Part 3: Using Micro Snow Stove Mk 15
This article is in four parts:
- Part 1: A Micro Wood Burning Stove For Alpine Tents – Dream or Virtual Reality?
- Part 2: Micro Snow Stove Mk 15 For Alpine Camping
- Part 3: Using Micro Snow Stove Mk 15
- Part 4: Getting The Best Out of a Micro Snow Stove Mk 15 – The Dream Becomes a Reality
Micro Snow Stove Mk 15 mounted on pole that is driven into the snow behind a communal snow pit inside a tent. Note the tent is held up by a chord from an overhanging branch. Mt. Baw Baw Plateau area.
Imagine that your wonderful day of skiing, snowshoeing, or walking has ended and you walk into your tent that is pitched in the snow gums (Eucalyptus pauciflora. the ubiquitous and iconic gum tree of the Australian snow country). You are ready to retreat to your tent for some protection from the wind and snow and enjoy the warmth from your snow stove and the company of friends. This micro snow stove has very little thermal mass and is a finely tuned stove that produces wood gas (smoke) and then burns it very efficiently and quickly. It will not work well or at all unless the fuel for it is appropriately prepared and fed into the burner. By contrast, bigger stoves can easily burn wet wood once there is a big enough blaze going and a good bed of hot coals. The snow stove is a bit more delicate, but a good burn can be achieved with damp dead snow gum and the strategy for preparing and maintaining a good burn is critical to success.
To demonstrate the distinct nature of the burning process in the micro snow stove, I can establish an adequate burn that will give a cook-top temperature of 752ºF (400ºC). Then I interrupt the burn with the addition of one or two pieces of inappropriately wet wood or a piece of snow. The flame will go out, and the stove will become a smoke generator. It may just keep going like this for a long time and may not spontaneously ignite again. “…[I]t may be good for bee smoking but not much good for warmth…” The simple solution to this problem is covered below in the section entitled “Flame-out Recovery.”
What follows is pretty boring mundane stuff, but most of it is crucial to a safe, light and happy experience with a micro snow stove. I apologize to any of you experienced bushmen if I am telling you how to suck eggs.
Tool List: What to Take and What to Make?
I take a DIY bow saw, wood splitting knife, modified anvil-secateurs, spring-head nails (one per camp site), fine chicken wire staples, and a short length of a hay bale twine. With the above tools, I cut firewood sticks, make the stove mounting pole, and the split stick rails for the wood drying rack. I also cut a bush mallet for splitting wood with the knife, driving both the stove mounting pole and the wood splitting anvil into the snow inside the tent and the spring-head nail into a tree to make my firewood sawing stop. The saw can also be used to cut a tent pole and a long handle for a snow shovel.
Fuel Supply and Other Bits
In wet and cold conditions preparing for successful stove burning requires a systematic approach. “…[T]he good news is that a micro snow stove does not burn much wood so that it can be collected quickly, the bad news is that it needs to be selected sticks of good quality to make the job efficient and easy…”
This is my routine: If I have not already prepared my stove and a firewood supply, I make it the first thing to do after putting up my tent. I leave on my ski boots and wet weather gear and take out my DIY bow saw and cut my bush pole for the stove mount – about 31.5 – 23.6 in. (800 – 600 mm) long depending on the snow depth/soil depth etc. The pole may be bent and used for an advantage by angling it away from the edge of the snow pit to improve its hold in the snow.
Then I cut a solid piece 15.7 * 2.0 – 2.4 in. (400 * 50 – 60 mm) diameter section of branch to use as a bush mallet (for wood splitting etc.) and another bigger piece to use as a wood splitting anvil inside the tent. I drive it into the snow inside the tent. In bad weather, this is the place to prepare wood, by a warm fire while you wait for that first hot coffee to boil and cook dinner.
Next, I use the saw to cut selected long lengths of standing dead snow gum branches that have little rot in them. I choose solid standing dead wood and use the biggest diameters that I can manage to safely and easily split. Generally, the thicker the wood the drier it will be inside. I cut about 78.7 in. (~2000 mm) lengths of straight branches. The natural death of snow gum branches and our alpine fires give us lots of material from which to pick.
I take the branches over to a suitable bent-over live snow gum and drive in a “spring-head” roofing nail with the mallet to make a simple sawing stop to allow me to safely and quickly cut the branches into billets of roughly 15.7 in. (~400 mm) long, with no risk of cutting my fingers into pieces. To make splitting easier, I usually cut through the middle of branch junctions. I pop the billets into a supermarket bag to take back to the tent. When splitting sticks, I split symmetrically through the middle of the stick, and the branch junction as this is the plane that will be easiest to split.
