Kerosene heaters

The Old House Web

Parts of this story: Introduction ~~ Potential problems ~~ Fuelquality ~~ Energy content and cost ~~ Shoppingchecklist ~~ Safetychecklist


Space heaters or portableheaters--no matter what they are called--must be used correctly to avoidpersonal injury. Anyone using these heating devices should know about their widerange of safety problems. Fromthe Cooperative Extension, Institute of Agriculture and Natural Resources,University of Nebraska, Lincoln, here are some tips about usingkerosene heaters in the home.


kerosene heaterSafety is not a primary concern for many people who buy kerosene heaters.They are looking at the perceived and claimed economics as a way to save fueland money on the heating system built into their home. They should, however, usea safety checklist before making an investment.

One major safety question is: How dangerous are kerosene heaters in a home?Shortly after the modern, portable, kerosene heater was introduced in 1979, thenumber of people hospitalized because of kerosene heater accidents increasedfour times over the previous year.

According to the National Fire Protection Association (NFPA), most of the2,400 injuries involved children who drank the kerosene or inhaled the fumes.Keep in mind that youngsters may be more vulnerable than adults to problemsinherent with un-vented heaters since they are usually kept in the house duringcold weather, whereas adults have an opportunity to get out into the open air.Also, the tolerance level for air-borne contaminants often is lower for childrenthan adults. Caution is required with elderly persons for the same reasons.

Another hazard is the reduction in air quality. One form is thelowering of the amount of oxygen in the air. Gases from kerosene, fuel oil ornatural gas, if not properly vented, can cause headaches and irritate chronicrespiratory ailments. Carbon monoxide is more readily attached to the hemoglobinof the blood than oxygen. Hence, carbon monoxide reduces the blood's ability totransport life-giving oxygen to the body's cells. A person who inhales carbonmonoxide will not likely recover immediately when moved to good air. It maystill be a long time (frequently 24 to 48 hours) before the carbon monoxide iscompletely removed from the blood.

There is also the threat of burns. Kerosene heaters have an open flame. Afire can occur if fuel is spilled. Also, flammable vapors of many types frommany sources can occur within a home or building. Few people realize thevapors from tile cement can be very explosive. It is not inconceivable forsomeone to use a space heater where tile cement is being put down or lacquersare being applied. Other sources include cleaning agents, adhesives, andsome aerosol products. Any product using a solvent other than water is apotential source of fire or an explosion. There are other fire hazards, such ascurtains, paper, carpets or anything in the home that is combustible.

Carbon monoxide poisoning deserves the most attention. Carbon monoxide isreferred to as the silent killer. People overcome by carbon monoxide usuallyhave no warning. Some may notice a slight tightness in the chest, but this maynot be a major factor since the brain is being dulled by the absence ofoxygen-rich blood and the warning is easily ignored or misunderstood.

The typical signs and reactions of acute carbon monoxide poisoning areheadache, dizziness, drowsiness, nausea, vomiting, collapse, coma and death.Initially, the victim is pale; later the skin and mucous membranes become acherry red color (this is most noticeable on light-skinned people). Loss ofconsciousness occurs at about 50 percent carboxyhemoglobin level. The precisemoment depends on the duration of the exposure, ambient temperature, and thehealth and metabolism of the individual.

Recovery is usually without permanent damage unless tissue hypoxia was severeenough to result in brain degeneration. Use of barbiturates and alcoholincreases susceptibility and the possibility of harm.

Potential Problems

space heaters
Typical kerosene space heaters.
(Source: MichiganState University Cooperative Extension Service)

Some kerosene heater manufacturers claim 100 percent fuel combustionefficiency. This is inaccurate. Chemically, 94 percent combustion is the bestthat can be obtained. From the standpoint of all the heat released by thecombustion process staying in a room, this "100 percent efficiency"could be true since gases are not vented to the outside. However, as the spaceheater operates, oxygen in the room is used, causing the combustion efficiencyto become even less. As the combustion efficiency decreases, the contaminationof the atmosphere increases.

The chemical reaction of the combustion process produces water vapor. Forkerosene, the water vapor produced is just over one gallon of water (ifcondensation occurs) per gallon of kerosene burned. The heat energy contained inthe water vapor is not recoverable unless the water condenses. Thus, water vaporbuildup in the enclosed home can create problems with condensation, molds andmildew. And, if the relative humidity rises above 50 percent, the airtemperature required to achieve equal comfort also will increase, requiring theuse of more fuel.

