Explorations into Candle Stoves

Wax has a reasonably high energy density and unlike other fuels it does not spill (when cold): can you make an adequate DIY stove with it?

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by Mark Hurd and Roger Caffin | 2008-01-02 01:00:00-07

Explorations into Candle Stoves

Introduction

Wax is a hydrocarbon fuel with an energy density (by weight) comparable to other fuels like canister gas and white gas. It is therefore very similar in some ways to other fuels used in our little stoves, but it has the advantage that it is a normally solid: it won't spill. Small tea-tray candles have been used for some time to keep food warm, but they are a bit too small to bring water to the boil in a reasonable time. A problem with just scaling a tea candle up is the soot generated. We explore here what can be done to improve the heating capacity and reduce the soot from a 'candle stove'.

All the experimental work detailed here was done by Forum Reader Mark Hurd. Backpacking Light Senior Editor Roger Caffin offered some advice and wrote the article text, and accepts responsibility for any errors.

What's Good

  • Robust, won't spill
  • Can be refuelled while running
  • Very cheap to make
  • Stable on the ground

What's Not So Good

  • Low in power
  • Generates considerable soot
  • Generates acrid fumes while burning some waxes
  • Generates lots of fumes after being extinguished
  • Hard to light

Background Discussion

First of all, it is obvious that candle wax burns and makes heat. Small flat candles have long been sold and used to heat 'chafing dishes', and are often known as 'tea candles'. But candle wax has one advantage over most other fuels except for those in the Hexamine class: cold wax is a solid and does not spill or leak in your pack. Compared to Hexamine-class fuels it appears to have extremely low toxicity as well. So for many situations it looks as though it might have some potential.

Just to reinforce this, we list here some properties of some the more common fuels we use, including two forms of wax - beeswax and paraffin. Be assured - there are many others.

Fuel Formula Kcal/g BTU/lb
Propane C311.0 21660
Beeswax C26-4611.0 21650
Butane C410.8 21160
Gasoline C4-12~10.4 ~18500
Kerosene C10-18~10.3 ~18300
Paraffin C19-3610.0 18000
Hexamine  7.3 12930
Ethanol CH3CH2OH6.4 12760
Methanol CH3OH4.7 9750
Dry wood  ~3.9 ~7000

Candle Stove
A candle stove with a cross-wick and a mesh pot-support

Surprise: beeswax and paraffin wax are up there with the best! But in fact that is quite reasonable because they are just higher hydrocarbons, in the same general series as propane, butane, gasoline and kerosene. Incidentally, you should treat many of the values given here with some caution as the composition of many of the fuels can vary. (Just what is in gasoline anyhow?)

But it is also known that candles do have some problems: typical candles have very small flames and make soot. Can these problems be overcome and a more powerful candle stove created?

Candle Stove
A coiled-up wick made of corrugated cardboard - it would be very sooty IF you could get it burning

Flame Design

You might think that this section should be headed 'wick design', but that would be to miss the point. What we are concerned about is the flame, not the wick. We want a flame large enough to heat water at an acceptable rate, while not emitting too much soot. Sadly, at this stage it would seem that some soot is going to be inevitable, so we will try to minimise it.

One way of increasing the flame size is to make a bigger wick. In the photo to the right we show a 'coil wick' (picture courtesy zenstoves.net). This is a big coil of corrugated carboard embedded in the wax. In fact the coil almost fills the tin, even though it can be hard to see it all under the wax. This design is not going to work very well at all. For a start, getting it lit may prove almost impossible unless you use a small blow-torch to melt enough of the wax that the wick can light. Even if we assume a slight modification so the wick can be lit, it may make a large flame but it will also generate a huge amount of soot and lots of fumes too. This is because the centre region of the wick will be releasing lots of wax vapour but this vapour won't get to burn very well: the outer wall of flame will effectively prevent any oxygen from reaching it. No oxygen means no combustion, but lots of soot (and maybe a bit of carbon monoxide as well).

