This post describes a very small and simple tent stove that is stripped back to the basics for providing intense and generous heating for a small winter tent. It also has a minimalist cooking surface for snow melting, water boiling and cooking in a small pot or lay flat kettle. It can also cook and simmer in a large 1L cooking pot if required.
It fits in a family of dome stoves where the small cooking surface is a small compromise to make for simplicity, powerful radiant heat output, simplicity of fueling and an ultralight pack-friendly shape and weight of just 190g.
“It may have a place in an ultralight winter backpackers kit if you like simplicity, warmth steady slow cooking of hot drinks and food in a small tent in a winter wonderland.”
Introduction
I have posted about so many similar tent stoves that I struggled to think of a name for it. It has been developed in a long line of stoves; Experimental barrel stove from a coffee tin, Pudding Bowl Stove, Miniature Dome Stove and Miniature Dome Stove with hybrid fuel ports. To date, the hybrid stove provides the most comprehensive method of using bush sticks for tent heating and cooking while ultralight winter backpacking.
The downdraft burner of the Hybrid Stove is the most powerful burner of the two options in the one stove. It has the highest fire dome temperature, the best spread of radiant heat over the dome and the simplest gravity feeding of long bush sticks for fuel.
Consequently, I used this inverted burner, with a few small improvement tweaks (that will be transposed back the Hybrid) and made the Simple Dome Stove. It is stripped back of most of the other ‘nice-to-have’ functionality options of the Hybrid and weighs only 190g.
This stove that I call the Simple Dome Stove is very similar to the experimental Pudding Bowl Stove. However, it has been redesigned to squeeze a tiny bit more cooking space on the cooktop. It also improves the internal flame guide and the nature of the fuel entry port to maximize heat output and to prevent the dreaded reverse burning that has plagued all my downdraft stoves of the past.
“These changes from the pudding Bowl Stove design are so subtle that they could easily go unnoticed. However, the improved performance is obvious. “
It is designed to be a budget stove, very simple and quick to set up and ultralight (~190g). Without any compromise, it can provide generous heating for the people in a small winter tent. The simplicity of the stove means that it only has a small portion of the fire dome top available for snow melting, water boiling and cooking in a small pot (Example of small pot from AliExpress) or lay flat kettle.
“I figure that slightly slower cooking in the confines of a warm small tent on winter evenings, particularly in bad weather (that is so good for skiing), is not so bad. Such evenings are very long anyway. They will not seem so long when there is a strong heat radiating throughout the tent and unlimited leisurely cooking and drying of clothes.”
The simple dome stove
Here is a little Instagram video of a similar stove in action. The pot hangs over the cooktop less in the Simple Dome Stove.
How the stove works
The stove uses what I call an ‘inverted J-burner’. It can easily be started with a little bit of splintery wood and a waxie or two plus some trickery (as described later). Then the bush sticks, that are used for fuel, feed under gravity down into the fire dome via the fuel tube for a largely self-regulating hot burn.
The intense radiant heat, largely from the charcoal combustion decomposes the wood and makes wood gas that burns largely in the fire dome as it moves toward the start of the flue pipe. When the exhaust gas reaches the flue pipe it is typically above 200C and is well below 100C when it exits a 2000mm flue pipe. This means that there is a very strong stove draft to sustain hot, clean fiddle-free and efficient combustion and there is little waste of heat via the flue pipe gas. The stove needs no air control or spark- arrestor. “It simply runs flat-out all the time, but only burns about 400g of bush sticks per hour.”
The stick ends rest on a glowing bed of charcoal that is the residue of pyrolysis of the bottom of previous portions of the fuel sticks.
Results and dicussion
Self-regulating combustion
Unlike my side fed burners, this stoves combustion rate is somewhat self-regulating and has more balanced combustion of the wood and charcoal fuels.
