If you live in an area that has winters, it’s a great idea to have a secondary heat source that isn’t tied to the grid and can be moved to wherever you’re sheltering. This review looks at the best off-grid portable space heaters that you can pull out in an emergency, and the best choice for most people is the propane-powered Mr. Heater Big Buddy.
The most important bits:
The most common fuel types are propane, kerosene, alcohol, and organics like wood.
Most people who don’t have usable wood on or very near their property end up with propane.
Propane gives off more BTUs (amount of heat) when compared to kerosene and denatured alcohol.
Propane can last indefinitely (your tank is likely to expire before the fuel) and is relatively easy to store.
People with asthma or respiratory issues tend to do better with wood stoves and propane heaters. There are reports that kerosene heaters can cause lung irritation.
Propane space heaters will not work well above 9,000 feet of elevation because the “low oxygen” safety sensors can trip. Consider a wood or alcohol stove if you live at high altitude.
Pellet stoves are fine for daily life, but they aren’t a great prep since they require electricity.
Heaters designed for outdoor use should never be used in closed-air spaces because of carbon monoxide poisoning — this is one of those warnings you should actually listen to!
Propane and kerosene heaters designed for indoor use are generally safe, but you should have a carbon monoxide sensor in your home just in case.
Space heaters should be kept multiple feet away from blankets, furniture, and other items that can catch fire. Keep a fire extinguisher close just in case you do have a fire.
BTUs: How much heat do you need?
Heat is measured in BTUs or British thermal units. A BTU is how much heat it takes to raise one pound of water by one degree Fahrenheit. Every heater has an advertised BTU output, either as a single number or a range. It’s essential to choose a heater that can sufficiently warm up your living area or survival space.
There are two factors in determining your BTU needs. The first is the area of your house you plan to heat in an emergency. If you have a small home, it may make sense to heat the whole thing, but for larger homes it’s more economical to heat only a section. For example, if you have a large enclosed room, like a master bedroom, it may make sense to only heat that room. If you don’t have large, open spaces in your home, buying multiple small heaters may make more sense—just make sure each heater can properly heat its assigned room.
Once you’ve decided on an area, you need to determine the square footage of that area. For rectangular rooms, multiply the length and width in feet.
If you’re dealing with a circular room, measure the radius of the room (from the center to the furthest edge), multiply the radius by itself, and then multiply that number by 3.14. So if the radius is 7 feet, 7 times 7 is 49, and then 49 times 3.14 is just under 154 feet.
For a triangular room, multiple the length and width and divide by 2.
For irregularly shaped rooms, or collections of open rooms, break the space into individual sections, calculate the square footage of each one, and then add them all together.
Once you have the square footage you intend to heat, you need to figure out which climate zone you live in. The United States is divided into eight IECC climate zones for the purposes of heating and cooling.