A new furnace was installed in the Alfieri home Saturday after a leak in their old furnace sent the whole family to the hospital with carbon monoxide poisoning.

Thirteen people in Omaha found themselves in the hospital as the result of two incidents of carbon monoxide poisoning.

"I started to feel light-headed and tingly," said Chris Alfieri. "I just didn't feel right."

But Alfieri says he had no idea at the time what was causing him to feel sick.

"It never occurred to us that it was carbon monoxide because we had always done everything we were supposed to," he said. "We had it checked out every year."

The residents of an apartment complex along south 30th Street also had no idea carbon monoxide was making them sick.

Eight people were sent to the hospital in that incident around 10 o'clock Friday night.

Investigators believe a faulty gas stove used to heat the home leaked the poisonous gas.

But in most cases carbon monoxide poisoning is a result of a broken furnace.

"Accidents do happen," said Stafford Flowers of Thermal Services. "Pipes get pulled out, birds fly into a chimney, so every case of carbon monoxide poisoning is literally preventable. And nine times out of ten a basic inspection will find that."

Flowers says the best prevention is to annually have a professional inspect your furnace.

"Probably out of every 100 to 500 furnaces, we see only one or two that have problems," he said.

But he says it's worth the trouble, because some cases of carbon monoxide in the home could prove deadly.

"What can I say," said Alfieri. "We are happy to be here."

Experts say a carbon monoxide level above 35 parts-per-million is considered dangerous.

The apartment complex on south 30th Street had a reading of 109 parts-per-million, while the Alfieri's home registered at 450 parts-per-million.

Having a detector is recommended but is not a substitute for having your furnace inspected.

Experts say there are too many things that can go wrong with a detector to solely rely on it.