The regulating cycle I think goes like this: As the stove makes and burns more wood gas the flue draft gets stronger. This stronger draft ‘pulls’ the flame off the ends of the burning fuel sticks. This reduces the wood gas flame and flue draft. With reduced flame, the oxygen in the incoming air can reach and react more with the charcoal bed. The increased radiant heat from the charcoal in turn impacts on the wood to produce more wood gas to support more flame and the cycle starts again.
“The up and down cycling of the wood gas combustion rate can, at times, be heard in the pulsating or chuffing sound that the stove makes. It can be quite slow pulsing at star up, but when the stove is running very hot with abundant fuel sticks loaded, the airflow rate decreases, but the velocity increases. The pulsation frequency is very fast as in the video below (the video is of the Pudding Bowl Stove, but the stove and the sound are very similar the that of the Simple stove). The pulsations are strong enough to jiggle the boiling water in the little cooking pot.”
A little Instagram video of the combustion sound.
The nature of the combustion means that there is no significant build up of charcoal and the intense heat is more evenly distributed over the fire dome, including the walls.
The new fuel/air tube
Both the fuel/air tube and the flue pipe ports have been located a little closer to the fire dome perimeter to make a little more space on the cooktop. The fuel/air tube has multiple functions that I discuss under separate headings below.
The fuel/air tube as a stick holder. A minimum length of about 75mm of the fuel tube is important to keep the unruly bush sticks in the right place to naturally feed down into the fire dome. Having a much longer tube could provide control of longer fuel sticks. However, a longer fuel tube encourages a very undesirable phenomenon of reverse burning.
“It also creates a bigger problem of what to do with a bundle of long reverse burning sticks in a small tent, if they should reverse burn. I hasten to add that so far, no reverse burning has occurred with this stove, but life is long and one needs to expect the unexpected.”
The fuel/air tube as a heat shield. The fuel/air tube could simply finish flush with the stovetop, as they did in the ski chalets stoves of my youth. However, this was appropriate when the massive blocks of wood were dropped entirely into the burn chamber. My tiny Simple Dome Stoves are specifically designed to ‘trickle feed’ long ‘lazy’ sticks down into the fire dome, much like a wood pellet stove. This means that at any time only a small portion of the loaded fuel sticks are actually burning. To my knowledge, this make my inverted J-burner tent stoves different to all others (Please let me know if you think I am wrong!).
Using long sticks makes the fuel collection and preparation and storage easy. However, if the fuel port is just a simple hole, they do not feed in so well through the hole with a keen edge. Importantly, the sticks must, for most of their time, protrude beyond the surface of the fire dome that is very hot. This will mean that some sticks, particularly dry ones, will be irradiated so strongly by heat from the stovetop that they will char. The resultant smoke will catch alight and start reverse burning.
“Just in case you think this smoke catching fire scenario is implausible rubbish, have a look at this YouTube video of a candle being lit via its smoke trail.”
Consequently, in my designs, I extend the fuel/air tube up above the stovetop to provide a radiant heat shield for the incoming fuel sticks to prevent preignition as they get close to the stovetop. Although the tube gets hot, it and the sticks are cooled somewhat by the rush of air coming in through it.
The fuel/air tube as an air director. The fuel/air tube has yet another critical function. It changes the way the air enters the fire dome. The use of the tube greatly increases the rate of combustion of the fuel in the stove and particularly the charcoal that forms at the bottom of the fuel sticks. When the tube is loosely packed with fuel sticks, it restricts the airflow a little but greatly increases its velocity and results in considerable turbulence in the fire dome.
[Video of flame at fuel port with and without fuel/air tube]
As well as turbulence causing complete clean combustion, it also distributes the heat to more of the fire dome, including the walls. The heat from the walls is the most important for radiating heat toward the tent occupants. The series of photos show how well the heat is distributed.
Here is a little Instagram video of the stove and fuel/air tube in action.
[Add a video of the stove burning with and without an air tube under the same fuel supply conditions. Show the curved black-hole style flame.]
The effect of fuel/air tube depth of penetration into the fire dome. The depth of penetration of the tube into the fire dome appears to affect the proportions of each fuel (wood or charcoal) that is consumed.
