MARION, Iowa — When thousands of Iowa homes flooded this year, thousands of Iowans lost the central heating system in their homes. Heating systems covered by floodwaters are no longer safe to use, says Iowa State University Housing Engineer Tom Greiner.
“A flooded heating system that works now can fail later. Flooded heating systems are a danger to the health and safety of the occupants and need to be replaced,” he said.
Until their central heating systems are replaced, some Iowans may be tempted to use unconventional means to heat their homes, Greiner said, “but this is clearly a case where it’s best to avoid the temptation.”
For example, burning charcoal and wood ALWAYS produces high, and potentially lethal, concentrations of carbon monoxide, he said. “It is dangerous to cook or heat indoors using a charcoal grill and must never be done, even for a short time.”
Likewise, it is dangerous to open the door on a gas oven to heat a home, Greiner continued. Gas ovens are not designed to operate with the door open or to heat the house. Opening the door changes the airflow across the gas burner and can increase emissions from the oven.
“Heating your home with a gas oven constitutes serious fire and air quality risks. Never heat your home with a gas oven, even for short periods,” he said.
Unvented supplemental space heaters — also known as vent-free heaters — are safer than charcoal grills or gas ovens, but Greiner warns that unvented portable heaters burning fossil fuels such as natural gas, LP gas (propane), fuel oil or kerosene pose health and safety risks.
Carbon Monoxide, Other Dangers with Unvented Heaters
“An unvented heater burning fossil fuel can be a health and safety risk. Without a chimney or vent, these heaters release the products of combustion into the area being heated — carbon dioxide, carbon monoxide, water vapor, nitrogen oxides and a host of other pollutants. These pollutants can adversely affect people’s health, especially the elderly, infants, children, pregnant women, those with pre-existing health problems or those who are ill,” Greiner explained.
The amount of carbon monoxide, a deadly toxin, produced by an unvented heater can vary widely. Carbon monoxide is produced during incomplete combustion. Anything that causes incomplete combustion, such as a shortage of combustion air to the heater, can increase the amounts of carbon monoxide produced. Low-level exposures to carbon monoxide cause symptoms much like those of the flu, including headaches, vomiting and lethargy. Higher exposures can cause convulsions and death, Greiner said.
If using an unvented heater for temporary heat:
- Make sure you read and understand the manufacturer’s instructions.
- Follow the instructions completely to reduce the risks.
- Open some windows to supply adequate combustion air.
- Don’t use these heaters while people are sleeping.
Unvented supplemental heaters are designed to supplement, not replace, the main heating source, the ISU Extension housing engineer noted. Using them as the main heating source can cause higher levels of pollutants to accumulate in a home than the manufacturers anticipated. The higher pollutant levels and longer period of operation increase health risks.
“Providing adequate outside air to improve combustion and dilute pollutants reduces the efficiency of these unvented heaters. Plus, since these heaters should not be used when people are sleeping, makes them even less useful as a heating source,” Greiner said.
Fire Safety Concerns
Fire safety of unvented heaters also is a consideration, Greiner continued. He offered the following suggestions for reducing the risk of fire.
- Follow the manufacturers’ instructions for how to refuel the heater. This usually requires that the heater be cool before refueling and that the refueling be performed outdoors.
- Maintain proper clearances around unvented heaters to prevent burns and reduce the fire risks.
- Don’t allow children and pets to come in contact with the heater.
- All homes should have fire extinguishers, smoke alarms and carbon monoxide detectors. Check extinguishers, alarms and detectors periodically to ensure they are working correctly. Replace batteries as needed. If an alarm sounds, take it seriously.
Potential for Mold, Wood Decay
Excess water in Iowa homes increases the potential for mold and wood decay, Greiner said.
“Water vapor will be produced during combustion of fossil fuels in an unvented heater. Many fossil fuels including LP gas, kerosene and natural gas, produce more than a gallon of water vapor for every gallon of fuel burned,” he noted.
In homes that were flooded, drying the house is vitally important to reducing the risk of mold, he said. The moisture from an unvented heater can slow or stop the drying. Continuous operation of an unvented heater in a tight house with insufficient window openings will increase the moisture that builds up inside the house.
Greiner has seen serious mold problems and drywall failure after people operated an unvented heater indoors in the mistaken belief that the unvented heater would dry the home.
“In one home the drywall in the living room had sagged and was covered with mold after an unvented kerosene heater was operated continuously for a week. The occupants kept the living room doors and windows shut, and as the room become wetter and wetter they continued to operate the heater in a futile attempt to dry the room. It was difficult for them to realize that what seemed to them to be a hot, dry heat was actually a hot, wet heat,” he said.
Central Heating Is Best Option
The safest and for most people the most satisfactory method to heat their home, even temporarily, is with a central heating system properly installed by a qualified heating contractor.
“For help in selecting a home heating system, contact a qualified heating contractor, your utility company, officials handling local flood recovery efforts and building code officials,” Greiner suggested.
Special funding programs may be available for flood-affected homes to assist with the purchase and installation of a new, high-efficiency heating system. Consumers should contact their utility company for availability.
“These new heating systems increase efficiency, decrease heating costs, increase safety and improve the air quality in your home,” Greiner said.
“Rebuilding after a flood is tough, with so many decisions to make,” he said. “Spending the time to select and install a high-efficiency heating system — either gas, oil, electric or solar — will be time well spent, saving money on heating bills, increasing safety and improving the indoor air quality in your home.”
Laura Sternweis, Extension Communications and External Relations, (515) 294-0775,