Candle Stove
A newly cast stove with a cardboard Cross-Wick

The flame needs to have lots of sidewall where oxygen can mix in to support combustion. And both sides of the flame need to be open to the air: a simple ring will still leave the core without oxygen. This makes for poorer combustion and probably more fumes and carbon monoxide. So instead of a ring we look at a cross arrangement. The centre region of a cross is likely to be oxygen poor so we eliminate it. The result looks like the stove shown to the left.

Here we have a new candle stove cooling down from the casting process: the central pool of wax is still hot and clear. There are effectively four wide flat wicks here. The flat design of the wick means that the flame will be flat and will get as much air as possible. Having the four wicks out at the edge means there is minimal oxygen starvation in the centre. The four-wicks design is simple and possibly adequate in a can of this size: a larger can could have more wicks - perhaps.

How big a gap should be left in the centre of the wick? That is hard to say, and has to be judged from the flame pattern. The flames from this example may be seen in the first photo. They are perhaps a little high and smokey, but that seems inevitable with candle stoves.

Other designs are also possible: a tubular wick as shown below to the left has been tried and is called a Circle Wick. It is a simple circle of wick, as opposed to the coil wick shown before. The wick was made quite high to get good power, but there are costs to this as explained below. A Spiral Wick consisting of round 'wick' cord wound around the side of a light tube has also been tried, as shown to the right. This was meant to be similar to some alcohol stoves, but the results were not so good.

Candle Stove
A high Circle Wick stove, burning (needs mesh pot support)

Candle Stove
Spiral Wick stove, with integral pot support

Testing the Efficiency

The testing discussed here and in also the Carbon Monoxide series of articles, plus the basic chemistry of combustion, indicate that having enough air supply to the flames is vital to getting the maximum heat from the fuel. So the obvious question is how can the air supply be maximised? In addition, note that maximising the air supply to the flame should minimise the amount of soot and fumes produced. Reducing the amount of soot is clearly desirable just from the convenience point of view: consider the deposit on the bottom of this pot after boiling half a litre (one pint) of water on the stove arrangement shown above.

Candle Stove
Soot on the underside of a pot

But remember that the soot deposited on the pot is actually unburnt carbon from the fuel: it is wasted fuel and wasted energy. In fact it is the carbon in the fuel which supplies most of the energy (as opposed to the hydrogen), so the loss of power is quite significant. If all that carbon had been fully burnt in the flame instead landing on the pot as shown the stove would have given out more heat per gram of fuel. So soot is very bad for a number of reasons.

It is likely that fuel consumption will be a good guide to the efficiency of the air supply, so the three wick designs illustrated above were tested a number of times in various configurations. For all the tests results shown here the fuel used was beeswax. The reason for using beeswax is given later. The test conditions were the same for all three designs, thus:

Air Temperature75 F / 24 C
Starting water temperature60 F / 15.5 C
Finish temperature (boiling)212 F / 100 C
Volume of water16 fl oz / 455 ml
Pot1.3 liter Evernew Ti

The averaged results from several trials of each design using beeswax are as follows.

Design Wax used Boil Times Best Clearance
Cross-Wick6 g16:00 min Not measured
Circle-Wick10.5 g6:10 1.5 cm
Spiral-Wick11 g8:30 1.0 cm

Clearly the increased air supply to the Cross-Wick design means that a lot more energy was extracted from the fuel, compared to the two very inefficient round wicks where the air supply to the inside of the flame varied from very poor to non-existent. However, the Cross-Wick design was a lot slower to bring the water to the boil compared with the other two. This happened despite the probable loss of some flame energy up the sides of the pot with the Circle-Wick and the Spiral-Wick designs. We believe that this is an inevitable result of wanting to get the best possible air supply, given a finite stove area. That is, the amount of flame surface area was smaller for the cross-wick design compared to the other two.

The Circle-Wick design allowed the height of the wick to be varied easily - with a pair of scissors. It was found that wicks of 1.5 cm and 2 cm length above the rim of the container gave about the same performance, with average boil times 6:18 min and 6:10 min respectively. A wick height of 2 cm did give a boil time of 5:58 min on one occasion. Reducing the height of the wick to 1 cm above the rim gave an 8+ min boil time. The wick to pot distance was kept constant at 1.5 cm for the rest of these tests.