“I have once more compromised stove simplicity a little by adding a tiny simple adjustable depth setter to the tube. I just can’t resist an ultralight improvement!”
When the tube is set low, the combustion of charcoal is maximized. Conversely when the tube is lifted a greater length of the wood sticks can pyrolyse and the wood gas flame increases and more charcoal can accumulate.
Absence of reverse burning
My provisional testing of the stove with the above-modified fuel/air tube showed that it had a strong clean a stable burning action. The stove burnt well with damp wood sticks, that mimic the type of fuel that is available to winter campers. They were at first restricted to a length of ~150mm and there was no reverse burning.
“With no evidence of reverse burning, I used damp sticks that were as long as ~300mm long and still I could not provoke reverse burning. This bodes well for this simple stove design.”
Note 1: So far, for three extensive test burns I have not provoked any reverse burning or seen any incipient start if it.
Note 2: With provocation, I have achieved mild reveres burning that was simply stopped by jiggling the fuel stick to snap off the charcoal. I dried half-rotten split willow sticks for some time on my kitchen woodstove and gave them an extra blast in the microwave oven just for good measure. Such dry wood when winter mountain camping will be a rare luxury that I am sure that most could manage.
Improved flame guide
Inside the fire dome is a sloping flame guide that separates the main part of the fire dome from a smaller portion that forms a chamber through which the exhaust gas flows to the exhaust port. The new guide is more stable than the one in the pudding bowl stove or my other similar stoves.
It is an improved design that bridges across the fire dome to form the exhaust chamber. It clips on to the circumference of the fire dome flange at two places, instead of only one, as in my previous stoves.
It is more stable and provides more space for the combustion of charcoal and wood gas. It provides a small passage for the exit of the flame and combustion gas to the flue pipe port. This passage is designed to induce turbulence to aid combustion and heat exchange to the fire dome surface.
[Add a photo of improved flame guide]
Stove bottom
Currently, the stove has a clip-on supplementary stainless steel bottom as shown in the above photos. It provides mechanical support for the fuel sticks in the stove. “This is particularly important when there are those willing helpers who like to gleefully thrust the fuel sticks downwards to snap off the charcoal for quicker burning and make the stove even hotter. They learn bad habits (from me) quickly”
The clip-on-bottom also provides an extra layer of thermal protection of the aluminium foil (tart tray) outer cover that seals the stove against excessive air entry and ash leakage via this big joint. (An improved stove bottom is discussed below).
Note: The above improvements or changes described for the simple dome stove also should apply equally to it predecessors that use the same fire dome and inverted J-burner.
Stove specifications
The stove is very light (~190g) and can be carried ready to use (~150mm dia*~70mm high). Alternatively, the stove bottom can be removed to store things inside it while backpacking. The stove is designed to work with a 40mm diameter roll up flue pipe.
The flue pipe connector in the stove (the shorter one in the photo above) and the fuel entry cone (taller one) are easily removable for backpacking. They both have an ‘easy entry’ openings.
Easy stove start up
The stove was easy to start and gentle blowing down the fuel/air port on to wax supplemented tinder was enough to quickly start the stove flue pipe draft.
“One long ‘sweet nothing type breath’ was all that was needed, not so strong as to extinguish the infant flames, but enough to blow a tiny amount of warm gas into the flue pipe to initiate a strong self sustaining draft. It looks like my trick of putting a burning waxie in the flue pipe is not needed now.”
Here is a little Instagram video of the simple and pleasurably easy stove start up.
Water boiling time
The stove can boil 250 ml of water in about 5.5 min, in the pot shown above and 500 ml takes about 12 min. This should be fast enough for slow relaxed cooking and drink preparation during a long winter evening.
[Add a photo of stove boiling a lay flat kettle]
Possible improvements
Bigger fuel port or more fuel ports? For my first stove of this type, I started conservatively with a 40mm dia fuel port because I knew it worked well on the Pudding Bowl Stove. “It is hard work to make it bigger, but impossible to make it smaller.”
