Stove Calculator v.3

In my latest video, I discuss some very basic stove science, the energy density of wood, and the idea of building a solar powered heater. It also showcases the latest version of my stove calculator spreadsheet.

Download version 3 of the stove calculator. I hope you find these calculations in your own stove building endeavors.

One thing that I failed to really drive home in the video was a better propane vs. wood comparison. I gave the propane energy in BTU/gal, it converts to 21698 BTU/lb, quite a bit higher than that of wood.

A friend of mine on YouTube, boyntonstu, has a great way to illustrate the difference between heat and temperature. First, I think we all agree a lit match would have a higher temperature than our body. Now, which could melt more ice cubes? That, my friends, is the difference between heat and temperature.

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Stove Calculations and Live Broadcast

This week’s video is my live broadcast attempt #2. It went much better than the first, it’ll probably take me a few times to doing this to loosen up a bit on camera. Here’s the video in case you missed it live:

The next time I do this, I’ll announce it a week ahead of time so we can get a few people in the chat room and make it more than me rambling in front of a camera. Feel free to join in. Most of my subscribers are into wood stoves, alternative energy, electronics, and outdoor sports like hunting and fishing. If you are interesting in those kinds of things, it should be a fun way to hang out and make friends.

As I mentioned in the video, I’ve been working on a spreadsheet that does some stove / boiler calculations. Here’s the spreadsheet for you to download and try: Stove Calculator.

If you are interested in having something like this as a smartphone app, let me know in the comment section on the above YouTube video. Also, let me know if you are using Android or iOS, so I’ll know what platforms I need to be able to support.

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Getting back on track

In my previous video, I had a bit of a disaster that really got me behind. Instead of building a small fire to cure the rigidizer, I’d recommend using a small amount of coals, a heat gun, or a propane torch. I ended up using a propane torch. Here’s the disaster aftermath:

This week, I’ve got the firebox completed, including fixing the damage to the top and insulating the door. Here’s my latest video that shows the repair (including extra insulation at the top of the boiler), illustrates how well my homemade rigidizer works, and how I’m beginning the hot gas to water heat exchanger:

As I mentioned in the video, in the interest of saving time, I’m using high temperature silicone adhesive instead of welding the pipes. I’ve tested it under several heating/rapid cooling conditions under direct flame, and it performs flawlessly. It also will give me the option of changing it in the future if I want to add more pipe. Here’s a view of my progress on the exchanger, I’ll have to buy a couple more pieces to complete it:

Partially constructed hot gas to water heat exchanger. Click for bigger picture.
Partially constructed hot gas to water heat exchanger. Click for bigger picture.


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DIY Outdoor Wood Boiler Temperature Observations

I recently purchased a infrared thermometer for obtaining data on my stove projects. Tonight, I let the stove come up to operating temperature and run for an hour before taking measurements. The results are interesting.

The ambient air temperature tonight is 61 *F. On the body of the stove, the temperature is between 180 and 197 *F. The stovepipe measured 343 *F. The door was really cooking at 572 *F. Coming in at the coldest was the belly of the stove at 112 *F.

I tried measuring the temperature of the grate, but it was too hot. My thermometer only goes to 716 *F. I’ll have to use a thermocouple for internal temperature readings.

From these observations, we learn a few things. First, that door must be insulated as it is bleeding heat. Second, the water tank is definitely pulling heat from the fire as the stove pipe is colder than the door. Lastly, my homemade insulation does a good job at keeping the heat in the fire.

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Secondary air injection and cooking steaks with a rocket stove

In my last video, I cooked up some tuna steaks and charcoal with a simple concrete block rocket stove. I mentioned adding a secondary air injector in that video. Here’s a picture of my fire grate with one such injector:

Secondary air injector
Note the air injector welded to the side of the grate.

I noticed that during operation, the lowest couple of holes produced nice secondary combustion jets. This gives me some ideas that I will incorporate into a new grate design that will be built from ground up with secondary air injection in mind.

