We finally had a sunny day yesterday and I was able to get some real results from my solar furnace. I had to make a few changes for success though…
First of all, I discovered that the mercury switch was not sensitive enough to really work. The cold air outside was messing up the way it functioned. I could not insulate the part of the air box where the switch was since the switch has to be able to move (if you’ve never seen the setup, a mercury switch is placed on a temperature sensitive metal coil which moves and allows the mercury to open or close the switch). I decided to experiment with wiring the solar panel straight to the fan which actually worked very well. The fan only came on when the sun was out and shining pretty brightly which was precisely when the best heat was being made.
The pipes that run from the furnace to the house were white originally but it seems that enough cooling took place in the pipes to make the system not work as well as I had hoped. I painted them flat black like the rest of the system and it worked like a charm. The pipes absorbed heat from the sun while transferring the heat through the system, thus helping with the whole “hot air rises” thing.
I also discovered that I had a few air leaks around the pipes and in the holes for the air pipes in the furnace. I used silicone caulking (which will actually cure in about any temp regardless of what the instructions say) to patch all of the holes/gaps/leaks.
Once I made those three changes, I took temperature measurements of the cool air pipe from my family room floor and the warm air pipe from the furnace. My floor air was 63 deg F and my warmed air was 84 deg F! Hee-haw! Eureka! Ding Dang, y’all!
Ok, so I was pretty happy with the results. The fan kicks on and off with the sun which manages the heat pretty well. I still need to boost the power to the fan to get a little more air flow. I did some experimenting and was able to get a better temperature rise with a bit more air flow. I will probably add another cheap-o solar panel to run the fan better. I also need to find a better way to prevent backflow. I really don’t like hanging a piece of plastic in front of the vent. For now, it is working but I don’t like it as a long term solution. I have glass to build one more furnace so I will probably build it out then figure out some way to deal with both systems. Anyhow, for now, I am pleased with the solar furnace!
I last posted a week or so ago about my solar furnace. I mentioned that I needed to install the system in my window and get the fan/thermostat working. Well, my friends, wait no longer! This weekend I finished the installation of the solar furnace and even powered it with a small solar panel…but I am getting ahead of myself.
My downstairs family room has 5 windows, 3 of which face southward. A south facing panel is optimum because it gets sun almost all day as the sun progresses across the sky. I read that 20 degrees from due south results in a 5% decrease in performance. Luckily I have south windows but if I didn’t have due south, I would still try the furnace. A 5% decrease would still make things interesting. In addition to the direction, you have to consider the angle from horizontal of the panel so that it gets optimum sunlight in the winter when the sun is lower in the sky. I have read various thoughts on the optium angle but the easy one for me to remember is “latitude + 10″. Here in Charleston, our latitude is 38 degrees. 
According to this calculation then, the optimum angle from horizontal is 48 degrees. Using my trusty eyeball, I leaned the solar panel along the south wall of my house and tilted it at precisely 48 degrees. To be more exact, you should consider doing a site survey to make sure you really have things right. I will probably just mess with it until it gets the best sun. In a more permanent installation, you would want this to be much more precise. Mine is easily movable.
Anyhow, I built a box (which I insulated) to run a warm pipe and a cool pipe through my window. The thermostat and fan are inside the warm pipe inlet so the warm air should automatically rise and slowly flow across the thermostat. The rise in temperature should kick on the thermostat/fan and move the air a little better through the system. As the warm air evacuates, it will cool the thermostat and turn off the fan.
I mentioned in the last post on this topic that I could not drive the fan with a super cheap solar cell. I was rumaging through the junk bin at the office when I found a pair of fans (actually, quite a few fans) that were lower amperage than my original one. Anyhow, my new fan is rated at 12 volts and 0.16 amps. I know it will run at 9 volts so I figured I needed a solar panel that would produce 1.44 watts (i.e. 9 * 0.16). Harbor Freight sells a solar panel used for trickle charging auto batteries for $19.99. Actually, the website has it for $14.99 but in the store it is more. If I would have taken the printout to the store, they would have reduced the price. Apparently the store and website are somewhat independent. I didn’t have a printout and it wasn’t worth driving back for it so I paid $19.99. Ok, back to the story - it will produce 1.5 watts which will run my new fan. I don’t know if it always just produces 12 volts and the amps vary (because it produces differently depending on the strength of the sun) or if it produces 0-12 volts and constant amps, etc. All that is to say, I don’t know exactly what wattage is driving my fan but it turns it. 