As aways, I am tempted to maximise the fuel port size (as in the larger fuel port for the Miniature Dome Stove). It allows the use of ever bigger fuel sticks that are quick, easy and lazy to prepare with minimal backpacked tools. “Using the bushies knee, boot, tree-forked or rock crevis ‘saw’.”
However, simply increasing the diameter will encroach on the already small cooking space. Consequently, I consider that the hole could be ‘elongated’ in a direction (and shape) that would not encroach further on the cooking space.
Bigger? It could be made so as to allow various combinations of two or more stout sticks that could be accompanied by smaller ones beside them as for the Coffee Tin Stove. This may make the fuelling even easier.
More? I could add an extra fuel port. This option seemed to work best for the Coffee Tin Stove and it is easy to cover up if not needed.
Where? I could put the extra fuel port in the top, but would it be better on the side? “I will leave you to guess where (and why) I may put it?”
Improved stove bottom? The removable stove bottom is quite fiddly to fit onto the fire dome flange. The 3 slide clips work very well, but the 5 fixed clips are difficult to coordinate (“like herding cats”) even with the luxury of a flat tabletop in a warm room. Consequently, I will make all clips ‘slide clips’ so that this task will be easy for cold snow trekkers with feezing hands and a desire for warmth and hot sweet drink to restore their energy.
Above snow stove mounts. At the risk of a little more complexity, I have added three tiny stove mounts for mounting the stove above deep snow.
This would be to keep this wonderful deep snow camping option alive for those who may later discover the fun of this unusual stove mounting method when they have a tent stove.
The three stove mounts are much simpler than the ones shown in the photo below. The new mount can be seen as a slightly darker rectangle, in the fire dome wall, below the fuel tube, in the last photo below. It is a very simple welded tube. Users can put wire such as fencing wire or coathanger wire through them to make their own connectors to attach to legs made from bush poles when and if required.
I have developed another simpler and more robust alternative stove mounting connector and will cover this in a separate stove mounting post. However, here is a photo to get your interest.
Conclusion
For me, and those that have followed my other stove posts, this post is a major milestone. The stove uses a ‘tuned’ form of inverted J-burner that simply produces high and well-distributed fire dome temperatures. It does so with such ease. It provides clean and efficient burning of lazily prepared long bush fuel sticks, with the absence of charcoal choking and dreaded reverse burning that have troubled my previous downdraft J-burner stoves.
“Having modest, but restricted cooking capacity may be a price that many ultralight winter trekkers may be willing to pay for such sweet simplicity and warmth.”
Here is a little Instagram video of the tiny stove boiling a tiny pot of water, enough for tea-for-two.
If it is not already obvious to the reader, most of these small performance ‘tweaks’ should apply directly to the Hybrid Dome Stove. It has a very similar burning action when in top-down fuelling mode. “As has happened to my designs of the past, the Simple and the Hybrid Dome Stoves may merge.”
Testing of new fuel tube in Hybrid Dome Stove. The new fuel tube worked in a similar way in the hybrid stove. It did spread the heat over the fire dome, but did not get quite as hot as the simple stove. This could have been because the hybrid was a prototype stove that has more air leaks around the side fuelling port. Also, it has a less direct path for the flue gases through the elbow fitting.
Subject to more testing, the stove seems to be able to do what it was intended to do: Weighing approximately 190g it provides simple generous heat to winter tent occupants from crudely prepared fuel sticks. It will still provide a small but effective cooking surface for slow but enjoyable cooking with no fuss. It also can have a minimal assembly time at camp.
Addendum 1
I have done more testing of the Simple Dome Stove and called this addendum 1 as I expect there will be more as I do more testing.
A charcoal eater- be careful of what you wish for!
As well as simplicity, the Simple Dome Stove was designed to burn hot and not accumulate charcoal that could block up the exhaust gas pathway. The vigorous air entry action of the downdraft J-burner aggressively burns charcoal as it is made. This means that the combined energy from the fuel wood gas and charcoal achieves my highest dome stove temperatures. Furthermore, the vigour of the airflow also distributes the heat to more of the fire dome surface than other burner configurations do.
