(Continued From Part 1.)
The Simple Wood Stove
In a small, well-insulated home, or not so well-insulated home, even if it is only a tent, heating a smaller area requires less fuel and effort to make a comfortable space in which to live. In some cases this might be just a temporary shelter during the winter months. In the 1800s, living in a small one-room wood cabin that housed an entire family meant less wood had to be cut by hand.
My grandpa raised a family of 10 in a dirt-floor cabin built from logs on his Missouri farm during the Great Depression. However crude, it was an adequate shelter that was made tolerable because of a wood stove. I remember the large scar on my mother’s left forearm, a large burn caused by scalding water heated on that stove. I am fortunate to have this history within living memory, and I shall cherish it and the wisdom that sprouted out of those humble roots.
In a contest of competing priorities that can be characterized by the often-asked question: ‘if I could only choose one gun’, the sum of the characteristics of that firearm is that it must equate to that which is the most versatile and reliable, or durable. A practical small stove must also have similar characteristics and perform the same tasks as a larger stove.
Our forefathers were well acquainted with these issues. Subsequently, those who fabricated early wood stoves were better in touch with what made any wood stove practical and valuable. Such were early designs that had to have certain characteristics that are no longer considered important parts of a modern, desirable, or useful wood stove today.
One of the most obvious characteristics of a practical wood stove that is absent in early and practical designs is a glass door. Even if Pyrex glass had been invented and while a glass door allows a fire to throw its light into a room, it is not necessary and would increase its price of production, and its use is contraindicated in practical stoves as the overall design as a practical stove must be compromised to incorporate a glass door. In a heavy, large stove intended for heating the home, a glass door that allows one to watch the fire is preferable. Yet this kind of stove is not intended for cooking and we would have another and better stove for the purposes of cooking.
A glass door must swing to the left or right to allow access in the firebox that is usually shallow in depth so that the fire can be viewed once the door is closed. Modern airtight stoves typically have gaskets on a door that open from the side. These gaskets will eventually leak or become separated from the door rendering the stove less useful as designed and therefore not as practical or reliable for a long-term off-grid situation that could last for up to a decade. Unless we have provisioned a supply replacement gaskets and high-temperature cement to service a modern and efficient stove, many of its virtues will eventually be lost once the gasket material fails.
Lower technology is indeed more sustainable technology. In the final analysis it is the more sensible technology. And this class of stove while highly efficient in terms burning all the wood gases, these stoves are also heavy, typically larger, and not as well suited for transport or for cooking. Practical wood stoves will usually have a long and narrow firebox, or it if the stove opens on its widest side, the firebox is deep allowing a maximum of fuel to be loaded. The potbelly stove is the ultimate practical stove design. The steel versions of the potbelly are generally lighter and have a larger firebox than the cast iron variety. And beware that many cast iron antique replicas are designed to burn coal rather than wood. Be sure to read the fine print.
Airtight stoves are desirable, yet when the gasket is eventually worn and air leaks it will no longer function as designed or expected. And I would prefer a firebox that can be top loaded so that a smaller and lighter in weight stove can utilize its smaller dimensions and burn a larger amount of wood relative to the given restrictions inherent to the design because of its smaller size. A potbelly stove is well known for being ‘smoky’, yet its other attributes make it the better choice for a long-term survival situation.
With a proper chimney and chimney cap installed these stoves do allow smoke in the room only when the firebox lid is opened for prolonged periods exposing the fire, or if there is a wind storm. I close the flue if winds are gusting and shut down the stove. I’ve made a few modifications to the M1941 potbelly stove, that make it a nearly airtight stove without the use of high temperature gasket materials. The details of this modification will be covered later in this article series.
Military Heaters and Wood Stoves
The M1941 that is primarily discussed is a WW2/Korean War era U.S. Army tent stove. It is the forerunner to the H-45 and shares a similar shape and function. The H-45 is an improved version of the M1941. It is taller and has a larger firebox and puts out approximately 10,000 more BTUs at its maximum output of 45,000 BTUs. The M1941 is rated at 35,000 BTUs. Form follows function. These two stoves are not identical in form yet in terms of practical purposes are functional equivalents and interchangeable. What I’ll discuss about the M1941 stove will mostly apply to the H-45.