The performance of each stove is fairly sensitive to the height of the pot above the top of the wick. Reducing the height from 1.5 cm to 1 cm seriously extended the time to boil - in some cases to beyond the patience of the Tester. This is explained by the reduced availability of air for combustion and the much poorer flame which resulted.

Operational Considerations

All of these stoves produce a lot of wax fumes. The fumes are very unpleasant and permeate everything around. They are of course a by-product of the boiling wax. An attempt was made to create a design which would allow the fumes to be burnt, but no suitable design was found during these tests. This may leave opportunities for further experiments by someone else.

The paraffin wax put out acrid eye and throat burning fumes. This does not happen with an ordinary candle, but then, an ordinary candle does not have a flame of the size seen here. The beeswax fumes are somewhat acrid, but mostly cloying. Beeswax candles have always been favoured by the more affluent in times past, and this is also why beeswax rather than paraffin wax was used for the tests reported above. However, beeswax apparently has a reputation of attracting bears: residual organics from the honey vaporising from the wax is one reason. Just the smell of the beeswax stove in your pack might also be enough to attract bears too: they have a very sensitive sense of smell.

Candle Stove
A snuffed stove emitting lots of fumes

As mentioned above, in general the stoves made a sooty mess of the pots, and if the soot included some wax condensate it was very hard to clean the pots afterwards. And of course the stuff makes black marks on anything it touches: hands, clothing, gear ...

When making these stoves it is important to make sure the wick is saturated with wax. A dry wick is obviously not going to catch alight at all. But a fully impregnated wick has a fair thermal mass, which means that the stoves are all hard to light, especially the Spiral-Wick design. That one can takes several minutes of flame from a lighter to catch. This is because the flame from the lighter has to melt and then vaporise some of the wax before it can catch alight. The problem can be reduced if a thread or two from the wick is left sticking out from the main wick - provided it too has been impregnated with wax as well. If you do this you have something very similar to an ordinary candle wick.

Extinguishing one of these candle stoves is hard. The Cross-Wick design can be blown out - just, but the other two cannot be blown out. This means they have to be snuffed out. But while this extinguishes the flame (by removing the air supply), it does not stop the emission of vapour/fumes from the hot wax: that still goes on for several minutes. Now there is no flame the amount of fumes is of course even worse than before. The result can be a rather thick fog as shown here, and the fumes get into everything around the stove. In addition, the stove stays very hot for up to 10+ minutes, during which time the liquid wax can be spilt.

Material Sources

Waxes can be bought from most any craft shop and from the web, often by the pound. Sources are not given here.

The first wicks in the experiments were simply corrugated cardboard: as cheap and as simple as you can get. In fact they worked quite well, but they do have the problem that as the wax gets low the wick starts to burn. This makes a bit of extra smoke, which is not so nice. More sophisticated wicks use non-burning synthetics, although one could use cheap cotton tape as well (but it chars like the paper). Sources for synthetic wicks include:

wickstore.com -- Lots of different kind of wicks including fiberglass. They sell it by the 100+ yard spool, but more importantly they also sell 10 yard hanks for US$7 each.
Spiral-Wick stoves were made with 1/8 inch and 1/4 inch round braided fiberglass wick, by wrapping the round wick material around a small cat food can, placing the wrapped can in the center of a large cat food can and pouring molten wax in the space between.

www.flammaaeterna.com (suggested by Forum Reader Jason Klass) -- This site caters to "fire-oriented performance art", such as dancing while juggling flaming objects (er - wow!). They sell flat Kevlar/Fiberglass tape wicks in various thicknesses and widths up to 4 inches. (As an aside: these wicks also make good insulators for pots and pot handles, which is what Jason was using it for.)
Two sizes of the K1 Tape Wick, 1/8 inch by 2.5 inches and 1/16 inch by 3 inches, were used for the Circle-Wick stoves. They are stiff enough to stand up by themselves. A length of the tape wick long enough to go around the inside circumference of a small cat food can was placed in position and molten wax was then poured into the can. The wick may be cut to the desired height above the rim, but should be soaked in wax to the top. Cutting the top edge of the wick leaves a raw edge on top of the wick which should be easier to light.