Stay tuned for that, but in the mean time, here’s my latest video showing how I cook top sirloin steak on the rocket stove:

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I hope that you have found the last couple of videos informative and practical. I’ll continue using this rocket stove for testing and cooking. It is leading to something a bigger project that will tie together many of the small experiments I’ve done, so keep an eye on my youtube channel and this blog to see what I’m coming up with.

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Having fun in the great outdoors – homemade raft

Keeping kids happy doesn’t have to involve expensive toys that are cast aside in favor of the boxes they come in. After fly fishing for a couple of hours, my boys and I were laying in the sand seeing what shapes we could see in the clouds while mom fished on.

It didn’t take long for us to decide to do something different. We decided to build a raft from driftwood, lashed together with vines we pulled out of the trees. Here’s the result:

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So for a bit of work, we created something that gave us a couple hours of fun. Something tells me that my boys will have fond memories of doing things like this together when they grow up. I hope you find this as an inspiration in spending time with your kids, such experiences are educational and give precious bonding time.

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Inexpensive 2×4 Twin Bed Frame

I’m posting this little project, though it differs from most on this site. My boys have torn up their cheap metal bed frames, so I decided to build a boy proof bed frame out of 2x4s. You can often get 2×4 scraps from construction sites or building teardowns. I didn’t get this lucky, so I had to pay full price for them at one of the local building supply stores. In spite of that, this bed frame cost me about $15 to build.

Cheap and durable bed frame
Cheap and durable bed frame

In the above picture, you can see the completed frame. You will need 4 2x4s to build this. Make the following cuts:

  • 2x 77.75″ for the long side of frame
  • 3x 38.25″ for the head, foot, and brace
  • 8x 8.25″ for the legs

Now that you have made all the cuts, sand off all rough edges and surfaces. Take one of the 77.75″ pieces and one of the 38.25″ pieces. Drill pilot holes and screw the two together as you see in the picture with two screws. Do the same on the opposite end.

Lay the long side down with the shorter ends sticking up. Place the other 77.75″ piece on top, drill pilot holes, and screw it into both sides with two screws on each. Be sure everything is square as you go. Lay the frame down on a large flat surface.

Place other 38.25″ on its flat side in the dead center of the frame. This will be at the 37.375″ mark measured from the end of the long side of the frame. Drill pilot holes and fasten together with two screws on either side. This becomes the brace to hold the box spring.

Now for the legs. I found placing the frame on its side was the easiest way to do this. On the same side as the brace (note the picture), place the leg 1.5″ on the long side, drill pilot holes, and fasten with two screws. Do the same thing with the other leg, just on the short side of the frame. Do this on all four corners.

Now, drill a pilot hole near the floor side of the legs and attach the two legs together with one screw to tighten everything up. Do that on all four legs and you have a completed bed frame.

I used some latex based paint to finish mine. The box spring is supported by the legs as well as the brace. I hope those directions are clear enough. The picture probably explains it better than I do. To test it out, I placed the box spring in the frame and put the mattress on top. I weigh 160 pounds, so I sat on the bed and bounced. Then I lay down on the mattress. It seems quite sturdy, no creaking or anything.

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Upcoming Rocket Stove Furnace Video Series!

I’ve gotten hundreds of questions about my rocket stove heating system. Since a picture is worth a hundred words, videos must be priceless. I’m going to build a new outdoor rocket stove hydronic furnace and video every bit of it. This will be an improved model, both in efficiency, function, price, and appearance.

All these videos will be uploaded in abbreviated form to be viewed free of charge on my youtube channel. In these videos, I’ll cover the materials needed, how to make refractory cement, how to size and cast the stove, hooking up the water system, and getting everything running.

I may also offer a DVD for a reasonable price for those of you without high speed internet or who would like the series in offline format if I get enough interest in the following poll:

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I’m planning to begin uploading the series in November, so be sure to swing by my youtube channel from time to time or better yet, subscribe here.

