Part 2: Non-Electric Heating Options
If you haven't already read Part 1 of this post, you can start with electric heating options.
Electric heaters are usually only practical on-grid, with continuous use of a generator, or with a truly enormous solar array. For off-grid tiny living, direct use of fuel for heating is often more practical than using it to drive a generator. Some of these options also offer ambiance that you can't get with an electric heat source.
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Small Wood Stoves
Small solid fuel stoves (wood or coal) provide wonderful warm, dry heat, and create ambiance that can completely transform the feel of a space. They require zero electricity to function, can be used for cooking as well as heating, and can use a readily available renewable fuel source.
Since wood heat is becoming more popular in the tiny living community, small stove choices and install parts are becoming more abundant and easy to obtain. No matter the size of your tiny home, there's a tiny wood stove to match. Some have accessories like direct air, water boiler attachments, and baking ovens. See our article on the Best Small Wood Stoves for Tiny Houses for an in-depth product comparison of small stoves on the market.
Rocket mass heaters are a type of wood stove that can be a good option for heating a small cabin or off-grid space. A huge mass of soil or clay is used to soak up heat from the rocket stove's combustion gases, which provides long-lasting, efficient, even heating. Since the mass of the rocket mass heater usually weighs thousands of pounds, it's not a practical solution for any structure on wheels.
If you're considering a wood stove for a tiny space, check out Tiny Wood Stove's free guide to wood stoves for tiny spaces, which reviews considerations for sizing, sourcing, and installing a small wood stove in a tiny space.
Diesel Burners
Heaters using diesel fuel are available, which could be useful if you're already storing diesel fuel for use in a vehicle or a generator. Household diesel appliances usually use a day tank with a gravity feed supply line, but those mounted in vehicles often use pumped fuel from the vehicle's tank. Most diesel appliances can also run on bio-diesel or various kinds of waste oil. Diesel heater options could be ideal for preppers, since diesel is a versatile fuel that's easy to store in quantity. Downsides for diesel appliances include the odor, and the fact that diesel and oil can get viscous when it's cold, so you may need to heat your fuel before firing your heater.
Dickinson Marine makes a diesel variation of their Newport stove, as well as a marine diesel cookstove. Various floor mounted marine diesel heaters are available, some of which also have water coils for potable or hydronic heating.
For some tiny spaces, especially small vehicles with on-board diesel like Sprinters, a forced air diesel heater could be a good option. For smaller spaces and those located in warmer climates, the Espar Airtronic D2 for might be a good choice, with an output of 3,000 to 7,500 BTUs.
For larger spaces like tiny homes, RVs and bus conversions, the Espar Airtronic D4 tops out at around 13,500 BTUs, the Airtronic D8LC at 27,000 BTUs, and the Airtronic V7S at 41,000 BTUs.
Propane Heating Systems
Propane is a popular choice for both mobile and stationary homes. Propane is readily available for purchase in portable cylinders, or it can be delivered to larger above-ground or buried tanks. Many homes already use propane to fuel a stove or range, or a propane fueled absorption refrigerator, so using it for heat as well is an easy choice. Some propane appliances can be converted to work with natural gas, and vice versa.
Forced Air Propane Furnace
A propane fired forced air furnace provides constant, thermostatically controlled, even heating. Using propane as your primary heat source means you're dependent on connecting to utilities or hauling in fuel, but uses far less power than an electric heater.
Small Household Furnaces
For larger tiny homes, a traditional household forced air furnace with a smaller BTU rating may be a perfect fit. A ducted furnace can be hidden inside of a cabinet, while a non-ducted model is visible mounted into the wall.
Ducted furnaces distribute air through a vent and return system, so they can provide quiet, even heating throughout a structure. However, the unit itself can be fairly loud, so it's best to isolate the furnace from the living space as much as possible.
Household furnaces need to be supplied with 120 volt AC power to run the fan and the thermostat. So an off-grid tiny home would need to run the inverter 24/7 to power the fan.
RV Furnaces
For smaller tiny homes, propane fired RV furnaces tend to be more lightweight and compact than household models. RV furnaces are available in lower BTU ranges (16,000 BTU) up to the output of a smaller household unit (40,000 BTU). Non-ducted models blow heated air from a panel mounted directly on the furnace, while ducted models can be hidden in a cabinet with air routed to air vents throughout your home.
Most RV furnaces require 12 volt power, so they're ideal for tiny homes storing solar energy in a 12 volt battery bank. However, if 12 volt power is not available, a 120V AC to 12V DC converter, or a step-down transformer like this 48V DC to 12V DC transformer can be used to power the furnace.