It occurs to me as I write this that I should measure the output with my mulitmeter…but really, for now, I don’t care. The fan turns fine in sun and that is my main goal. Unfortunately, the fan will not blow the dryer vent louver open. I had planned to use a dryer vent to close the inflow when not in use. I will have to resort to the “plastic over the hole” method I mentioned in the earlier post, to prevent back-syphoning. And let me tell you, back-syphoning is real and a problem if you don’t deal with it…I quickly learned a lesson on that topic!
Ok, lots of words to describe all this. The only problem is, I have not had a sunny day since I got this thing installed. I wanted to post about this progress but I don’t have any real results yet. I will have to post again with results. I know it will make a difference, but I don’t know the extent. Stay tuned!
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In an effort to make our house a bit more comfortable and to save on the energy bill, we have begun to add insulation to the crawlspace of our 70 year old house (which is otherwise uninsulated for the most part). Our place is very odd in design. We have a many levels in our house and all sorts of nooks and crannies. Half of our basement is walk-in and finished while the other half is sub-surface and unfinished. Even within our basement, there are two levels. The crawlspace in question is under the formal living room and dining room and measures 33×13. That’s lots of words for “it’s a pretty big space and pretty dang cold in the winter”.
So, we headed to the home repair place to get insulation. Abigail saw all of the pink and some of the blue foam insulation and insisted on getting pink (which was the appropriate type for our application luckily!) So, I have been installing insulation in the crawlspace of the house. In spots, I have 5 feet of headroom while in others I have 18 inches.
Of couse, I don’t think anyone has dusted under there and spiders have enjoyed the landscape. I came out several times to breathe, covered in cobwebs. My bald head somewhat attracts them I guess, though I prefer bald to hairy in that situation. I also discovered that one branch off of the main trunk from the furnace was unconnected and heating the crawlspace. No wonder I have cold spots in the house! Anyhow, I reconnected that and selaed it up so that it works as it should. I have lots more to do but I have not yet worked up the courage to venture into spiderland again! I expect the weekend will see me back fighting the arachnid army!
Earlier this week, I posted about my solar furnace project. I can’t take all the credit for the idea of a solar furnace as they have been around for a long time. Most of them seem to be passive - relying on natural motion from the warm air rising through the system. This sort of air flow is not typically very strong (though it can be), so cannot open a louver or check valve. Just leaving the hot air pipe open is an option though physics will bite back at night or when it is not sunny outside. Just as hot air rises, cool air sinks so at night, warm air will syphon from the house backwards through the system. Some folks drape a piece of plastic over the warm air output so that the warm flow blows the plastic open a little. Cool air cannot flow back through the plastic, supposedly.
All that sounds nice, but I cannot be satisfied with simplicity when I can further complicate things with technology. Being interested in saving a buck and doing the right thing energy-wise, I replaced our old thermostat with a digital programmable one a couple of years ago. I noticed that the old thermostat had a mercury switch so I didn’t want to just throw it in the trash - instead I kept it in my stash of junk…and lucky I did. This project is prime for my sort of junk. I stripped the mercury switch and the bi-metallic temperature wire from the thermostat and connected it to an old computer fan. I am building a box that will contain the thermostat and the computer fan. The fan will pull warm air from the furnace across the thermostat. While the air is warm, the mercury switch will turn on the fan which will blow open the dryer vent (that will prevent cold-air backflow) and send warm air into my room.
Initially, I had planned to power all of this with a solar panel. My fan is a 12 volt, 0.62 amp fan (though I ran it just fine with a 9-volt battery). To drive the fan directly from the solar panel (at 9 volts), I would need a 5.58 watt panel (watts = volts * amps). I may be able to get away with a little less but the cost of a 4-6 watt solar cell would still cost somewhere around $50. I have various 9 volt wall-wart transformers from old gadgets that I no longer need. 