Citation

"Explorations into Candle Stoves," by Mark Hurd and Roger Caffin. BackpackingLight.com (ISSN 1537-0364).
http://backpackinglight.com/cgi-bin/backpackinglight/candle_stoves.html, 2008-01-02 01:00:00-07.

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Explorations into Candle Stoves
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Benjamin Smith
(bugbomb) - F - M

Locale: South Texas
Explorations into Candle Stoves on 01/01/2008 20:59:38 MST Print View

Companion forum thread to:

Explorations into Candle Stoves

Adam Kilpatrick
(oysters) - MLife

Locale: South Australia
Candle Stove fuel efficiency on 01/02/2008 01:15:38 MST Print View

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.

david plantenga
(dplant) - F
Maybe ... on 01/02/2008 07:12:43 MST Print View

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

Joshua Mitchell
(jdmitch) - F

Locale: Kansas
Re: Candle Stove fuel efficiency on 01/02/2008 07:18:39 MST Print View

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.

Jason Klass
(jasonklass) - F

Locale: Parker, CO
Interesting idea on 01/02/2008 17:39:50 MST Print View

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?

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Interesting idea on 01/02/2008 19:49:44 MST Print View

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.

Mark Hurd
(markhurd) - M

Locale: South Texas
Re: Interesting idea on 01/02/2008 20:39:22 MST Print View

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.

Joshua Mitchell
(jdmitch) - F

Locale: Kansas
Candle in Cone on 01/03/2008 09:24:18 MST Print View

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...

Ryan Potterton
(potterpotterton@yahoo.com) - M

Locale: East Cascades
more hot air on 01/03/2008 11:01:35 MST Print View

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

Mark Hurd
(markhurd) - M

Locale: South Texas
Re: more hot air on 01/03/2008 13:58:41 MST Print View

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.donut stove

-Mark

Adam Kilpatrick
(oysters) - MLife

Locale: South Australia
Re: Re: more hot air on 01/03/2008 17:40:55 MST Print View

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).

Michael Skwarczek
(uberkatzen) - F

Locale: Sudamerica
definitely JB weld on 01/03/2008 19:44:30 MST Print View

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

Mark Hurd
(markhurd) - M

Locale: South Texas
Re: Re: Re: more hot air on 01/04/2008 19:45:52 MST Print View

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.

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
Re:Re: more hot air on 01/04/2008 19:52:35 MST Print View

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

Central Flue stove

Mark Hurd
(markhurd) - M

Locale: South Texas
Re: Re:Re: more hot air on 01/04/2008 20:31:51 MST Print View

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

Franco Darioli
(Franco) - M

Locale: Melbourne
JB weld on 01/04/2008 22:10:50 MST Print View

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

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
Re:Re: Re:Re: more hot air on 01/05/2008 03:23:58 MST Print View

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

twig .
(bretthartwig) - MLife

Locale: Australia
JB in SA on 01/05/2008 04:57:46 MST Print View

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

Jason Klass
(jasonklass) - F

Locale: Parker, CO
Candle Stove on 01/05/2008 15:05:49 MST Print View

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.

Keith Selbo
(herman666) - F - M

Locale: Northern Virginia
Re: Re:Re: Re:Re: more hot air on 01/05/2008 20:28:51 MST Print View

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.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re:Re: more hot air on 01/06/2008 00:58:15 MST Print View

Hi Tony

> needs some tuning, the flame is a bit stronger than I would have liked because I think it has too much thermal mass.
I will disagree here. I don't think the thermal mass has anything to do with the amount of flame.
If there is too much flame it means too much alcohol vapour is coming off. You could reduce this by getting the flame further away from the metal (less boiling), or by covering the top ring and using jets to restrict the flow of vapour.

Go for it!
Cheers

Bill Fornshell
(bfornshell) - MLife

Locale: Southern Texas
JB Weld in Australia on 01/06/2008 12:52:20 MST Print View

Hi Adam,

I know you have been given at least one place to look for JB Weld in Australia so this may not be necessary.