Because these surplus stoves are increasingly difficult to find in suitable condition at affordable prices, they are expensive items. However, as I have had considerable practical experience to share about this type of stove and experience with other and less expensive stoves made from Chinesium cast iron that can break or steel made from the inconsistent metallurgy of pot metal alloys that might be used instead of virgin steel that do not hold up in the long term or the welds break, these surplus stoves are hard to beat.
The steel or iron alloy used is as important to the durability of a wood stove as it is for rifle barrels that experience extreme heat. Therefore, I can only recommend stoves that are 100 percent American-made or European-made if the stove will be durable enough to withstand daily use for a decade or more.
Our military has used a variety of tent heaters that are designed to burn primary diesel and diesel fuel variants such as kerosene, JP-8, and other low-volatility fuels similar to diesel that support military vehicles. Over time, military stoves became more specialized, lighter in weight, and less capable of handling solid fuels long term, but only as a temporary solution for a temporary lack of diesel.
Increasingly, the modern military stoves left behind the idea of depending on wood and other solid fuels as a long-term fuel supply. The H-45, the offspring of the M1941, is the closest modern military tent heater to the M1941 in its basic design. The H-45 is my second choice only because the solid fuel insert (the cast iron grate) is now very difficult to find. However, one can have a sheet of heavy gauge expanded metal cut into an approximate 12-inch diameter disc that will fit in place of the oil burner assembly, once it is removed.
A top-loaded or potbelly stove is mechanically simple thus more reliable and lighter in weight and much more efficient as a cook stove, and is in general an all-purpose wood stove. These stoves can be a bit smoky if the draw is not adequate or if the wind is directed down the exhaust pipe, yet that is a matter that is easily and mostly remedied by correctly installing the pipe and using a cap that prevents down drafts and strong winds from entering the pipe. Yet other than that, I’ve had no problems.
More modern military stoves are more space and weight-efficient and use thinner gauge sheet metal stove like the M1950 Yukon. These will usually burn out the floor after one season of use. As with the other modern military stoves, only a lightly constructed wire grate is provided with the intent of protecting the thin sheet metal from very hot coals. The result is the stove has a very short service life if solid fuels (wood or coal) are used. While I have not used the M1951 Yukon stove, I do have a secondhand report from a Master Sergeant who has used these extensively in the field.
Titanium stoves while being ultralight are not only horribly expensive, but the cooking surface is too small to be of much practical use. It is however an excellent stove for backpackers. And in my experience, any stove that exhausts its smoke with a chimney pipe less than 4 inches in diameter does not typically draw well enough to produce enough BTUs of heat, not enough for a living area when the temperatures are subzero.
Fortunately, the M1941 or H-45 can easily be modified by removing 3 screws to remove the liquid fuel burner and installing a metal grate of any kind to convert it to solid fuels, namely, wood if the heavy cast iron grate is not supplied with the stove. If the user wishes to perform the aforementioned modification, the H-45 is the better choice as it has a larger firebox and the ability to secure the top and bottom together with three wing nuts. While more expensive, the M1941 can however be found complete with the original thick cast iron grate that will last the entire lifetime of the M1941 stove. This is well worth the extra price of the M1941. Spare iron grates for the M1941 can be purchased on eBay, yet the price approaches $100.
The M1941 is the focus of this article as it is the best example available for purchase, yet the H4-5 is a good second choice. The two are very closely related and what applies to the M1941, mostly applies to the H-45. As I can easily perform the modification to convert the H-45, I would choose this stove instead. Yet before you buy any wood stove, in Part 3 I’ll present my real-world account of how well an unmodified M1941 stove will perform in extreme cold weather.
(To be continued tomorrow, in Part 3.)