Invisible Peril

By: Laurence Roy Stains, This Old House magazine (Page 1 of 4)

Photo: Jason Schmidt

Only steps from the two doors to their garage, the Gubbels family sits down for breakfast. Calm moments are rare in a household juggling the demands of a 2-year-old and Jim's job as a park ranger, but soon they will be even more scarce: Kristi became pregnant days after the family freed itself from the poison coming in from the garage.

Photo: Jason Schmidt

Thin wisps of theatrical smoke show a leak as it trails from an electrical outlet.

Photo: Jason Schmidt

About 15 minutes after Klossner and Greiner fill the Gubbel's garage with theatrical smoke, it streams under the weather-stripped door to the house and billows down the stairway to the basement.

Photo: Jason Schmidt

The vents are connected to ducts with a variable-speed fan that sends garage air out through a roof vent.

Browse Images

How-To Video

Browse More

How to Choose a Carbon Monoxide Detector

In this how-to video, This Old House plumbing and heating expert Richard Trethewey examines various types of carbon-monoxide detectors

Watch The Video

On Newsstands Now

In the Magazine

Easy Upgrades That Say Welcome Home

What You'll Learn:

The nightmare began on an ordinary November night in an ordinary house in central Iowa. Jim and Kristi Gubbels were in the basement of their 1960s ranch when, seemingly out of the blue, their new carbon monoxide detector went off. Both felt fine, so they simply reset the detector. After it sounded again, Jim called a heating contractor.

The contractor spent a couple hours testing the furnace and water heater but couldn't find the source of the gas. Then, as he was packing his tools, his detector showed carbon monoxide levels above 70 parts per million in the house. That's eight times the allowable federal level for outdoor air. Most firefighters responding to a carbon monoxide call would enter with gas masks if they detected that amount at the front door.

"Jim," the contractor said, "you guys shouldn't stay in the house tonight." By then Kristi's lips were tingling, and Jim's eyes burned. They worried that their 2-year-old, Nick, was in trouble too. So they woke him around midnight and headed to the hospital, where tests revealed all three had slightly elevated carbon monoxide levels in their blood. They were given pure oxygen to breathe.

All the next week, while the family camped out with Kristi's parents, Jim racked his brain trying to figure out the source of the carbon monoxide. After reading his water-heater manual, he thought he had solved the mystery: He added more rise to the vent. The family moved back home, and Jim bought a better detector that gives instantaneous readouts. Everything seemed fine — until Kristi, who runs a desktop publishing business out of an office in the basement, noticed levels on the detector had climbed past 20 ppm. "I was absolutely frustrated," Jim recalls. "I was thoroughly mad."

In the weeks that followed, the local gas company visited three times but found nothing. Another heating contractor said the eight-year-old furnace had a cracked heat exchanger (it didn't) and advised Jim to buy a new furnace. Meanwhile, the new detector went up one day to 77 ppm.

Shortly after New Year's, a friend suggested Kristi call Tom Greiner at the Iowa State Extension Service. Greiner has a Ph.D. in engineering; he also has a reputation for relentless investigation of carbon monoxide problems. After half a dozen visits to the Gubbels' home, Greiner made a startling discovery: The carbon monoxide in the house was coming from the garage.