Stove/Stove Pipe Location in Tent
This should be largely determined at home when you modify your tent with a stove boot or flue gland to accommodate a micro snow stove flue pipe, keeping in mind the location of your snow pit. It is not a simple choice and there is great variation in the location of stoves and flue pipes. In fact, there is probably no “best location” even for my favorite simple conical tent [see photo]. This tent has five experimental flue penetration points and all had a good theoretical reason for their placement.
For my conical tent, the quality area for multiple occupants is in a radial distribution around the center, leaving a wedge area adjacent to the slit doorway for standing entry and wet or snowy things. This area can also include a narrow snow pit for comfortable sitting, standing, boot changing, and attending to cooking duties while leaving the remainder of the tent for bedding/equipment storage. Briefly, my preference is for a near center stove location, behind the protection of the center pole (if there is one, but that is another story), with the roof penetration as close as practicable to the peak of the tent. This central location also allows me to use the tent pole as a support for the stove, particularly for my larger models that require multiple legs. This configuration gives the best distribution of radiant heat (as explained before, this stove is designed more to be a radiator rather than an air heater), and the safest location of the hot stove from trip hazards and door flap contact. It also makes the roof penetration in the most stable portion of the roof surface for stability in high winds and minimizes any issue of rain water entry to the tent/flue gland at the penetration point (whether I am using the stove or not).
The flexibility of the angle of the flue pipe opening over the flue pipe connector allows the flue pipe to be tilted at a considerable angle to the cooktop while maintaining an adequate connection with the stove. This means that the stove is potentially located in a range of position that only need to be somewhat near the vertical alignment with the flue/tent gland. Lastly, having the tent/flue gland at the highest point in the tent has two more distinct functional/safety advantage. It puts the tent penetration point as far away as possible from the stove and this allow more heat exchange to the tent air, but, more importantly, makes the flue temperature as low as possible where it passes through the tent fabric. While this stove uses a 1.6 in. (40 mm) flue pipe, I like to fit the tent with a gland that accomodates larger flue pipes as required for my larger stoves (more on these glands in Part 4).
Safety temperature test
Periodically I cautiously check the temperature of the flue pipe just below the point where it passes through the tent canopy (via a tent flue gland) using the zzzt finger test (all discussed in Part 4). The temperature at this point should be below 212ºF (100ºC). I feel most in control when I can comfortably grasp the flue pipe for a moment and feel no discomfort. This temperature should be very safe and should leave a considerable margin for the unexpected as described later. Also, consider my later comments about the flue pipe not being hot enough (in Part 4, to come).
Stove Container for Backpacking
I now pack the stove in a simple bag made from a low-tech cotton flour bag cloth. It is light and water wicking, breathable, washable and can be used as a mitt for handling hot things around the stove. This fabric does not melt.
I think it is worth explaining that my early stove designs were very focused on reducing stove body weight (Part 1, stoves m, o, p, q and s). For these stove bodies I used very light gauge titanium or stainless steel foil, and they only weighed 3.5 oz (~100 g) or less. However, the penalties for such lightweight construction were many: ugliness, intricate and tricky welding, sharp corners, the need for internal bracing, shorter stove life, the suboptimal usability of the internal stove body volume for packing stove components, and a need for a bulky, strong carry box. This box protected the stove from other packed items and also protected other items from the stove while backpacking, and it resulted in 4.4-5.3 oz (125-150 g) extra weight. The sweet irony of my “heavier” current stove design is that it eliminates all the above problems and does not weigh significantly more than the “light” stove in a box. Its rounded corners allow it to pack in smoothly and efficiently in amongst the many soft items that we carry in our backpacks. “… [T]he lightest stove does not necessarily equate to the most convenient backpacking load… [S]hape and packability matter…”
Stove Unpacking and Setup
I unpack the stove on a ground sheet or similar flat soft surface, so I don’t lose small parts or break the fused quartz glass by dropping it onto a hard surface.
Immediately after closing the empty stove body I use the ash shovel to sprinkle a small amount of sifted ash (or fine soil) into the joint between the two body parts. I also use the shovel to spread the ash evenly around the whole joint and pack it in a little. This ash greatly reduces the small amount of air leakage into the stove body via this joint and improves the stove draw and efficiency. It is not much trouble to do, and if I forget to do it before setting up the stove I can still do it while the stove is burning (with a little more difficulty), and the improvement in the stove performance is noticeable. Just imagine the air leakage that would be occurring in roll-up stoves with poorer quality butt joints that I estimate are 63.0 in. (1600 mm) long.