Also, subscribe to my RSS feed to keep up to date with the other alternative energy experiments I conduct. I hope your visits to my blog and youtube channel are inspirational and get you closer to getting off the power grid or providing power for yourself during emergencies.

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Cheap rounded bolt fix

Ever get a rounded off bolt? Normally, I’ve JB welded a nut to it, waited for it to cure, and hope it bonded well enough to remove the bolt. On top of all that, I never have what I need and have to make a otherwise needless trip into town.

I recently bought a used vehicle and decided it would be a good idea to change the oil. As luck would have it, the oil plug bolt was rounded. I tried pounding a socket over it to remove it, but it didn’t do the trick. Upon reflection, it dawned on me that a pipe wrench can grip round pipes, so why not a rounded bolt head? Check out this video for the results:

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Simple homemade telescope

This isn’t necessarily a energy project, but it does involve saving money and doing things with your time, so I’ll go ahead and post it for what it is worth. My wife and kids have recently acquired an interest in astronomy, so I decided to build a simple telescope to see if the interest would grow. Unfortunately, the place I ordered from sent me a wrong lens so the resulting telescope isn’t quite what I had in mind. The one I ordered had a focal length of 100 cm, and they sent me a 30 cm one instead.

Homemade Telescope
Homemade Telescope

Focal length is one of the important ingredients of a telescope. To calculate the magnification, you simply divide the focal length of the objective by the focal length of the eyepiece. My eyepiece lens has a focal length of 5 cm.  Dividing my objective of 30 cm by the eyepiece of 5 cm, you obtain 6x magnification. I originally planned on 20x, and will do so when the new lens comes in.

The size of the objective also is important, the bigger the lens, the better the light gathering and resolving power. I’m using 50 mm lenses for both the objective and the eyepiece. The problem with this build was that I cannot purchase 50 mm inner diameter pipe locally.

To make up for this, I purchased some 2″ PVC pipe, which has an inner diameter of 2.047″. 50 mm is 1.96″. To make up the difference, I cut a 3/4″ piece of the 2″ pipe and cut slots at 90 degrees from each other. I then glued 1/4″ long pieces of rubber band in the center of each quarter.

Homemade lens holder
Homemade lens holder

The lens is then placed into the piece of pipe, held in place by the rubber bands.

Lens in mount
Lens in mount

To make the lens more secure and to attach the lens to the telescope tube, this lens holder is then inserted into a 2″ coupling. As the lens holder is pushed deeper into the coupling, it tightens and holds the lens in place. The coupling is then pushed onto the telescope tube and held in place by friction. This allows the lenses to be adjusted for focus. One is made for the objective and the other is made for the eyepiece. To make this simple, I used a 50 mm lens for the eyepiece. To get higher power and better images, you can use bushings to reduce the 2″ pipe to fit smaller lenses.

Lens mount attached to tube
Lens mount attached to tube

To get a more stable image, I drilled and tapped a 1/4″-20 hole in the tube so I could attach it to my portable camera tripod as seen in the first picture.  The tripod is fairly stable with the legs retracted and placed on top of a car.

1/4"-20 hole for tripod mounting
1/4″-20 hole for tripod mounting

Since the objective focal length is fairly small, this telescope has a good amount of chromatic aberration. This is caused by the glass bending different wavelengths of light at different angles. By having a longer focal length, you can lessen this effect. There are better ways of overcoming this, but it is beyond the scope of this article. The eyepiece being 50 mm causes some distortion around the edge of the lens, but you still have a good field of view in the center. As mentioned before, you can use smaller lenses that will work better for the eyepiece to overcome this. Another thing is the image will be upside down, like most telescopes will do. Here’s a picture shot through the telescope with my cell phone:

View throught the homemade telescope
View throught the homemade telescope

When my new objective comes in, I’ll take a picture of the same thing through it to compare. If I have a clear night, I’ll take a picture of the moon through it so you can see its night time performance. Hope that gives you some inspiration on building your own telescope.

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