This is provided through energy specialists with K-State Research and Extension. Following are some questions dealing with energy use that will hopefully be useful. Unvented gas logs use indoor air for combustion and vent the combustion by-products directly into the room, said Bruce Snead, Extension specialist in residential energy at Kansas State University. Most building scientists do not recommend ventless heaters in homes where moisture problems exist, where small children and elderly persons live, or where the heater is likely to be operated for more than two hours per day. Under no circumstances should you install ventless heaters in airtight houses, mobile homes, or trailers, he said.
Occupant safety is a major concern.
Improperly installed or malfunctioning ventless heaters introduce combustion gases, large amounts of water vapor, and possibly consume much of the oxygen in a room. Depending upon the level of exposure, these pollutants and the lack of oxygen can cause eye irritation, headaches, dizziness, fatigue, respiratory problems, and possibly death, he said. Newer unvented heaters have sensors intended to automatically shut off the burner when the oxygen level in the room falls below a safe level. However, even these new UL-listed appliances dump large amounts of water vapor into a home and are not intended for prolonged use, Snead said. Check with your local fire and health officials to determine if unvented heaters are permitted in your area before you install one, he said.