Essential Guide to Fuel Burning Heaters

Fuel burning heaters often require a better understanding of the manner in which they generate heat and due to the inherent risk associated with volatile fuels a greater appreciation of safety requirements. This article will mainly look at portable space heaters, however we have looked at other fuel burning heaters on the site, for example we looked at the best pellet stoves elsewhere.

Room heaters burning kerosene, natural gas, or propane are often used. A few require permanent installation and may be vented through the wall. Most are portable and unvented. In some states and cities, unvented gas or kerosene heaters are in violation of state and local laws. Be sure to check with your local building code official before installing one. Check with your insurance company to verify that there will be no loss of coverage if you purchase and use a fuel-burning heater.

Kerosene-burning Heaters

Most kerosene heaters are portable, although some of the newer models require permanent installation and venting through the wall. This section will be limited to portable heaters, since they are the most common.

While kerosene-burning heaters have been available for several generations, they were seldom used because of safety and odor problems. Beginning in 1975, kerosene heaters of a new design began arriving from Japan. They were highly efficient-about 98-99%. They had convenient, electric ignition, and they incorporated a safety switch, which shut the heater off immediately if the unit was tipped. New refining techniques also provided a purer grade of kerosene, reducing the odor problem. In Japanese houses, however, natural ventilation prevented the accumulation of indoor pollutants generated by the heaters. Even with improved design, modem kerosene heaters are only safe when they are used in well-ventilated spaces.

Of course that was a long time ago now and space heater technology has moved on. Check out our most efficient space heater guide for the latest in top rated most efficient space heaters.

Any fuel-burning heater needs oxygen from the air to bum the fuel. People also need oxygen to breathe. A fuel-burning heater can use enough oxygen to reduce the oxygen content in the room below that needed for breathing.

Some gas and kerosene heaters feature an oxygen depletion sensor. The sensor will shut off the heater if the oxygen in the room drops below the level needed to sustain life. While it does prevent asphyxiation, the sensor does not warn of high levels of other pollutants in the air.

Both radiant and convection heaters are available. Both usually have electric ignition from batteries carried within the unit. Most bum the kerosene as it evaporates from a wick, but a few direct vaporizing models are available. The kerosene tank may be built-in or removable for filling.

Radiant heaters

Radiant heaters are usually square or rectangular. The heater’s wick, burning with a blue flame, heats the metal mantle covering it to incandescence. A polished metal reflector backing the mantle directs the heat into the room. Because of the reflector, the back of the heater does not become as hot as the front and may be placed as close as 18″ to a wall or furniture. The heat is directional, similar to an electric radiant heater. Some models have an electric fan, which can be used to circulate heat from the back of the reflector, so that they function as both a radiant and convective source.

Convection heaters

Convection heaters involve air being taken in at the bottom of the heater rises past the hot mantle and is discharged into the room. Since all surfaces are hot, the convection heater should be kept at least three feet from the nearest flammable surface or material.

Gas-fired Heaters

While not portable, unvented gas-fired heaters are sometimes used as room heaters. A gas line is connected to the heater. They may be either of the radiant or convection type, and are similar to the kerosene-burning units.

Ventilation

When any fossil fuel is burned, it produces carbon dioxide, carbon monoxide, nitrogen dioxide, sulfur dioxide, water vapor, and traces of other compounds, depending upon the contamination present in the fuel. In vented systems, such as a furnace or boiler, the by-products of combustion escape up the chimney, along with a certain amount of heat. With an unvented heater, heat stays in the room, but so do the combustion products. To be safe, these pollutants must be removed.

While not immediately life-threatening, carbon dioxide, nitrogen dioxide, and sulphur dioxide can produce long-term harmful effects. They produce a risk of acute and long-term respiratory problems, and increased risk of cardiovascular disease and possibly cancer. Therefore, it is recommended that young children, the elderly, pregnant women, and those with anaemia, vascular, and respiratory problems should avoid exposure to unvented fuel burning heaters of any kind.

In certain kinds of housing, residents run a greater risk of asphyxiation. Very tight, but poorly insulated, buildings in cold climates have a high heat demand but low natural ventilation. Residents of poorly insulated apartments or trailers may have already caulked and weather-stripped. Unless ventilation is provided, the build-up of pollutants and carbon monoxide can prove life-threatening.

Moisture

In addition to the effects on the health of the occupants, unvented fuel-burning heaters can damage the structure of the building. When one gallon of kerosene is burned, slightly more than one gallon of water in vapor form is released into the air. Water vapor can pass through the inside surfaces of walls and ceilings into the stud spaces and the attic.

When the water vapor comes in contact with a cool surface, it condenses, wetting the insulation and the wood. Even in rooms where vapor barriers have been installed, the band joist area between the first and second floors is vulnerable. Damage to window frames and sills from moisture condensing on the glass can be extensive

Condensation in the attics of houses built with roof trusses can corrode steel truss plates. Excessive moisture is one of the most serious problems resulting from the use of unvented fuel burning heaters.

Safety

These safety precautions must be followed if the heater you are using burns kerosene. Heaters with built-in tanks must be allowed to cool and carried outdoors for refilling. Heaters with removable tanks can remain indoors while the tank is taken outside for refilling. Outdoor refilling is a must, since a small spill onto a warm heater might ignite the kerosene. Similarly, a spill indoors on a carpet might ignite when the heater is relit. Any drops of fuel spilled on the tank or heater must be wiped up before relighting.

Kerosene storage is also a problem. It should never be stored in the house, basement, or attached garage. It must be stored in a tight metal can clearly labelled “kerosene”, which has never been used to store any other fuel. Kerosene vapors are dangerous because they are heavier than air and will flow along the floor for a considerable distance, where they can be ignited by the heater or a pilot light on some other appliance.

Only the purest grade of kerosene, 1-K, should be used in heaters. Fuel oil and diesel fuel contain impurities, which will increase the odor problem, add air pollutants, and increase maintenance on the heater.

For portable kerosene heaters, the following safety precautions should be strictly observed:

• Use a heater listed by Underwriters’ Laboratories.
• Read all of the instructions with the heater.
• Always refuel the heater outdoors.
• Let the heater cool before refilling.
• Wipe up spills before relighting.
• Keep heaters away from drapes, curtains, furniture, clothing, children, newspapers, and pets.
• Do not carry the heater when it is lit.
• Keep a Class B fire extinguisher (for oil fires) near the heater. Have it close by when refuelling the heater.
• Do not use the heater where gases or vapors from aerosol cans are present. Many times the propellant is propane. The can may ignite and act as a flame-thrower.
• Store fuel in a tight metal container marked “kerosene”. Never put any other kind of fuel in the container.
• Store kerosene in a detached structure, away from the house.
• Watch for signs of excess moisture on windows and doors. Provide some amount of ventilation to overcome high relative humidity. Follow these precautions when using any fuel-burning heater.
• Never leave a child in charge of a fuel-burning heater.
• Never go to sleep with the heater on.
• Always provide sufficient ventilation.

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