Furnace idea.

[mikeschn]

Did you guys see the candle furnace that Paul Elkins came up with? here: http://tnttt.com/viewtopic.php?p=1050017#p1050017

Mike...

[KCStudly]

No I hadn't seen that. Looks like a Coleman lantern globe on the tall one.

Are there any baffles or other tricks going on in the upper chamber?

Looks like the lower version (the one installed thru the wall) has a pan on top, maybe use it to put a little humidity into the air to help combat cold weather dryness?

Nifty.

[mikeschn]

I'll try to find out what's going on inside that can.

Mike...

[mikeschn]

Did we ever decide what's the best way to handle stratification of heat in something tiny like a teardrop?

Mike...

[Esteban]

Interesting thread.

I think if I was doing this, I would go with one box off set from the wall a little. Then I would put a shield or partially open box around it. The shield would keep from getting burns, and would also provide an air path around your burner box for a computer fan to draw more heat off.

At the very least I would experiment with one box first and see how much heat your can get off of it. Easier to problem solve venting and sealing issues on one first.

I'm skeptical whether one box would be sufficient. With one box it would have both a fresh air inlet and an exhaust outlet. My concern is that the heat would escape too easily. Inside baffles above the candles might help.


This is a thought experiment. Unlike Mike I am not doing a real test:

In my imagination I'm thinking a three box heater, with 3 vertical boxes, could work. The bottom one, to act as a combustion chamber, for the air inlet and the burning candles. A second (middle) box for heat radiation and to baffle the rising heat. At the top a third box for more heat radiation that has the exhaust to the outside. I wonder if internal baffles in each box might help? I think if the rising hot air has to follow a serpentine path through the boxes more heat might be radiated.

Googled "cookie tin" and found the Container Store has many to choose from. 8-1/8" x 6-3/16" x 2-15/16" cookie tin are rectangular tins that could create a compact cookie tin heater. Using three of them the heater might be about 8-1/8" wide and about 19" tall. I could have used many other sizes instead.

[Esteban]

Did we ever decide what's the best way to handle stratification of heat in something tiny like a teardrop?

Mike...

If you have a Fantastic Fan in the roof/ceiling could you use it to create a gentle air current inside?

[KCStudly]

Did we ever decide what's the best way to handle stratification of heat in something tiny like a teardrop?

Mike...

That Coleman tent fan you linked to looked like a good option, or a simple 12v case fan.

Another would be running the roof vent fan on Ceiling Fan Mode (The Maxxair will run with the lid closed... not sure about the Fantastic), but then you would want to make sure you had adequate ventilation from another source (TPCE will have opening windows in each door and a full time vent from under the floor up thru the bulkhead under the rear cabinets).

[KCStudly]

I did a little scrap bin diving at work and salvaged these heat sinks that were being thrown out.


These are usually from VFD's that have been "blown up", either from inadvertent exposure to water or accumulation of powders. The capacitors and some other electrical components have PCB's in them and by CT law have to be disposed of through waste management, so when one blows they strip the boards out and take the time to separate the aluminum out for scrap.

The walkie-talkie gives an idea of scale.

I like this one the best. It is over 3 lbs and is a one piece extrusion with extra ribs on each fin.

This was after I spent some time cleaning most of the organic color and guar gum powder off.

The big one has a lot more fins that are closer together, but they are crimped into slots in the extruded base. To me this means that there is at least a potential for a thermal barrier at those joints. I rinsed this one off some, but it was much harder to clean w/o having a soft bristle brush. Over 6 lbs.


This is the smallest one. The fin heights are graduated and the sides wrap around nicely with mounting lugs at the four corners. It has small standoffs on the back that I may salvage to use for a baffle plate.


The first two should be easy to incorporate into a baffled system where the flow path is directed back and forth across different sections of the fins, making a multiple pass configuration.

I won't get to work on this idea until further down the line in my build, but I wanted to throw the pics up as food for thought.

I'm going to hang on to these until I know which one will work best for me, but I'll keep my eyes open and if I find more I will offer them up to interested parties.

[mikeschn]

KC,

Do you think those fin thingies would help with a candle heater?

Anyways, I've got 2 candle heaters ready to ship down to Rev Floyd to test in the pods. Keep your fingers crossed!



Mike...

[KCStudly]

KC, Do you think those fin thingies would help with a candle heater?

Yes. They are designed to work in the reverse; you bolt a heat producing electrical device (power supply transformer, or in the case of a VFD, a square wave inverter) to the plate side with heat transfer compound between them (to bridge the natural thermal barrier of the boundary layer between the two) and the heat is radiated out thru the fins by conduction. The fins are oriented vertically so natural convection (heat rising... usually enhanced with a fan) can dissipate the heat out of the fins.