For now, I will just drive this system from wall power. At 9 volts, when the fan is on, it will draw around 4-5 watts - about the same as a nightlight. I can live with that.
My plan is to get all of this hooked up and running this weekend. I will post again with the final project. It is supposed to be cool this weekend so I guess the timing will be right!
Spammers have been attacking this page so I have turned off comments. If you would like to have a discussion, please post on one of the other solar furnace posts or send me an email message. My contact info is in the “about/contact page”. Sorry for the inconvenience.
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Being a cheap-skate, I am incredibly excited about doing anything I can to put a little extra green in my pocket. I have been looking online and thinking a lot about making a solar furnace to supplement our home heating. We happen to have replaced 2 screen doors with full-length windows so I was presented with a couple of large pieces of tempered glass.
You can look around online for solar furnace or passive solar heat and find tons of additional information, but basically, these things work by capturing heat and using the principle that hot air rises. I snaked clothes dryer exhaust tube side-to-side through an insulated (with sheets of styrofoam insulation) wooden box. I covered the insulation with roofing felt to make the inside of the box black (plus I knew roofing felt would live through high heat). I painted the box and the dryer hose with flat black paint so it absorbs heat very well.
Cool air from my family room floor is pulled in to the bottom of the system. The sun heats it as it sits in the tube. The heating causes it to move upward eventually running back into my family room at about waist-high level.
This version does not show a blower on it yet so air flow depends purely on the principle of hot air rising. I am working on a version that uses a small fan powered by a solar panel to move the air. I’ll post more on that later as I get the details worked out.
Anyhow, for the results…I set this in the sun at about 4:30 one afternoon. The input temp was stable at 62.8 degrees F. I then measured the output temp.
I could not believe it but my digital thermometer maxed out when the temperature got over 160 deg F. The last picture I took before it maxed out was at 157.3 deg F. I have no idea what the temperature actually got to but I saw at least a 100 deg F temperature differential!
I have some more info to post on this but it will have to wait until later this week…
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Appalachian Power has started a new program where customers can purchase renewable energy credits (RECs) to offset their carbon footprint. Renewable energy credits are created whenever a renewable energy generator makes power from renewable resources. Basically, when a wind generation station sells power to the grid, it generates these credits which are certified and sold to individuals or entities like AEP. Credits are unique so when I purchase RECs, I know that the power we bought was generated at a renewable source.
We took a vacation trip to Canaan Valley 2 years ago and were able to see some wind turbines up close and personal. They are incredible and massive and pretty neat landscape features actually…sort of like flowers springing from the mountain tops. 
Of course, I don’t live super near them but I certainly liked seeing them in action. The Eastern mountains of WV are a great location for wind turbines and I am so excited to be able to buy power from them or similar sources. WV is very much a coal state and that is fine (though I think mountain top removal is despicable), but I am particularly excited to be a part of helping to make WV an energy state. We can make clean energy here. So, we are planning to purchase RECs to offset our power consumption and make our stay on the 3rd rock from the sun a little cleaner. We currently average 1447 kwh per month so we will purchase to offset that. Our next goal, then, is to look around our house and find ways to reduce that number. Our hot water and oven are electric and I am not compelled to replace those items. We will likely have to address our normal patterns of usage and look at our other appliances as well. It should be interesting but will pay off!
Well, yesterday’s post was about bad green. Actually, green is my favorite color and there are tons of green things that I have snapped pics of this summer. These greens are much better than Soylent green.
Humans have three types of color receptors in the eye. Basically, they are for sensing red, green, and blue. In general, humans are most sensitive to greenish wavelengths. I suppose that is why greens seem so vivid (or is it just me?). I used to do some physiological research on various critters, among them, zebrafish. Zebrafish have four sensor types and are most sensitive to UV. I wonder what their favorite color is…
I guess I am sort of glad, but also bummed that a camera just rarely seems to capture colors as vividly as they are in real life. I guess that’s one of the things that makes the moment so special.
