Companion forum thread to:

Explorations into Candle Stoves

Is it just me or is 6g to boil 455ml sounding remarkably efficient? If you can put up with the crap boil time...wow!

I think Mark might be really onto something here.

Hey All,

How's about firing up our Caldera Cone with a multipule flames wax burner?

I was wondering about a candle burner the first time I used my Caldera Cone.

I tried a single candle warmer and it didn't work. But, I never thought of multipule flames like "Explorations into Candle Stoves" has shown.

Back to Backpacking Light engineering ...

dplant
AT Wann'a Bee

Yeah, it is... that's the beautiful potential of wax... FYI, I was planning on doing it myself, but have found with a young son and another child on the way my time is limited...

I believe the caldera cone system may lend certain advantages to a wax burning setup... the higher internal temps of the cone should result in a more complete combustion (read more heat and less soot from a smaller wick size). Also, the nature of the cone eeks more heat capture from a smaller flame size as well.

Actually, on a SP600 stove I got tap water to tea-temp / hot chocolate temp with JUST a tea candle... not quite boiling, but didn't hardly use any fuel either...

Note, Soy Wax should hold a lot of promise... not nearly the same kinds of organic contaminants that beeswax would hold, and not nearly the inorganic contaminants that makes paraffin nasty to deal with. Basically, it should be purer than either.

HAH! I was still typing whilst David was posting...

Edited by jdmitch on 01/02/2008 07:19:14 MST.

Hmmmm...kind of interesting. I think I could put up with the low heat output but that soot would drive me crazy. Would you guys say it's more or less than the amount you would get with a typical wood burning stove?

Hi Jason

> Would you guys say it's more or less than the amount you would get with a typical wood burning stove?
Mark needs to answer as well, but from my experience I think the answer really depends on how you run your wood fire. If you are using a good gasifier and wait until the initial flames die down a bit, then I think a clean-running gasifier would be cleaner. I THINK.

Jason,

I think the soot is about equivalent to cooking over a regular wood fire. I haven't used a gasifier type stove, but they would appear to be more efficient and less sooty, so I would agree with Roger.

The major problem I found was the not so much the soot, but the fumes especially after extinguishing the stove. The wax stays very hot long after the stove is out and as the photo in the article shows there is a noxious cloud released if you remove the snuffer too soon. Try blowing out a candle and watch the plume that rises from an eighth inch wick. Now multiply by 30 or 40 to get a small idea of the smoke and fumes you get from a small stove.

Now if one could figure a way to feed a small amount of wax in as needed this would help. Also, if someone is clever enough to "gasify" the wax with a preheat tube or some such arrangement like liquid fuel stoves have, then one would have a potentially great stove.

Also, as far as the 6 grams of wax to heat water to boil- I have found that it takes about 6 gm of canister fuel to do the same thing which is consistent with the estimated heat capacity of the two fuels.

And I have not tried the cone with a candle, but one potential problem I see is that the cone is a "low oxygen" area (as the TrailDesigns folks note) and this could be problematic. But it is probably worth a try.

-Mark

Edited by markhurd on 01/02/2008 20:41:09 MST.

Yeah, the amount of soot I got from my trial was slightly less than I would have on a basic wood stove (something similar to the J Falk or Nimblewood)

"And I have not tried the cone with a candle, but one potential problem I see is that the cone is a "low oxygen" area (as the TrailDesigns folks note) and this could be problematic. But it is probably worth a try."

Low-Oxygen would only be an issue if you're vaoprizing fuel at a rate faster than it can oxidize (aka combust / burn).

The key is to keep the fuel-vaporization rate lower than the oxygen intake rate. If this is maintained the higher combustion area temps and longer heat retention time would make it advantageous.

"Also, if someone is clever enough to "gasify" the wax with a preheat tube or some such arrangement like liquid fuel stoves have, then one would have a potentially great stove."

Hmm... I wonder what would happen if one paired wax with a BB... probably wouldn't be true gasification but could get interested and be able to burn at a higher rate than the cone...

A doughnut shaped pot, raised off the ground, could provide air to the inside of a circle wick.