When you posted your question I sent an email to the New Zealand distributor for JB Weld to ask where it was sold in Australia. I had exchanged emails with this person a few years ago. I just got an answer back from them and thought I would still pass it on to you. This is what they sent:
====
Contact the company below who are the Australian distributor. They should be able to help you.

Matt Allen
Finishing Services
tel 61 3 9553 2522
facs 61 3 9555 4048
email matt@finishingserv.com.au

===

For New Zealand see:

http://www.jbweld.co.nz.

Edited by bfornshell on 01/06/2008 12:54:33 MST.

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
Re:Primus ETA pot? on 01/06/2008 13:49:00 MST Print View

Hi Herman,

I would like to test the Primus ETA pots and I have checked them out on the net but I have not seen them for sale yet in OZ, also my stove/pot testing is totally self funded, I will look at testing Primus ETA pots when funds become available. For a while my nephew worked at an outdoor shop and he got me some stoves including the JetBoil stove and pots at a good price but he has now moved on to another job and I have to pay near retail, prices are generally much higher here than the US.

Tony

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
Re: Re:Re: more hot air on 01/06/2008 14:36:23 MST Print View

Hi Roger,

"I will disagree here. I don't think the thermal mass has anything to do with the amount of flame.
If there is too much flame it means too much alcohol vapour is coming off. You could reduce this by getting the flame further away from the metal (less boiling), or by covering the top ring and using jets to restrict the flow of vapour."

You might be right about the moving the flame further away but restricting the flow of vapor did not work with this stove, I have tried using jets (see picture below) and the stove used its fuel even quicker than the open top. I was trying to design an inside out Gram Weenie with a central flame to improve efficiency.

As part of another project I have been building a similar alcohol stove with the very thin aluminium Red Bull cans and I have had the opposite problem of not been able to get a strong enough flame, I moved the flame closer and I now have a nice flame.

Tony
Pressured donut stove

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re:Re: more hot air on 01/06/2008 15:00:42 MST Print View

> (see picture below)

LOVE the scorch marks! Stove Testing Central!
I hope the asbestos sheet is safe though?

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
Re: Re: Re:Re: more hot air on 01/06/2008 22:21:08 MST Print View

Hi Roger,

"I hope the asbestos sheet is safe though?"

It is not asbestos, I will post what it is when I find out.

The burn marks are from brazing.

Tony

Joshua Mitchell
(jdmitch) - F

Locale: Kansas
Better Pot... on 01/07/2008 14:31:57 MST Print View

FYI, NAGear.com not only has the EtaPower™ Pots for sale but also recently listed the EtaExpress Pot 1.0L

Still 1.0L though... not sure if anyone is ever going to make a heat-exchanger pot of less than that...

Adam Kilpatrick
(oysters) - MLife

Locale: South Australia
JB weld in Aus on 01/07/2008 16:15:22 MST Print View

Thanks everyone for the response.
I'll ask a couple of mates who are mechanics if they can score me anything, and if that fails it sounds like I should head into KMart.
I went to Bunnings about 18months ago after JB weld and that 3M silver tape that is uber-heat resistant and they couldn't help me on that front. After contacting 3M (Aus) directly, they sent me a sample of a fibreglass tape which works ok, but sometimes catches on fire momentarily!

Cheers,

Adam

Monty Montana
(TarasBulba) - MLife

Locale: Rocky Mountains
Smoke and fumes on 01/16/2008 12:31:42 MST Print View

I can't stand the smoke and fumes emitted after a candle is blown out, as it seems to hang in the air forever. Then I noticed that the wick glows long after the flame is gone, and the gasified wax continues to stream off the whole time. I discovered that by touching a bit of the liquified wax to the tip of the wick immediately put an end to the smoke! So I'm thinking that the same technique could be used on the much larger wicks found on these candle stoves, maybe using a small flux aplicator brush. What to do about soot accumulation would be more of a problem for me.

Edited by TarasBulba on 01/16/2008 12:32:39 MST.