The beauty is that this should also work in reverse. Direct the heat from the candles past the fins in a serpentine fashion and the heat will be collected into them and conducted to the plate where it can radiate out into the cabin. It is a way to expose a much greater surface area to the heat source in a smaller package.

In describing this, it occurs to me that it would be very nice to have two identical heat sinks. Attach them back to back with heat paste between. One side collects the heat and the other radiates it into the cabin.

Further, I think it would be beneficial to build the box to incorporate the heat sink(s) as one of the major surfaces, rather than just attaching it to one of them (i.e. build the box out of the heat sink, rather than attaching it to the box). This would eliminate a thermal barrier that might otherwise exist between the heat sink and the face of the box.

I wish I had another one of the medium sized sinks.

As an aside, looking at all of the different variations on the flower pot heaters, none of them actually change the amount of heat that is put into the room by the candles (all of the heat stays in the space), they just collect the heat and concentrate it in one spot giving the sense that they are putting off more heat than your basic candle.

The difference that we are talking about here (stating the merely obvious) is that we are trying to avoid being exposed to the wax fumes and consuming oxygen from the heated space, so we must extract or collect the heat, and transfer it as best we can from the source into the space. By exhausting outwardly, we will lose some heat because we will never be able to collect it all.

[Junkboy999]

Wow this is a fun thread. Only thing I worried about is, the price of cookies Tins going up now that everyone is going to make a heater out of them. What will I Use for my instruments.





Ok funny stuff aside. I know from having a bout with oxygen deprivation in April, when it was 26 Deg outside and I closed my top vent and window a little too much, that it is important to have a good fresh air exchange. Could we use a small heater like with a long inlet tube located low on the floor and vented out the side or top, to help pull out the the heavier carbon dioxide outside? This will make a siphon exact and bring in a little more cold air from the windows. Wondering what effect it would have on the candles.


A round one might be fun to try. The top two cans and the lid of the bottom one can be bolted together. It will make for better heat transfer up. You might have to unplugging the exhaust vent from the trailer to open the stack up.

[mikeschn]

I'm going the supermarket today sometime. I am going to look for round cans with cookie tin lids. I think I want to try doing a miniature version of the double barrel stove.



Terry, that looks like the triple version of that stove, with out the spaces inbetween stoves!

Mike...

[KCStudly]

Two words: popcorn cans.

I've seen the really big round tins used for specialty popcorn, usually sold around the holidays from gift catalogs.

[Ron Dickey]

Interesting thread.

I think if I was doing this, I would go with one box off set from the wall a little. Then I would put a shield or partially open box around it. The shield would keep from getting burns, and would also provide an air path around your burner box for a computer fan to draw more heat off.

At the very least I would experiment with one box first and see how much heat your can get off of it. Easier to problem solve venting and sealing issues on one first.

I'm skeptical whether one box would be sufficient. With one box it would have both a fresh air inlet and an exhaust outlet. My concern is that the heat would escape too easily. Inside baffles above the candles might help.


This is a thought experiment. Unlike Mike I am not doing a real test:

In my imagination I'm thinking a three box heater, with 3 vertical boxes, could work. The bottom one, to act as a combustion chamber, for the air inlet and the burning candles. A second (middle) box for heat radiation and to baffle the rising heat. At the top a third box for more heat radiation that has the exhaust to the outside. I wonder if internal baffles in each box might help? I think if the rising hot air has to follow a serpentine path through the boxes more heat might be radiated.

Googled "cookie tin" and found the Container Store has many to choose from. 8-1/8" x 6-3/16" x 2-15/16" cookie tin are rectangular tins that could create a compact cookie tin heater. Using three of them the heater might be about 8-1/8" wide and about 19" tall. I could have used many other sizes instead.

Steve,
He could do it. If it were designed like a rocket stove


the candle and inlet left heat goes in to a small can and up and over into a larger can the out let is to the right and out. it would save space and give off the heat of the upper pan.
the only part that worries me is fire in the cabin. I wonder if it would not be best to ether light it from outside or have a place you insert a BBQ lighter with extended fire tube (for lack of words) and have a swing down cover where you stick it in. Some people have control of the world some are clumsy!!

a fire extinguisher near buy would be as plus. I keep a glass of water near for my spent matches when I am inside.

Ron

[RandyG]

Not sure if anyone would be interested here, it's a little big for inside a TD, but people have also made stoves and heaters with ammo cans. You would need to build a heat barrier on your walls cause they can get really hot, enough to heat a large tent in freezing temps. I have had one in my 'To-build' list for a while.