A friend asked me what I thought of the infared heaters that are available for a source of zoned heat in residential homes. I understand that they heat by infared radiation(IR) and that around 49% of the Earth's warmth is IR from the sun, but I wasn't sure about it. I realize that smallest of light transmission is a form of radiation but these "untested, unknown"appliances are transmitting radiation around my family and I and I'm not sure about it. I can see the benefits of IR heating over conventional thermal air heating, especially in large areas such as warehouses where they have been employed for years, but I just still don't know. How much is too much? What brought it up is that Sam's Club has a brand that promises heat for up to 1,000 sq feet for $139.00. Any thoughts?