These stove performance characteristics are very desirable for providing heat for winter tent campers. However, my extensive testing of the stove has shown me that there are some small but significant downsides to the new design:
Poorer flame-out recovery. The constant consumption of the produced charcoal prevents charcoal choking. However, it greatly reduces the amount of residual charcoal that is available for re-establishing the burner flame when refuelling of the stove is for any reason neglected.
This just means that a little more care will be needed, when required, to quickly restart the flame with wood splinters and fire starters such as waxies. “It is a small compromise that I am happy to make to have such a sweet hot stove.”
Here is a little Instagram video of the easy restarting of the stove after the refuelling has been neglected
Also, I have added an extra fuel port and cover (described below) to help to maintain a charcoal bed to improve this situation. The port has a diameter of 26mm that allows quite substantial chunks of stick to be added via this port. This means that a bed of charcoal can be formed away from the ‘blast zone’ of the downdraft burner. It also can add to the stove power if even more heat output is required for cooking and snow melting for hungry skiers.
“I think the port could be up to 50mm dia so that it could be used as the exclusive fuelling port if required. This would make the stove equivalent to the Hybrid Stove. It would also mean that the fire dome could be used as a blower stove if required. More on this later.”
Hotter stove base. The vigorous airflow of the downdraft burner displaces the thermally insulating layer of ash that would otherwise form on the floor of the fire dome, in the side fed mode of operation. This, when coupled with higher stove temperatures and increased airflow toward the floor has caused the stove base to get much hotter than in other burner configurations. My response to this change is to provide a thicker stove bottom to better manage this higher temperature. An insulating refractory pad may also be tested, but the very light ‘ash catching fence’ that is discussed below seems to work well.
I subsequently tested a coiled ‘fence’ of stainless steel ribbon to make an ash keeper on the floor of the fire dome below the fuel/air tube. It is held in place by a clip that fits on the fire dome rim. It held the ash in place quite well and should help to reduce the temperature on the bottom of the stove (measurement still to be made).
Still no evidence of reverse burning. The good news is that, so far, throughout my testing, I have not been able to provoke reverse burning with damp fuel sticks.
I subsequently tested the stove using oven-dried fuel sticks and the combustion line did move up the fuel/air tube and it was easy to prevent reverse burning by jiggling the fuel sticks to snap off the supporting charcoal stems. “Luckily, such dry wood is a scarce commodity when winter camping.”
Cooking in a 1L pot?
The newly tweaked flue pipe and fuel/ air port location allow the large cooking pot to fit onto the cooktop. It has a large overhang. However, it heated quite well and could be made safer by providing a removable supporting bracket for the overhang (Shown below.).
Tim
Other related posts:
FAQs for Simple Dome Stove
I consider this to be another cornerstone post because of the consistently high, dispersed and stable heat distributed from by the fire dome. I have added this FAQ section to collate your questions and my answers to make it a little simpler to follow particular threads.
Nick: You have come up with another winner. That’s amazing that you can’t induce a reverse burn.
Tim: No sign of reverse burning so far. It is a big breakthrough for me as it is the first of my many shallow/compact inverted J-burners to be free of reverse burning. I will try to provoke it with oven-dried sticks just for fun and will post on that.
Nick: I’m just trying to understand how this stove compares to the miniature dome 3 in 1 stove. Am I being fair if I say you trade the larger cooktop and other burn modes of the miniature dome for much easier feeding?
Tim: Yes sort of. The simple stove is really a derivative of the Pudding Bowl Stove (that lead to the 3-in-1 stove). It has the flue pipe and fuel holes tweaked a little to make just a little more space on the cooktop for the small pot or a bigger one. The top-down or horizontal fuel feeding are both easy so that is not the issue.
Nick: Is there a difference in the heat emitted from the two stoves?