Ryan,

Interesting you should mention..., I recently built a donut prototype, but haven't had a chance to test it. I'll post the result when I do but it is likely to be a while before I get to it.

-Mark

Mark and Ryan,

I've been thinking about making an alcohol stove with a donut shape ever since I made my first one (a Pepsi-G).

Mark, what did you use for the weld? Please don't say JB-weld (can't find that in Aus).

Adam, if you're willing to pay for shipping, I'll box up as many as you like and send them out to you. The two part system comes in at about 70g for shipping calculations. The package seems to cost about $8-10. Maybe less if some power shopping techniques were employed.

Lemme know.

-Michael

Sorry, Adam,- I used JB-Weld to make the join. JB-Weld is just a heat resistant epoxy. ( up to about 350 degrees C, I think,) There must be an equivalent in Aus. I'd check automotive parts shops. They use it to mend engine parts.

The pictured stove has been used as an alcohol stove a couple time, but tends to burn too fast and has too large a flame pattern for the Heineken or Foster's can that I was using for the test. I think a larger pot might work well.

Anyway, my plan was to check it out as an alky stove and then fill it with wax and flat wick to make a circle-wick stove out of it for testing.

-Mark

Edited by markhurd on 01/04/2008 20:32:44 MST.

Hi Mark and Roger,

Thanks for a great article I enjoyed reading it, I found it interesting that the waxes have higher heating value than propane/butane fuels and can be as efficient. I have done a lot of testing on canister stoves and with a non flux ring pot I use about 6g of canister gas to boil 0.5l of water. One thing that I have noticed is that with both canister stoves and alcohol stoves it is not less efficient to take longer to boil water but it can be much less efficient to boil too quickly.

I think you might find this interesting. I recently ran some tests on an side burner alcohol stove that I made, with a std aluminium pot and the same stove with a 1.5l JetBoil pot the std pot used 17.18g of denatured alcohol to raise 0.5l water 80C and the JetBoil pot only used 12.4g of denatured alcohol to do the same, but this dramatic increase in efficiency was not the same with other alcohol stoves.

I have done similar work on a Donut stove ( I called mine a central flue stove) I made it out of a piece of bar stock aluminium ( see picture below), it works ok but needs some tuning, the flame is a bit stronger than I would have liked because I think it has too much thermal mass.

Tony

Tony,

Nice stove!

You know I have really been thinking that I should give up on all of this stove experimentation and just build a better pot. I seem to recall that you were working on something along that line yourself a while ago, like cutting down a Jetboil pot I think. Anyway thanks for the info on the flux ring.

-Mark

JB weld is available in Australia. I have bought some at Bunnings or K Mart.
That coincided with me losing interest in making stoves...
Franco

Hi Mark,

"You know I have really been thinking that I should give up on all of this stove experimentation and just build a better pot. I seem to recall that you were working on something along that line yourself a while ago, like cutting down a Jetboil pot I think."

Yes I removed the mounting ring from a JetBoil 1l pot and I have plans to cut it down to make it a 550 ml pot but have not done it yet as I have been distracted by many other stove projects and family life. I did try the 1l pot on a Gram weenie alcohol stove but it did not work that well, I guessed that the small diameter flux ring inhibited the air flow causing poor combustion, I am thinking about a making a gram weenie with the holes lower down to see if that helps, I will do some more work on the problem soon, I have had more success with alcohol stoves with the 1.5l pot is much larger which allows more air flow.

I have some alcohol mixing questions that I would like to ask you could I PM you.

Thanks

Tony

Adam,
JB Weld is definitely available in SA at KMart, any problems let me know and I will try and get you some

Hey Mark & Rodger,
Thanks for the feedback. Well, I'm still an alcohol-stove-guy at heart and if I have to put up with soot, I think I'd rather carry a wood stove. But, as a person who believes that every avenue must be explored, I enjoyed the investigation into candle stoves.

Have you considered trying the Primus ETA pot? It appears to be wider than the Jet Boil and has a ring under the fins to protect them. I've heard reports that it halves the boil time with an alcohol stove.