Forced Air Furnace Considerations
To keep plumbing from freezing, homes with under-floor plumbing or water tanks should have a furnace vent and return in that area. Even the furnace is only used as a supplemental heat source (for instance, in addition to a wood stove), keeping the fan running can help circulate warm air from the living space into utility areas. Electric tank or pipe heaters can also be used, but will consume significant power. Ideally, all plumbing would be contained in the heated envelope of the living area.
Furnaces are generally fairly loud. Traditional homes typically put the furnace in the basement to muffle the noise, but that's usually not an option in a tiny home. Using a ducted model with soundproofing around the furnace can help lower the noise level.
Furnace blower fans can consume a significant amount of power, since they're running fairly continuously. If you're using a furnace to heat your home off-grid, it helps to have plenty of solar to keep your house battery topped up.
Direct-Vent Propane Burners
Direct vent propane burners are self-contained units that require little or no electricity, and draw all fresh air and vent all combustion gases through the wall behind them. Some of these burners have fire viewing windows, which can provide some ambiance in addition to heat.
The Williams Direct Vent Furnace is sold for natural gas, but can be converted to propane with an optional kit. It includes a thermostat, which is a basic feature that surprisingly few propane burners offer. The Martin Direct Vent Wall Furnace also has a built-in thermostat, and it has a ceramic viewing window so the fire is visible while the heater is running.
Dickinson Marine Newport P12000 direct vent propane fireplace (and smaller P9000) is a lightweight wall-mounted design that has a visible flame, which can add to the ambiance of the room. Since it's propane fired, the Dickinson Marine propane fireplace will continue heating your space as long as you have propane in the tank. Unfortunately, there's no thermostat, so you can only select between "low" and "high."
Another option for a small direct vent gas stove is the Mini Franklin gas stove. Its 8,000 BTU/hour rating might not be enough for primary heat in most tiny homes, but it would make a nice addition to a room for supplemental heat and ambiance.
The Jotul GF 305 is a more serious direct vent gas fireplace option in the 18,000 to 28,000 BTU range. With a free-standing cast iron body and a large fire viewing window, the GF 305 could make a nice focal point for a living area with a design similar to a wood stove, but with the convenience of gas heat.
Catalytic Heaters
Propane catalytic heaters are a popular option for off-grid spaces. A catalytic heater uses a special surface to decompose propane into CO2, water vapor, and heat without any actual flame. They provide radiant heat very similar to electric infrared heaters.
Since catalytic heaters feed from and exhaust to the living space, they can have big impacts on indoor air quality if misused. Water vapor is one of the decomposition products of propane, so catalytic heaters can cause problematic humidity build-up and condensation inside the living space. Worse, but less common, catalytic heaters can potentially use up all the oxygen in the room and create a hypoxic environment.
If you think you'll notice when you start to run out of oxygen, watch this Youtube video on hypoxia, and you'll understand why hypoxia is so dangerous. There is no feeling of suffocation with hypoxia—that feeling you get when you hold your breath is from the build-up of carbon dioxide in your blood, not from lack of oxygen. A person in a hypoxic environment quickly becomes too confused to realize what's happening. If you use a catalytic heater in a small space, it's critical that the space is well ventilated, and an oxygen sensor is a good idea.
The catalyst surface needs to be kept clean to work, so catalytic heaters should be covered when not in use.
If you like the idea of a catalytic heater, but want to avoid oxygen and moisture problems, you can go with a vented catalytic heater. A vented catalytic heater works the same as a standard one, but it uses a fan to vent the combustion gasses outside, so water vapor is removed and oxygen is replenished with outside air.
Vent-Free Propane Burners
Vent-free propane burners are available for indoor use in both freestanding and wall mount configurations. These burners don't require any electricity, but they have the same problems associated with catalytic heaters since they both feed from and exhaust into the room air. A vent free propane burner is not recommended for a small living space like a tiny home.
Hydronic Heating Systems
Hydronic radiant heating systems that are available on newer RVs are a great option for heating a tiny home. Companies like ALDE and PrecisionTemp offer systems that can provide both domestic hot water, and a separate glycol loop feeding radiators throughout your space. Hydronic heaters typically run on propane with an additional electric heating element for use when shore power is available.
Hydronic heating systems are versatile solutions that can provide even heating throughout a space or spot heating in particular areas. We'll explore some of the details of distributing hydronic heat in part 3.
Passive Solar Heating Panels
While solar electricity is an inefficient method for powering a space heater, solar heat can be captured and directly used to heat a room. Package solar heating panels are available, but often surprisingly expensive. A more cost-effective approach might be to install a DIY system into the exterior wall of your tiny house while you're building.
Since passive solar only heats when the sun is shining, you'll want to have at least one additional heat source. But if implemented well, passive solar heat can significantly decrease your need for supplemental heat. You'll be able to heat your house with a smaller, cheaper secondary heating system, and use significantly less fuel or electricity to heat your home each Winter.