Franco Darioli
(Franco) - M

Locale: Melbourne
No fumes on 01/16/2008 17:14:30 MST Print View

To eliminate fumes when extinguishing a candle I just wet my thumb and index fingers and put the flame out with them. (try it if you have never done this) So maybe this can be extended to multiple flames by using a cap that has some wet fabric inside or something like that.
Franco

Mike Pulse
(MPboxnet) - F
Candle stoves on 02/05/2008 17:58:29 MST Print View

Ok first let me say I have used candles to cook with before. I learnt to in the military because we used candles to heat up positions in the winter. I added a canteen cup to get something hot to drink. It can be done, carefully. Secondly, I learnt from some of the older guys that if you rub soap on the cooking pot before putting it over the candle, the soot collects on the soap. Than when you clean, wash the soap off and the soot goes away easily. Please use biodegradable soap. Thirdly, if the wax is heated slightly first than used in liguid form it will operate better. How is much like a rocket engine. The wax is placed in an outer container. A inner container it where the liquid wax comes to be burned. Holes in the inner container allow the wax to flow into the center. As the melted wax burns it preheats the outer containter and allows more wax to melt. One problem, keeping the outer container from catching fire. I have some designs, not avaible tonight, but most involve simple sealing air out of the outer container.
Mike

Mark Hurd
(markhurd) - M

Locale: South Texas
Re: Candle stoves on 02/05/2008 18:53:17 MST Print View

Mike,

I would love to see your designs when you get around to it. I looked at the 2 chamber idea and saw a prototype on the web from a student at the Univ. of Johannesburg, but the link is broken now. His stove used wax chips in a hopper like area that slowly fed into the melted wax. I'm afraid my experiments were far too rudimentary.

The trick with the soap I remember from my wood fire days, but it somehow didn't occur to me with these stoves.

Thanks for your input and I'm looking forward to any designs you might post.

-Mark

Joshua Mitchell
(jdmitch) - F

Locale: Kansas
Re: Ringed Wax Stoves on 02/05/2008 19:22:57 MST Print View

Interesting... I can't wait to see something of the design. that sounds really cool.

SIMON TEW
(simontew) - F

Locale: Snowdonia/Lake District/Peaks
Vaseline as a fuel? Candle-stove revisited on 05/19/2009 07:38:14 MDT Print View

Revisitng the idea of candle stoves, would anyone happen to know the energy density of vaseline/petroleum jelly? Can't seem to find it online. And does it burn any cleaner than wax?

I ran a small test and a tiny amount of vaseline in a beer bottle top, with a small wad of cotton wool smeared with vaseline as both wick and firestarter, lit with a firesteel, burned for a long time and threw off a lot of heat. It didn't seem too sooty either, though there was just the one flame of course. It would seem to beat a candle stove in at least one respect: that of being extremely easy to light with just a firesteel.

With the area of the wad being fairly large in comparison to the size of the bottle top, you get quite a wide flame as well, comparatively speaking, though the height was fairly small - comparable to a normal candle rather than to an alcohol stove. In a normal tealight candle, the flame width is limited by the thin wick, which I would guess reduces the burn rate of the fuel and lengthens the time you wait for a brew.

I'd imagine (with the benefit of ignorance) there's some optimal size of flat, round wick (like part of a cotton make-up removal pad, say) that would increase the amount of vaseline being burned whilst balancing that against the need for the limited supply of air to give clean combustion of the fuel.

Thoughts?

Cheers, Simon

Rog Tallbloke
(tallbloke) - F

Locale: DON'T LOOK DOWN!!
Re: Vaseline as a fuel? Candle-stove revisited on 05/19/2009 10:27:12 MDT Print View

It'll get a lot hotter and burn a lot longer if you throw some twigs on top. ;-)

SIMON TEW
(simontew) - F

Locale: Snowdonia/Lake District/Peaks
Re:Throw some twigs on top .... on 05/20/2009 02:43:27 MDT Print View

Funny guy ;o)

Actually, no need for twigs, because I found this:

http://science.nasa.gov/headlines/y2003/28jan_envirorocket.htm

It could make those tough ascents a bit easier :o)

Not sure I can fit it in my pack though. And the oxygen cylinder might increase the weight a bit :o)