Weatherization of modern homes presents a ventilation problem that homes inthe first half of the century did not have. In those homes, it was not uncommonto see a curtain moving on a windy day. This meant that air in the home wasbeing replaced by outside air.

In the newer homes, especially electric, underground and "superinsulated" homes, construction and tightness limit air infiltration.Further, in electrically heated homes there is no chimney to exhaust air. Inthese types of homes, windows must be opened a little for ventilation or aventilation system must be built in during construction. The "rule ofthumb" for ventilation is 1 square inch of air inlet for each 1,000 Btu perhour of heater output. This may not seem like a lot, but engineers havecalculated that this size of opening can lose up to 12,000 Btu of heat per hour-- almost the same amount of heat provided by the heater.

There also is evidence that a space heater can compound an air qualityproblem in homes with a gas-fired range, refrigerator, dryer, water heater orfurnace. Gases such as nitrogen dioxide, carbon monoxide, carbon dioxide andsulfur dioxide can accumulate at increased rates.

Fuel Quality

Fuel quality is a major problem with the kerosene heater. Pure or "waterclear," "water white" or "lighting grade" kerosene isrecommended as the ultimate in fuel use. Many problems occur when diesel fuel,furnace fuel and even gasoline are used in the heaters. Kerosene is a complexfuel classified as a light to middle distillate. Although jet fuel, diesel fueland Number 1 fuel oil are similar to pure kerosene, they are not as pure and arenot appropriate for use in kerosene heaters as a way to save kerosene or money.

Some people buy reasonably good fuel, but store it in contaminatedcontainers. Contaminants from an impure product can cause the wick to gum orsoot up with deposits. This can cause smoking and incomplete or impropercombustion.

Shop around for a good source of high quality kerosene. Don't use furnace,diesel or jet fuel. On threat of death by explosion, never use anytype of gasoline!

Energy Content and Cost

The energy content of kerosene typically ranges between 120,000 and 130,000Btu per gallon. This is slightly less than fuel oil, which has approximately140,000 Btu per gallon.

Compare fuels on the basis of cost per unit of usable heat. For example, ifwe assume 94 percent combustion efficiency and an average heat energy content of125,000 Btu per gallon, each gallon of kerosene provides 0.94 x 125,000 or117,500 Btu of "usable" heat energy--assuming all the water vaporcondenses to release the latent heat. (Note: If the water vapor does notcondense, the usable heat is 9,500 Btu lower). Thus, 100,000 Btu of"usable" heat requires 100,000 - 117,500, or 0.85 gallon of kerosene.The amounts of other fuels needed to provide 100,000 Btu of usable (no energytied up in water vapor) heat are shown in Table I.

Table I. Units of fuels per 100,000 Btu



Units per 100,000
Btu of usable heat

Fuel Oil gallon 1.21
Propane gallon 1.57
Natural Gas 100s of cu. ft. 1.40
Electricity kWh 29.31

Using natural gas at 60 per 100 cu. ft. as a base, 100,000 Btu of usableheat would cost 1.40 x $0.60 = $0.84. The maximum price we could pay for otherfuels and still have the same out-of-pocket costs for fuel are given in TableII.


Table II. Price comparison of fuels



Maximum price per unit

Fuel Oil gallon $0.69
Propane gallon $0.54
Electricity KWh $0.029
Kerosene gallon $0.99

The Future

Our energy problem is not going to go away. Consequently, people are going tocontinue looking for ways to cut their fuel bills.

Consider the electric space heater. The cost of electricity is coming in linewith the other fuels. If projections hold, the electric space heater may be morecost-effective. And, electricity does not rob the oxygen from the home interiorlike fossil fuels do when they burn.

There is also a move by the LP Gas industry to introduce the cabinet heaterinto the United States market. At present, there are a few items in the NFPAcodes that hamper their use. The LP Gas units will likely be on the market inthe near future, however.

If you plan to buy a kerosene heater, set up a checklist to go by. Can youand your family live by the safety requirements it takes to own and safelyoperate one? In all cases, be sure to budget a good ion exchange or photoelectric cell smoke detector in your plans.

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