Tim: Yes! There is a massive improvement in; stove temperature, the spread of heat to the walls of the dome (for body warmth) and overall more stable, balanced and strong combustion of both the wood gas and charcoal together. The normal temperature of the whole fire dome of the simple stove is equal to the peak temperature that is only achieved periodically on the top of the other stoves. Having said this about the simple stove, I expect that when the same fuel/air tube is used on the 3-in-1-stove, it should behave in exactly the same way in the ‘top-down’ fuelling mode. Hope this makes sense?
Nick: Lastly, do you still pack the simple dome stove inside the 1L custom pot & if so can the pot be used overhanging the side a little?
Tinker: The stove packs up inside its custom pot (like all the others if you wish). The real compromise is that the big pot can not safely balance on the simple stove cooktop (Correction, that was with the old Pudding Bowl Stove, but the tweaking of this design does allow the big pot to just fit on). You know how I can’t stop pushing boundaries, so I have been thinking of adding a low profile mount for a bracket to the side of the fire dome so that an inserted 90-degree titanium bracket could be used to safely support the overhang of the big pot, while still allowing the normal use of the small pot.
Hi Nick, I have tested the big pot on the stove and does fit (as a result of the tweaking. It quite happily boiled water for a coffee to celebrate the success of it. Thanks for the idea. I will add a support bracket for safety.
I also have added a series of photos of all sides of the hot fire dome to better demonstrate how good it will be as a tent heater.
Regards, Tim
Congratulations Tim!
You have come up with another winner. That’s amazing that you can’t induce a reverse burn. I’m just trying to understand how this stove compares to the the miniature dome 3 in 1 stove. Am I being fair if I say you trade the larger cooktop and other burn modes of the miniature dome for much easier feeding? Is there a difference in the heat emitted from the two stoves? Lastly, do you still pack the simple dome stove inside the 1L custom pot & if so can the pot be used overhanging the side a little?
Cheers!
Nick
Nick,
Thanks for so many good questions. No sign of reverse burning so far. It is a big breakthrough for me as it is the first of my many shallow/compact inverted J-burners to be free of reverse burning. I will try to provoke it with oven-dried sticks just for fun and will post on that.
The simple stove is really a derivative of the Pudding Bowl Stove (that lead to the 3-in-1 stove). It has the flue pipe and fuel hole tweaked a little to make just a little more space on the cooktop for the small pot or a bigger one.
The top-down or horizontal fuel feeding are both easy so that is not the issue. The real compromise is that the big pot can not safely balance on the simple stove cooktop. The stove will still pack inside the large dinner pot during backpacking. You know how I can’t stop pushing boundaries, so I have been thinking of adding a low profile mount for a bracket to the side of the fire dome so that an inserted 90-degree bracket could be used to safely support the overhang of the big pot, while still allowing the normal use of the small pot. I hope this makes sense. It will be exciting if it works! I imagine that dinner components could be rapidly prepared with boiling water from the little pot and be combined and simmered gently in the big dinner pot before serving. It will be nice gentle heat for this purpose. Most of my DIY dehydrated meals are already cooked so the ‘cooking requirement’ on the stove is really a matter of re-hydration and heating to an acceptable temperature for pleasant eating. This is rather less demanding than real cooking.
Regarding the heat emitted from the simple stove, I have left the answer to this to the last. Yes, there is a massive improvement in; stove temperature, the spread of heat to the walls of the dome (for body warmth) and overall more stable burn, balanced and strong combustion of both the wood gas and charcoal together. The normal temperature of the whole fire dome of the simple stove is equal to the peak temperature that is only achieved periodically on the top of the other stoves. Having said this about the simple stove, I expect that the same fuel/air tube was used on the 3-in-1-stove, it should behave in exactly the same way in the ‘top-down’ fuelling mode.
Lastly, I have added an addendum to the post to describe the addition of a 26mm dia side fuel port and cover that additionally allows limited side fueling of the stove as well. The reasons for doing this are in the post.
“If I put enough holes in this little stove it will end up weighing nothing.”
Regards, Tim