Space heaters or portable heaters--no matter what they are called--must be used correctly to avoid personal injury. Anyone using these heating devices should know about their wide range of safety problems. From the Cooperative Extension, Institute of Agriculture and Natural Resources, University of Nebraska, Lincoln, here are some tips about using kerosene heaters in the home.
| Introduction |
Safety 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 fuel and money on the heating system built into their home. They should, however, use a 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, the number of people hospitalized because of kerosene heater accidents increased four times over the previous year.
According to the National Fire Protection Association (NFPA), most of the 2,400 injuries involved children who drank the kerosene or inhaled the fumes. Keep in mind that youngsters may be more vulnerable than adults to problems inherent with un-vented heaters since they are usually kept in the house during cold 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 children than adults. Caution is required with elderly persons for the same reasons.
Another hazard is the reduction in air quality. One form is the lowering of the amount of oxygen in the air. Gases from kerosene, fuel oil or natural gas, if not properly vented, can cause headaches and irritate chronic respiratory ailments. Carbon monoxide is more readily attached to the hemoglobin of the blood than oxygen. Hence, carbon monoxide reduces the blood's ability to transport life-giving oxygen to the body's cells. A person who inhales carbon monoxide will not likely recover immediately when moved to good air. It may still be a long time (frequently 24 to 48 hours) before the carbon monoxide is completely removed from the blood.
There is also the threat of burns. Kerosene heaters have an open flame. A fire can occur if fuel is spilled. Also, flammable vapors of many types from many sources can occur within a home or building. Few people realize the vapors from tile cement can be very explosive. It is not inconceivable for someone to use a space heater where tile cement is being put down or lacquers are being applied. Other sources include cleaning agents, adhesives, and some aerosol products. Any product using a solvent other than water is a potential source of fire or an explosion. There are other fire hazards, such as curtains, paper, carpets or anything in the home that is combustible.
Carbon monoxide poisoning deserves the most attention. Carbon monoxide is referred to as the silent killer. People overcome by carbon monoxide usually have no warning. Some may notice a slight tightness in the chest, but this may not be a major factor since the brain is being dulled by the absence of oxygen-rich blood and the warning is easily ignored or misunderstood.
The typical signs and reactions of acute carbon monoxide poisoning are headache, dizziness, drowsiness, nausea, vomiting, collapse, coma and death. Initially, the victim is pale; later the skin and mucous membranes become a cherry red color (this is most noticeable on light-skinned people). Loss of consciousness occurs at about 50 percent carboxyhemoglobin level. The precise moment depends on the duration of the exposure, ambient temperature, and the health and metabolism of the individual.
Recovery is usually without permanent damage unless tissue hypoxia was severe enough to result in brain degeneration. Use of barbiturates and alcohol increases susceptibility and the possibility of harm.
| Potential Problems |
Typical kerosene space heaters.
(Source: Michigan State University Cooperative Extension Service)
Some kerosene heater manufacturers claim 100 percent fuel combustion efficiency. This is inaccurate. Chemically, 94 percent combustion is the best that can be obtained. From the standpoint of all the heat released by the combustion process staying in a room, this "100 percent efficiency" could be true since gases are not vented to the outside. However, as the space heater operates, oxygen in the room is used, causing the combustion efficiency to become even less. As the combustion efficiency decreases, the contamination of the atmosphere increases.
The chemical reaction of the combustion process produces water vapor. For kerosene, the water vapor produced is just over one gallon of water (if condensation occurs) per gallon of kerosene burned. The heat energy contained in the water vapor is not recoverable unless the water condenses. Thus, water vapor buildup in the enclosed home can create problems with condensation, molds and mildew. And, if the relative humidity rises above 50 percent, the air temperature required to achieve equal comfort also will increase, requiring the use of more fuel.
Weatherization of modern homes presents a ventilation problem that homes in the first half of the century did not have. In those homes, it was not uncommon to see a curtain moving on a windy day. This meant that air in the home was being replaced by outside air.
In the newer homes, especially electric, underground and "super insulated" homes, construction and tightness limit air infiltration. Further, in electrically heated homes there is no chimney to exhaust air. In these types of homes, windows must be opened a little for ventilation or a ventilation system must be built in during construction. The "rule of thumb" for ventilation is 1 square inch of air inlet for each 1,000 Btu per hour of heater output. This may not seem like a lot, but engineers have calculated 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 quality problem in homes with a gas-fired range, refrigerator, dryer, water heater or furnace. Gases such as nitrogen dioxide, carbon monoxide, carbon dioxide and sulfur dioxide can accumulate at increased rates.
| Fuel Quality |
Fuel quality is a major problem with the kerosene heater. Pure or "water clear," "water white" or "lighting grade" kerosene is recommended 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 complex fuel classified as a light to middle distillate. Although jet fuel, diesel fuel and Number 1 fuel oil are similar to pure kerosene, they are not as pure and are not appropriate for use in kerosene heaters as a way to save kerosene or money.
Some people buy reasonably good fuel, but store it in contaminated containers. Contaminants from an impure product can cause the wick to gum or soot up with deposits. This can cause smoking and incomplete or improper combustion.
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 any type of gasoline!
| Energy Content and Cost |
The energy content of kerosene typically ranges between 120,000 and 130,000 Btu per gallon. This is slightly less than fuel oil, which has approximately 140,000 Btu per gallon.
Compare fuels on the basis of cost per unit of usable heat. For example, if we assume 94 percent combustion efficiency and an average heat energy content of 125,000 Btu per gallon, each gallon of kerosene provides 0.94 x 125,000 or 117,500 Btu of "usable" heat energy--assuming all the water vapor condenses to release the latent heat. (Note: If the water vapor does not condense, 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 energy tied up in water vapor) heat are shown in Table I.
| Table I. Units of fuels per 100,000 Btu | ||
| Fuel | Unit | Units per 100,000 |
| 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 usable heat would cost 1.40 x $0.60 = $0.84. The maximum price we could pay for other fuels and still have the same out-of-pocket costs for fuel are given in Table II.
| Table II. Price comparison of fuels | ||
| Fuel | Unit | 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 to continue looking for ways to cut their fuel bills.
Consider the electric space heater. The cost of electricity is coming in line with the other fuels. If projections hold, the electric space heater may be more cost-effective. And, electricity does not rob the oxygen from the home interior like fossil fuels do when they burn.
There is also a move by the LP Gas industry to introduce the cabinet heater into the United States market. At present, there are a few items in the NFPA codes that hamper their use. The LP Gas units will likely be on the market in the near future, however.
If you plan to buy a kerosene heater, set up a checklist to go by. Can you and your family live by the safety requirements it takes to own and safely operate one? In all cases, be sure to budget a good ion exchange or photo electric cell smoke detector in your plans.
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