This hillside is outisde my office and has been very interesting to watch evolve in color through the summer. Right now, there are plants that are turning bright red and goldenrod has also really cropped up. Green dominates but the hillside is alive with color!
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This is my favorite green…I am trying to avoid caffeine and drink more water and milk so it’s rare that I get to enjoy any of this nectar…so sad…
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There was an old junky shelf in our basement that was pieced together with a 1×12 and a 1×8 screwed together. I hated to just burn it up but wasn’t sure what to do with it. Isaac and Abigail had a visit at their Summer camp program from the Three Rivers Avian Center where they learned about bird habitats and their bird rescue program. The kids were so interested that they suggested we make some birdhouses out of the wood. We’ve had a house wren pair that have nested in an existing house the last three years and hatched 2 sets of eggs per year. That leaves us with a lot of house wrens around. I found some plans online for a house wren’s house and our wood measured out sufficient to make 3 houses. That should hopefully help our wren-friends. I ripped the boards to width and the kids sawed them to length by hand. They did a marvelous job on the first house. Abigail primed the wood and painted it in a rainbow motif. She assured me that the birds will like it and never go to the wrong house. She also thought the bees would enjoy the colors. It is really a beautiful paint job. We’ll probbaly work on the other two houses next weekend.
Abigail was a tremendous painter through it all. She applied several coats of primer to both the house and her legs. She waited patiently for each coat to dry…at least 10 minutes or so between coats. The best part was her work with colors. She was incredibly excited with her creation…with good reason! 
She has not yet announced her design thoughts for the next houses. She is opinionated about everything though so I am sure she will let us know!
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We have an old Lawnboy 2-cycle mower that has been passed around the family for hundreds of years. It has been a great mower but it became unreliable on our watch. We decided to go shopping for a new mower and had hoped to find something easy to push on our crazy hills. I had been looking at various reel mowers but had never used one. We decided to look into it as we shopped. We found a fairly light one made by Scott’s and figured we’d try it.
It gives an awesome cut! It is easier to push than our motorzied mower and doesn’t make me smell of exhaust afterwards. The best part is that it cost only $82 compared to $250 or more for the motorized ones. It produces no pollutants and costs
us nothing in gas money. The only weakness we have found so far is that it does not do great with those weed things that stick up way above the grass. I think we are going to go shopping for a weed-whip this weekend to remedy that problem.
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This was the first rain barrel we installed. I went to a seminar put on by DNR and the city. They discussed the need, the benefits, etc and subsidized the cost. The best part about it was that it started out white. No need to paint it! I don’t like the bottom drain so much but it surely works.
My parents got some blue barrels that were originally full of vinegar. I painted them (is it that obvious?!) and hooked them up. Both drain to the location the down spouts originally fed. Don’t 
forget to install a drain! I didn’t have drains at first thinking that it wouldn’t flood too bad…well, I got a lesson in how much rain runs off of a roof in a downpour. Drains are critical unless you don’t mind the water running down your foundation.
I hooked two barrels together on the side of the house where the 
gutter drains the largest amount of roof. I could probably use 10 barrels on that area but it wouldn’t look too hot. Anyhow, I also saw some other folks who had a contraption built to allow the first several gallons to pour out rather than go into the barrels. Basically, on mine the water goes down into the big pvc pipe which holds a small plastic ball. As it fills, the ball floats up to the neck between the big and small pipes. When it reaches the top, it seals the large vertical pipe and 
redirects water into the ‘y’ and down into the barrel. There is a small leak in the big pipe so it drains ‘automagically’ between downpours. The two barrels are joined together by the hose that connects the two via their spigots. I just leave both spigots open most of the time (but I can close the individually when I want to use some water). Water will level itself between the two barrels without my intervention.
I could probably use some lessons in spray painting but it blends with the house from a distance…unless you ask Emily.
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We finally had a sunny day yesterday and I was able to get some real results from my solar furnace. I had to make a few changes for success though…
I also discovered that I had a few air leaks around the pipes and in the holes for the air pipes in the furnace. I used silicone caulking (which will actually cure in about any temp regardless of what the instructions say) to patch all of the holes/gaps/leaks.
November 24, 2008 8:46 am | 
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