Turn on/off )
I do change it through the winter season. Right now I have the unit turn the fans on at 45c in side the chamber, and shut off around 25 or 30c. I have played with a few different numbers. Just stand next to the unit and see what works for you. Cheers
@@LifeIsShortDIY I figure you could go mad constantly adjusting the settings. I have mine just set on a programmable on/off Timer, all run off a solar generator. If the sun is strong enough, I let it run 10 minutes on and off for 5 minutes continuously till i unplug the fan. It works well because when the fan is off, the heat has a chance to build up for the 5 minutes.
"Heat", "temperature" and "thermal energy are three different things. A pebble at 100 degrees is the same temperature as a bouldar at 100 degrees, but the boulder contains MUCH more thermal energy. Heat is how quickly thermal energy is moved. Looks to me like you picked the optimal design to increase TEMPERATURE. All else being equal, you want to increase Thermal Energy- not temperature. 3 cubic feat of 100 degree air will warm your house more than 1 cubic feet of 200 degree air (and lose less heat from radiation exiting the panel). Imagine if they turned the fan down in your furnace so the air would come out at 200 degrees instead of 110 degrees or so. More heat would go up your chimney and be lost in your ducts, and the room would also have uneven heating. Use the aluminum screen or downspout designs